Twin and triplet pregnancy

This guideline covers the care that should be offered to women with a twin or triplet pregnancy in addition to the routine care that is offered to all women during pregnancy. It aims to reduce the risk of complications and improve outcomes for women and their babies.

# Recommendations
People have the right to be involved in discussions and make informed decisions about their care, as described in NICE's information on making decisions about your care.
Making decisions using NICE guidance explains how we use words to show the strength (or certainty) of our recommendations, and has information about prescribing medicines (including off-label use), professional guidelines, standards and laws (including on consent and mental capacity), and safeguarding.
Type of pregnancy
Chorionicity and amnionicity
Dichorionic diamniotic twins
Both babies have a separate placenta and amniotic sac.
Monochorionic diamniotic twins
Both babies share a placenta but have separate amniotic sacs.
Monochorionic monoamniotic twins
Both babies share a placenta and amniotic sac.
Trichorionic triamniotic triplets
Each baby has a separate placenta and amniotic sac.
Dichorionic triamniotic triplets
One baby has a separate placenta and 2 of the babies share a placenta.
All 3 babies have separate amniotic sacs.
Dichorionic diamniotic triplets
One baby has a separate placenta and amniotic.
Two of the babies share a placenta and amniotic sac.
Monochorionic triamniotic triplets
All 3 babies share 1 placenta.
All 3 babies have separate amniotic sacs.
Monochorionic diamniotic triplets
All 3 babies share 1 placenta.
One baby has a separate amniotic sac and 2 babies share 1 sac.
Monochorionic monoamniotic triplets
All 3 babies share a placenta and amniotic sac.

# Determining gestational age and chorionicity

## Gestational age
Offer women with a twin or triplet pregnancy a first trimester ultrasound scan to estimate gestational age and determine chorionicity and amnionicity (ideally, these should all be performed at the same scan; see the recommendations on determining chorionicity and amnionicity and assigning nomenclature). See the recommendations on screening for chromosomal conditions. 
Estimate gestational age from the largest baby in a twin or triplet pregnancy to avoid the risk of estimating it from a baby with early growth pathology. 

## Chorionicity and amnionicity
Determine chorionicity and amnionicity at the time of detecting a twin or triplet pregnancy by ultrasound using:
the number of placental masses
the presence of amniotic membrane(s) and membrane thickness
the lambda or Tsign. 
Assign nomenclature to babies (for example, upper and lower, or left and right) in a twin or triplet pregnancy, and document this clearly in the woman's notes to ensure consistency throughout pregnancy. 
If a woman with a twin or triplet pregnancy presents after 14+0 weeks, determine chorionicity and amnionicity at the earliest opportunity by ultrasound using all of the following:
the number of placental masses
the presence of amniotic membrane(s) and membrane thickness
the lambda or T-sign
discordant fetal sex. 
If it is not possible to determine chorionicity or amnionicity by ultrasound at the time of detecting the twin or triplet pregnancy, seek a second opinion from a senior sonographer or refer the woman to a healthcare professional who is competent in determining chorionicity and amnionicity by ultrasound scan as soon as possible. 
If it is difficult to determine chorionicity, even after referral (for example, because the woman has booked late in pregnancy), manage the pregnancy as a monochorionic pregnancy until proved otherwise. 
Provide regular training so that sonographers can identify the lambda or T-sign accurately and confidently. Less experienced sonographers should have support from senior colleagues. 
Training should cover ultrasound scan measurements needed for women who book after 14+0 weeks and should emphasise that the risks associated with twin and triplet pregnancy are determined by chorionicity and not zygosity. 
Conduct regular clinical audits to evaluate the accuracy of determining chorionicity and amnionicity. 
If transabdominal ultrasound scan views are poor because of a retroverted uterus or a high BMI, use a transvaginal ultrasound scan to determine chorionicity and amnionicity. 
Do not use 3dimensional (3D) ultrasound scans to determine chorionicity and amnionicity. 
Networks should agree care pathways for managing all twin and triplet pregnancies to ensure that each woman has a care plan in place that is appropriate for the chorionicity and amnionicity of her pregnancy. 

# General care

## Information and emotional support
Explain sensitively the aims and possible outcomes of all screening and diagnostic tests to women with a twin or triplet pregnancy to minimise their anxiety. 

## Diet, lifestyle and nutritional supplements
Give women with a twin or triplet pregnancy the same advice about diet, lifestyle and nutritional supplements as in routine antenatal care (see NICE's guideline on antenatal care for uncomplicated pregnancies). 
Be aware of the higher incidence of anaemia in women with a twin or triplet pregnancy compared with women with a singleton pregnancy. 
Perform a full blood count at 20 to 24 weeks to identify women with a twin or triplet pregnancy who need early supplementation with iron or folic acid (this is in addition to the test for anaemia at the routine booking appointment recommended in NICE's guideline on antenatal care for uncomplicated pregnancies). Repeat at 28 weeks as in routine antenatal care. 

# Delivery of antenatal and intrapartum care

## Antenatal care
Antenatal clinical care for women with a twin or triplet pregnancy should be provided by a nominated multidisciplinary team consisting of:
a core team of named specialist obstetricians, specialist midwives and sonographers, all of whom have experience and knowledge of managing twin and triplet pregnancies
an enhanced team for referrals, which should include:
a perinatal mental health professional
a women's health physiotherapist
an infant feeding specialist
a dietitian. 
Members of the enhanced team should have experience and knowledge relevant to twin and triplet pregnancies. 
Do not routinely refer all women with a twin or triplet pregnancy to the enhanced team but base the decision to refer on each woman's needs. 
Coordinate clinical care for women with a twin or triplet pregnancy to:
minimise the number of hospital visits
provide care as close to the woman's home as possible
provide continuity of care within and between hospitals and the community. 
The core team should offer information and emotional support specific to twin and triplet pregnancies at their first contact with the woman and provide ongoing opportunities for further discussion and advice including:
antenatal and postnatal mental health and wellbeing
antenatal nutrition (see the recommendation on giving advice in the section on diet, lifestyle and nutritional supplements)
the risks, symptoms and signs of preterm labour and the potential need for corticosteroids for fetal lung maturation
likely timing of birth (see the section on timing of birth) and possible modes of birth (see the section on mode of birth)
breastfeeding
parenting. 

## Intrapartum care
Intrapartum care for women with a twin or triplet pregnancy should be provided by a multidisciplinary team of obstetricians and midwives who have experience and knowledge of managing twin and triplet pregnancies in the intrapartum period. 
For a short explanation of why the committee made the 2019 recommendation and how it might affect practice, see the rationale and impact on intrapartum care .
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## Schedule of specialist antenatal appointments
The schedule of specialist appointments is also shown as part of a multiple pregnancy antenatal care resource produced by Twins Trust and endorsed by NICE.
Offer women with an uncomplicated dichorionic diamniotic twin pregnancy at least 8 antenatal appointments with a healthcare professional from the core team. At least 2 of these appointments should be with the specialist obstetrician.
Combine appointments with scans when crownrump length measures from 45.0 mm to 84.0 mm (at approximately 11+2 weeks to 14+1 weeks) and then at estimated gestations of 20, 24, 28, 32 and 36 weeks.
Offer additional appointments without scans at 16 and 34 weeks. 
Offer women with an uncomplicated monochorionic diamniotic twin pregnancy at least 11 antenatal appointments with a healthcare professional from the core team. At least 2 of these appointments should be with the specialist obstetrician.
Combine appointments with scans when crownrump length measures from 45.0 mm to 84.0 mm (at approximately 11+2 weeks to 14+1 weeks) and then at estimated gestations of 16, 18, 20, 22, 24, 26, 28, 30, 32 and 34 weeks. 
Offer women with an uncomplicated trichorionic triamniotic triplet pregnancy at least 9 antenatal appointments with a healthcare professional from the core team. At least 2 of these appointments should be with the specialist obstetrician.
Combine appointments with scans when crownrump length measures from 45.0 mm to 84.0 mm (at approximately 11+2 weeks to 14+1 weeks) and then at estimated gestations of 20, 24, 26, 28, 30, 32 and 34 weeks.
Offer an additional appointment without a scan at 16 weeks. 
Offer women with a dichorionic triamniotic or monochorionic triamniotic triplet pregnancy at least 11 antenatal appointments with a healthcare professional from the core team. At least 5 of these appointments should be with the specialist obstetrician.
Combine appointments with scans when crownrump length measures from 45.0 mm to 84.0 mm (at approximately 11+2 weeks to 14+1 weeks) and then at estimated gestations of 16, 18, 20, 22, 24, 26, 28, 30, 32 and 34 weeks. 
Offer women with a twin or triplet pregnancy involving a shared amnion individualised care from a consultant in a tertiary level fetal medicine centre (see the recommendation on indications for referral to a tertiary level fetal medicine centre). 

# Fetal complications

## Information about screening
A healthcare professional with experience of caring for women with twin and triplet pregnancies should offer information and counselling to women before and after every screening test. 
Inform women with a twin or triplet pregnancy about the complexity of decisions they may need to make depending on the outcomes of screening, including different options according to the chorionicity and amnionicity of the pregnancy. 

## Screening for chromosomal conditions
Offer women with a twin pregnancy information on and screening for Down's syndrome, Edwards' syndrome and Patau's syndrome as outlined in the NHS fetal anomaly screening programme (FASP). 
Before offering screening for Down's syndrome, Edwards' syndrome and Patau's syndrome, give women with a triplet pregnancy information about:
the greater likelihood of Down's syndrome, Edwards' syndrome and Patau's syndrome in triplet pregnancy
the different options for screening
the increased false positive rate of screening tests in triplet pregnancy
their greater likelihood of being offered invasive testing
their greater likelihood of complications of invasive testing
the physical risks and psychological implications in the short and long term relating to selective fetal reduction. 
Healthcare professionals who screen for Down's syndrome, Edwards' syndrome and Patau's syndrome in trichorionic triplet pregnancy should:
map the fetal positions
use nuchal translucency and maternal age to screen for Down's syndrome, Edwards' syndrome and Patau's syndrome when crownrump length measures from 45.0 mm to 84.0 mm (at approximately 11+2 weeks to 14+1 weeks)
calculate the chance of Down's syndrome, Edwards' syndrome and Patau's syndrome for each fetus. 
Refer women with a dichorionic and monochorionic triplet pregnancy who want to have screening for Down's syndrome, Edwards' syndrome and Patau's syndrome to a tertiary level fetal medicine centre. 
Do not use second trimester serum screening for Down's syndrome in triplet pregnancies. 
Refer women with any type of triplet pregnancy who have a higher chance of Down's syndrome, Edwards' syndrome or Patau's syndrome (use a threshold of 1 in 150 at term) to a fetal medicine specialist in a tertiary-level fetal medicine centre. 
For a short explanation of why the committee made the 2019 recommendations and how they might affect practice, see the rationale and impact section on screening for chromosomal conditions .
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## Screening for structural abnormalities
Offer screening for structural abnormalities (such as cardiac abnormalities) in twin and triplet pregnancies as in routine antenatal care; see NICE's guideline on antenatal care for uncomplicated pregnancies and the NHS fetal anomaly screening programme. 
Consider scheduling ultrasound scans in twin and triplet pregnancies at a slightly later gestational age than in singleton pregnancies and be aware that the scans will take longer to perform. 
Allow 45 minutes for the anomaly scan in twin and triplet pregnancies (as recommended by FASP). 
Allow 30 minutes for growth scans in twin and triplet pregnancies. 

## Screening for preterm birth
Also see the section on preventing preterm birth.
Explain to women and their family members or carers (as appropriate) that:
they have a higher risk of spontaneous preterm birth (see the section on timing of birth) than women with a singleton pregnancy and
this risk is further increased if they have other risk factors, such as a spontaneous preterm birth in a previous pregnancy. 
Do not use fetal fibronectin testing alone to predict the risk of spontaneous preterm birth in twin and triplet pregnancy. 
Do not use home uterine activity monitoring to predict the risk of spontaneous preterm birth in twin and triplet pregnancy. 
For a short explanation of why the committee made the 2019 recommendations (and why they did not make a recommendation on cervical length screening) and how they might affect practice, see the rationale and impact section on screening for preterm birth .
Full details of the evidence and the committee's discussion are in evidence review D: screening for spontaneous preterm birth.
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## Screening for fetal growth restriction and feto-fetal transfusion syndrome in the first trimester
Do not offer women with a twin or triplet pregnancy screening for fetal growth restriction or feto-fetal transfusion syndrome in the first trimester. 
For a short explanation of why the committee made this 2019 recommendation and how it might affect practice, see the rationale and impact section on screening for fetal growth restriction and feto-fetal transfusion syndrome in the first trimester .
Full details of the evidence and the committee's discussion are in evidence review A: screening for feto-fetal transfusion syndrome and evidence review B: screening for fetal growth restriction.
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## Diagnostic monitoring for fetal growth restriction in dichorionic twin and trichorionic triplet pregnancies
Do not use abdominal palpation or symphysisfundal height measurements to monitor for fetal growth restriction in a dichorionic twin or trichorionic triplet pregnancy. 
At each ultrasound scan from 24 weeks, offer women with a dichorionic twin or trichorionic triplet pregnancy diagnostic monitoring for fetal weight discordance using 2 or more biometric parameters and amniotic fluid levels. To assess amniotic fluid levels, measure the deepest vertical pocket (DVP) on either side of the amniotic membrane. 
Continue monitoring for fetal weight discordance at intervals that do not exceed:
days for women with a dichorionic twin pregnancy
days for women with a trichorionic triplet pregnancy. 
Calculate and document estimated fetal weight (EFW) discordance for dichorionic twins using the formula below : (  EFW larger fetus)  100
Calculate and document EFW discordance for trichorionic triplets using the formula below :(  EFW largest fetus)  100and(  EFW largest fetus)  100
Increase diagnostic monitoring in the second and third trimesters to at least weekly, and include doppler assessment of the umbilical artery flow for each baby, if:
there is an EFW discordance of 20% or more and/or
the EFW of any of the babies is below the 10th centile for gestational age. 
Refer women with a dichorionic twin or trichorionic triplet pregnancy to a tertiary level fetal medicine centre if there is an EFW discordance of 25% or more and the EFW of any of the babies is below the 10th centile for gestational age because this is a clinically important indicator of selective fetal growth restriction. 
For a short explanation of why the committee made the 2019 recommendations and how they might affect practice, see the rationale and impact section on diagnostic monitoring for fetal growth restriction in dichorionic twin and trichorionic triplet pregnancies .
Full details of the evidence and the committee's discussion are in evidence review B: screening for fetal growth restriction.
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## Diagnostic monitoring for complications of monochorionicity in twin and triplet pregnancy
A monochorionic twin or triplet pregnancy is one in which any of the babies share a placenta and a chorionic (outer) membrane. This includes monochorionic twins and dichorionic and monochorionic triplets.
Offer women simultaneous monitoring for feto-fetal transfusion syndrome, fetal growth restriction and advanced-stage twin anaemia polycythaemia sequence (TAPS) at every ultrasound assessment to monitor effectively for all complications of monochorionicity. Explain that the relative likelihood of each complication changes with advancing gestation but that they can all occur at any gestational age. 
Offer diagnostic monitoring for feto-fetal transfusion syndrome to women with a monochorionic twin or triplet pregnancy. Monitor with ultrasound every 14 days from 16 weeks until birth. 
Use ultrasound assessment, with a visible amniotic membrane within the measurement image, to monitor for feto-fetal transfusion syndrome. Measure the DVP depths of amniotic fluid on either side of the amniotic membrane. 
Increase the frequency of diagnostic monitoring for feto-fetal transfusion syndrome in the woman's second and third trimester to at least weekly if there are concerns about differences between the babies' amniotic fluid level (a difference in DVP depth of 4 cm or more). Include doppler assessment of the umbilical artery flow for each baby. 
Refer the woman to a tertiary level fetal medicine centre if feto-fetal transfusion syndrome is diagnosed, based on the following:
the amniotic sac of 1 baby has a DVP depth of less than 2 cm and
the amniotic sac of another baby has a DVP depth of:
-ver 8 cm before 20+0 weeks of pregnancy or
-ver 10 cm from 20+0 weeks. 
Refer the woman to her named specialist obstetrician for multiple pregnancy in her second or third trimester for further assessment and monitoring if:
the amniotic sac of 1 baby has a DVP depth in the normal range and
the amniotic sac of another baby has a DVP depth of:
less than 2 cm or
cm or more. 
For a short explanation of why the committee made the 2019 recommendations and how they might affect practice, see the rationale and impact section on diagnostic monitoring for feto-fetal transfusion syndrome .
Full details of the evidence and the committee's discussion are in evidence review A: screening for feto-fetal transfusion syndrome.
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Do not use abdominal palpation or symphysisfundal height measurements to monitor for fetal growth restriction in women with a monochorionic twin or triplet pregnancy. 
At each ultrasound scan from 16 weeks, offer women with a monochorionic twin or triplet pregnancy diagnostic monitoring for fetal weight discordance using 2 or more biometric parameters (in addition to amniotic fluid level assessment). To assess amniotic fluid levels, measure the DVP on either side of the amniotic membrane. 
Continue monitoring women with a monochorionic twin or triplet pregnancy for fetal weight discordance at intervals that should not exceed 14 days. 
Calculate and document EFW discordance in monochorionic twins using the formula below : (  EFW larger fetus)  100
The named specialist obstetrician should review the estimated fetal weights of dichorionic and monochorionic triplets and calculate EFW discordance based on their understanding of the implications of chorionicity. 
Increase diagnostic monitoring in the second and third trimesters to at least weekly, and include doppler assessment of the umbilical artery flow for each baby, if:
there is an EFW discordance of 20% or more and/or
the EFW of any of the babies is below the 10th centile for gestational age. 
Refer women with a monochorionic twin or triplet pregnancy to a tertiary level fetal medicine centre if there is an EFW discordance of 25% or more and the EFW of any of the babies is below the 10th centile for gestational age because this is a clinically important indicator of selective fetal growth restriction. 
For a short explanation of why the committee made the 2019 recommendations and how they might affect practice, see rationale and impact section on diagnostic monitoring for fetal growth restriction in monochorionic pregnancy .
Full details of the evidence and the committee's discussion are in evidence review B: screening for fetal growth restriction.
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Offer weekly ultrasound monitoring for TAPS from 16 weeks of pregnancy using middle cerebral artery peak systolic velocity (MCAPSV) to women whose pregnancies are complicated by:
feto-fetal transfusion syndrome that has been treated by fetoscopic laser therapy or
selective fetal growth restriction (defined by an EFW discordance of 25% or more and an EFW of any of the babies below the 10th centile for gestational age). 
For women with a monochorionic pregnancy showing any of the following:
cardiovascular compromise (such as fetal hydrops or cardiomegaly) or
unexplained isolated polyhydramnios or
abnormal umbilical artery perform ultrasound MCAPSV measurements to help detect advanced-stage TAPS, and seek management advice immediately from a tertiary level fetal medicine specialist. 
For a short explanation of why the committee made the 2019 recommendations and how they might affect practice, see the rationale and impact section on diagnostic monitoring for TAPS .
Full details of the evidence and the committee's discussion are in evidence review C: screening for TAPS.
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# Preventing preterm birth
The committee did not make any recommendations on vaginal progesterone for preventing preterm birth in twin pregnancies because of emerging evidence in this area. NICE will carry out an exceptional update based on the new evidence when it becomes available.
Do not offer intramuscular progesterone to prevent spontaneous preterm birth in women with a twin or triplet pregnancy. 
Do not offer the following interventions (alone or in combination) routinely to prevent spontaneous preterm birth in women with a twin or triplet pregnancy:
arabin pessary
bed rest
cervical cerclage
-ral tocolytics. 
For a short explanation of why the committee made the 2019 recommendations (and why they did not make a recommendation on vaginal progesterone) and how they might affect practice, see the rationale and impact section on preventing preterm birth .
Full details of the evidence and the committee's discussion are in evidence review E: interventions to prevent spontaneous preterm birth.
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## Corticosteroids
Inform women with a twin or triplet pregnancy of their increased risk of preterm birth (see the recommendation explaining screening for preterm birth to women and their family members in the section on screening for preterm birth) and about the benefits of targeted corticosteroids. 
Do not use single or multiple untargeted (routine) courses of corticosteroids in twin or triplet pregnancy. Inform women that there is no benefit in using untargeted administration of corticosteroids. 

# Maternal complications

## Hypertension
Measure blood pressure and test urine for proteinuria to screen for hypertensive disorders at each antenatal appointment in a twin and triplet pregnancy in line with NICE's guideline on antenatal care for uncomplicated pregnancies. 
Advise women with a twin or triplet pregnancy to take low-dose aspirin daily from 12 weeks until the birth of the babies if they have 2 or more of the risk factors specified in NICE's guideline on hypertension in pregnancy. In September 2019, this was an off-label use of aspirin. See NICE's information on prescribing medicines.

# Indications for referral to a tertiary level fetal medicine centre
Seek a consultant opinion from a tertiary level fetal medicine centre for:
pregnancies with a shared amnion:
monochorionic monoamniotic twins
dichorionic diamniotic triplets
monochorionic diamniotic triplets
monochorionic monoamniotic triplets
pregnancies complicated by any of the following:
fetal weight discordance (of 25% or more) and an EFW of any of the babies below the 10th centile for gestational age
fetal anomaly (structural or chromosomal)
discordant fetal death
feto-fetal transfusion syndrome
twin reverse arterial perfusion sequence (TRAP)
conjoined twins or triplets
suspected TAPS (see the recommendations in the section on twin anaemia polycythaemia sequence). 

# Planning birth: information and support
From 24 weeks in a twin or triplet pregnancy, discuss with the woman (and her family members or carers, as appropriate) her plans and wishes for the birth of her babies. Provide information that is tailored to each woman's pregnancy, taking into account her needs and preferences. Revisit these conversations whenever clinically indicated and whenever the woman wants to. 
Ensure the following has been discussed by 28 weeks at the latest:
place of birth and the possible need to transfer in case of preterm birth
timing and possible modes of birth
analgesia during labour (or for caesarean birth)
intrapartum fetal heart monitoring
management of the third stage of labour. 
Follow NICE's guideline on patient experience in adult NHS services for how to provide information and communicate with women and their families and carers. 
For a short explanation of why the committee made the 2019 recommendations and how they might affect practice, see the rationale and impact section on planning birth .
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# Timing of birth

## Antenatal information for women
Explain to women with a twin pregnancy that about 60 in 100 twin pregnancies result in spontaneous birth before 37 weeks. 
Explain to women with a triplet pregnancy that about 75 in 100 triplet pregnancies result in spontaneous birth before 35 weeks. 
Explain to women with a twin or triplet pregnancy that spontaneous preterm birth and planned preterm birth are associated with an increased risk of admission to a neonatal unit. 
Explain to women with an uncomplicated dichorionic diamniotic twin pregnancy that:
planned birth from 37+0 weeks does not appear to be associated with an increased risk of serious neonatal adverse outcomes and
continuing the pregnancy beyond 37+6 weeks increases the risk of fetal death. 
Explain to women with an uncomplicated monochorionic diamniotic twin pregnancy that:
planned birth from 36+0 weeks does not appear to be associated with an increased risk of serious neonatal adverse outcomes and
continuing the pregnancy beyond 36+6 weeks increases the risk of fetal death. 
Explain to women with an uncomplicated monochorionic monoamniotic twin pregnancy that planned birth between 32+0 and 33+6 weeks does not appear to be associated with an increased risk of serious neonatal adverse outcomes. Also explain that:
these babies will usually need to be admitted to the neonatal unit and have an increased risk of respiratory problems
continuing the pregnancy beyond 33+6 weeks increases the risk of fetal death. 
Explain to women with an uncomplicated trichorionic triamniotic or dichorionic triamniotic triplet pregnancy that continuing the pregnancy beyond 35+6 weeks increases the risk of fetal death. 
Explain to women with a monochorionic triamniotic triplet pregnancy or a triplet pregnancy that involves a shared amnion that the timing of birth will be decided and discussed with each woman individually. 

## When to offer planned birth
Offer planned birth at 37 weeks to women with an uncomplicated dichorionic diamniotic twin pregnancy. 
Offer planned birth as follows, after a course of antenatal corticosteroids has been considered (see the section on maternal corticosteroids in NICE's guideline on preterm labour and birth):
at 36 weeks for women with an uncomplicated monochorionic diamniotic twin pregnancy
between 32+0 and 33+6 weeks for women with an uncomplicated monochorionic monoamniotic twin pregnancy
at 35 weeks for women with an uncomplicated trichorionic triamniotic or dichorionic triamniotic triplet pregnancy. 
Offer an individual assessment to determine the timing of planned birth in women with any of the following:
a complicated twin or triplet pregnancy
a monochorionic triamniotic triplet pregnancy
a triplet pregnancy that involves a shared amnion. 
For women who decline planned birth at the timing recommended in recommendations 1.9.9 and 1.9.10, offer weekly appointments with the specialist obstetrician. At each appointment, offer an ultrasound scan and perform assessments of amniotic fluid level and doppler of the umbilical artery flow for each baby in addition to fortnightly fetal growth scans. 
For a short explanation of why the committee made the 2019 recommendations and how they might affect practice, see the rationale and impact section on timing of birth .
Full details of the evidence and the committee's discussion are in evidence review J: timing of birth.
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# Mode of birth

## Twin pregnancy: dichorionic diamniotic or monochorionic diamniotic
Explain to women with an uncomplicated twin pregnancy planning their mode of birth that planned vaginal birth and planned caesarean section are both safe choices for them and their babies if all of the following apply:
the pregnancy remains uncomplicated and has progressed beyond 32 weeks
there are no obstetric contraindications to labour
the first baby is in a cephalic (head-first) presentation
there is no significant size discordance between the twins. 
Explain to women with an uncomplicated twin pregnancy that for women giving birth after 32 weeks (see recommendation 1.10.1):
more than a third of women who plan a vaginal birth go on to have a caesarean section
almost all women who plan a caesarean section do have one, but a few women have a vaginal birth before caesarean section can be carried out
a small number of women who plan a vaginal birth will need an emergency caesarean section to deliver the second twin after vaginal birth of the first twin. 
Offer caesarean section to women if the first twin is not cephalic at the time of planned birth. 
Offer caesarean section to women in established preterm labour between 26 and 32 weeks if the first twin is not cephalic. 
Offer an individualised assessment of mode of birth to women in suspected, diagnosed or established preterm labour before 26 weeks. Take into account the risks of caesarean section (see NICE's guideline on preterm labour and birth) and the chance of survival of the babies. 

## Twin pregnancy: monochorionic monoamniotic
Offer a caesarean section to women with a monochorionic monoamniotic twin pregnancy:
at the time of planned birth (between 32+0 and 33+6 weeks) or
after any complication is diagnosed in her pregnancy requiring earlier delivery or
if she is in established preterm labour, and gestational age suggests there is a reasonable chance of survival of the babies (unless the first twin is close to vaginal birth and a senior obstetrician advises continuing to vaginal birth). 

## Triplet pregnancy
Offer a caesarean section to women with a triplet pregnancy:
at the time of planned birth (35 weeks) or
after any complication is diagnosed in her pregnancy requiring earlier delivery or
if she is in established preterm labour, and gestational age suggests there is a reasonable chance of survival of the babies. 
For a short explanation of why the committee made the 2019 recommendations and how they might affect practice, see the rationale and impact section on mode of birth .
Full details of the evidence and the committee's discussion are in evidence review F: mode of birth.
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# Fetal monitoring during labour in twin pregnancy

## Antenatal information for women
By 28 weeks of pregnancy, discuss continuous cardiotocography with women with a twin pregnancy and their family members or carers (as appropriate) and address any concerns. Explain that the recommendations on cardiotocography are based on evidence from women with a singleton pregnancy because there is a lack of evidence specific to twin pregnancy or preterm babies. 
Explain to the woman that continuous cardiotocography is used to monitor the babies' heartbeats and her labour contractions, and that:
it allows simultaneous monitoring of both babies
it might restrict her mobility
normal traces show the babies are coping well with labour; if traces are not normal, there will be less certainty about the babies' condition
it is normal to see changes to the fetal heart rate pattern during labour and this does not necessarily mean there is a problem
findings from the cardiotocograph are used to help make decisions during labour and birth, but these will also be based on her wishes, her condition and that of her babies. 

## Intrapartum monitoring
Offer continuous cardiotocography to women with a twin pregnancy who are in established labour and are more than 26 weeks pregnant. 
Perform a portable ultrasound scan when established labour starts, to confirm which twin is which, the presentation of each twin, and to locate the fetal hearts. 
Do not offer intermittent auscultation to women with a twin pregnancy who are in established labour and are more than 26 weeks pregnant. 
For women between 23+0 and 25+6 weeks of pregnancy who are in established labour, involve a senior obstetrician in discussions with the woman and her family members or carers about how to monitor the fetal heart rates. 
When carrying out cardiotocography:
use dual channel cardiotocography monitors to allow simultaneous monitoring of both fetal hearts
document on the cardiotocograph and in the clinical records which cardiotocography trace belongs to which baby
monitor the maternal pulse electronically and display it simultaneously on the same cardiotocography trace. 
Consider separating the fetal heart rates by 20 beats/minute if there is difficulty differentiating between them. 
Classify and interpret cardiotocography in line with the section on the use of cardiotocography for monitoring during labour in the NICE guideline on fetal monitoring in labour, taking into account that:
twin pregnancy should be considered a fetal clinical risk factor when classifying a cardiotocography trace as 'abnormal' versus 'non-reassuring'
fetal scalp stimulation should not be performed in twin pregnancy to gain reassurance after a cardiotocography trace that is categorised as 'pathological'. 

## Reviewing cardiotocography
Carry out systematic assessments of both cardiotocographs at least hourly, and more frequently if there are concerns. 
At each systematic assessment, document which cardiotocography trace belongs to which baby. 
Be aware of the possibility of monitoring the same baby twice. At each cardiotocography review, ensure that twin synchronicity is not occurring. 

## Management based on cardiotocography
For definitions of 'suspicious' and 'pathological' cardiotocograph traces, see the table on management based on interpretation of cardiotocograph traces in NICE's guideline on intrapartum care for healthy women and babies.
If abdominal monitoring is unsuccessful or there are concerns about synchronicity of the fetal hearts:
involve a senior obstetrician and senior midwife
apply a fetal scalp electrode to the first baby (only after 34 weeks and if there are no contraindications) while continuing abdominal monitoring of the second baby
perform a bedside ultrasound scan to confirm both fetal heart rates
if monitoring remains unsatisfactory, consider a caesarean section. 
If the cardiotocograph trace is categorised as 'suspicious' in the first baby during established labour:
involve the senior obstetrician and senior midwife
correct any reversible causes
apply a fetal scalp electrode to the first baby (only after 34 weeks and if there are no contraindications) while continuing abdominal monitoring of the second baby. 
If the cardiotocograph trace is categorised as 'pathological' in the first baby during established labour:
involve the senior obstetrician and senior midwife
discuss with the woman and her family members or carers the possible use of fetal blood sampling of the first baby from 34 weeks if the benefits are likely to outweigh the potential risks. 
When offering fetal blood sampling in twin pregnancy, discuss with the woman and her family members or carers that if a blood sample cannot be obtained then she is likely to need a caesarean section. 
If the results of fetal blood sampling are not available within 20 minutes or fetal blood sampling is contraindicated, offer an immediate caesarean section to women with a twin pregnancy. 
If the cardiotocograph trace is categorised as 'pathological' in the first baby during the second stage of labour:
involve the senior obstetrician and senior midwife
assess whether an assisted vaginal birth is an option
if vaginal birth is not an option or cannot be achieved within 20 minutes, offer an immediate caesarean section. 
If the cardiotocograph trace of the second baby is categorised as 'suspicious' or 'pathological' during established labour before the first baby is born:
involve the senior obstetrician and senior midwife
if vaginal birth of the second baby cannot be achieved within 20 minutes, discuss performing a caesarean section with the woman and her family members or carers. 
After the birth of the first baby:
continue to monitor the second baby using cardiotocography
if there is 'suspicious' or 'pathological' cardiotocography, and vaginal birth cannot be achieved within 20 minutes, discuss performing a caesarean section with the woman and her family members or carers. 
After the birth of both babies, consider double clamping the cord to allow umbilical cord blood gases to be sampled. Ensure that the samples are correctly labelled for each baby. 
For a short explanation of why the committee made the 2019 recommendations and how they might affect practice, see the rationale and impact section on fetal monitoring during labour .
Full details of the evidence and the committee's discussion are in evidence review G: fetal monitoring.
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# Analgesia
Discuss options for analgesia and anaesthesia with women (and their family members or carers, as appropriate), whether they are planning a vaginal birth or caesarean section. Ensure this discussion takes place by 28 weeks at the latest. 
Offer an epidural to women with a twin or triplet pregnancy who choose to have a vaginal birth. Explain that this is likely to:
improve the chance of success and optimal timing of assisted vaginal birth of all the babies
enable a quicker birth by emergency caesarean section if needed. 
Offer regional anaesthesia to women with a twin or triplet pregnancy who are having a caesarean section. 
For a short explanation of why the committee made the 2019 recommendations and how they might affect practice, see the rationale and impact section on analgesia .
Full details of the evidence and the committee's discussion are in evidence review H: analgesia.
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# Managing the third stage of labour

## Assessing risk
Start assessing the risk of postpartum haemorrhage in women with a twin or triplet pregnancy in the antenatal period and continue throughout labour and the third stage (see the section on risk factors for postpartum haemorrhage in NICE's guideline on intrapartum care for healthy women and babies). 
Offer each woman an individualised assessment of her risk of postpartum haemorrhage and explain that multiple pregnancy is a risk factor for increased blood loss at delivery. 

## Management
By 28 weeks of pregnancy, discuss options for managing the third stage of labour with women with a twin or triplet pregnancy. 
Do not offer physiological management of the third stage to women with a twin or triplet pregnancy. 
Offer women with a twin or triplet pregnancy active management of the third stage. Explain that it is associated with a lower risk of postpartum haemorrhage and/or blood transfusion. 
Consider active management of the third stage with additional uterotonics for women who have 1 or more risk factors (in addition to a twin or triplet pregnancy) for postpartum haemorrhage. 

## Blood transfusion
By 28 weeks of pregnancy, discuss with women with a twin or triplet pregnancy the potential need for blood transfusion, including the need for intravenous access. Document this discussion in the woman's notes. 
At the start of established labour in women with a twin or triplet pregnancy:
ensure that intravenous access is available so that prompt blood transfusion and intravenous fluids can be given if needed
take a maternal blood sample for a full blood count and group and save. 
Ensure that the appropriate blood transfusion is available for urgent administration. 
For a short explanation of why the committee made the 2019 recommendations and how they might affect practice, see the rationale and impact section on managing the third stage of labour .
Full details of the evidence and the committee's discussion are in evidence review I: interventions to prevent postpartum haemorrhage in the third stage of labour.
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# Terms used in this guideline

## Active management of the third stage
In a vaginal birth, active management consists of 10 IU of oxytocin by intramuscular injection immediately after the birth of the last baby and before the cord is clamped and cut. In a caesarean section, it consists of 5 IU of oxytocin by intravenous injection immediately after the birth of the last baby and before the cord is clamped and cut.

## Amnionicity
The number of amnions (inner membranes) that surround babies in a multiple pregnancy. Pregnancies with 1 amnion (so that all babies share an amniotic sac) are described as monoamniotic; pregnancies with 2 amnions are diamniotic; and pregnancies with 3 amnions are triamniotic. Also see the box on chorionicity and amnionicity in twin and triplet pregnancy.

## Chorionicity
The number of chorionic (outer) membranes that surround babies in a multiple pregnancy. If there is only 1 membrane, the pregnancy is described as monochorionic; if there are 2, the pregnancy is dichorionic; and if there are 3, the pregnancy is trichorionic. Monochorionic twin pregnancies and monochorionic or dichorionic triplet pregnancies carry higher risks because babies share a placenta. Also see the box on chorionicity and amnionicity in twin and triplet pregnancy.

## Feto-fetal transfusion syndrome
Feto-fetal transfusion syndrome (FFTS) occurs when blood moves from one baby to another. The baby that loses the blood is called the donor and the baby receiving the blood is called the recipient. Feto-fetal transfusion syndrome is a complication of monochorionic multiple pregnancies arising from shared placental circulation. It is also referred to as twin-to-twin transfusion syndrome in twin pregnancies.

## Group and save
This is a blood sampling process. It consists of a blood group and an antibody screen to determine the woman's blood group and whether she has atypical red cell antibodies in her blood. If atypical antibodies are present, the laboratory will do additional work to identify them. This will allow blood to be issued in an emergency very quickly.

## Specialist obstetrician
An obstetrician with a special interest, experience and knowledge of managing multiple pregnancy, and who works regularly with women with a multiple pregnancy.

## Tertiary level fetal medicine centre
A specialist regional (or supra-regional) fetal medicine centre that has a multidisciplinary team with the expertise and infrastructure to assess and manage complicated twin and triplet pregnancies. This includes providing complex fetal interventions or therapies, for example, fetoscopic laser ablation for feto-fetal transfusion syndrome; and selective termination of pregnancy using techniques such as fetoscopic cord occlusion or radiofrequency ablation.

## Twin anaemia polycythaemia sequences
Twin anaemia polycythaemia sequences (TAPS) is a complication affecting monochorionic twin or triplet pregnancies. It is a rare, chronic form of feto-fetal transfusion caused by the joining of fine blood vessels connecting the fetal circulations on the placenta. It presents when there are unequal blood counts between the twins in the womb. When TAPS occurs, the recipient twin is at risk for successively increasing blood count, called polycythaemia, and the donor twin for progressive blood loss, or anaemia. TAPS occurs without the differences in levels of amniotic fluids between the fetuses (polyhydramnios-oligohydramnios) that is usually seen in FFTS.# Recommendations for research
The guideline committee has made the following recommendations for research.
As part of the 2019 update, the guideline committee made an additional recommendation for research on the identification on twin anaemia polycythaemia sequence (TAPS). The committee removed 6 of the 2011 recommendations on screening for chromosomal conditions, screening for feto-fetal transfusion syndrome, defining fetal growth restriction, predicting and preventing spontaneous preterm birth, and perinatal and neonatal morbidity and mortality in babies born by elective birth.

# Key recommendations for research

## Screening to detect twin anaemia polycythaemia sequence
What is the most accurate prenatal screening marker for TAPS, including middle cerebral artery peak systolic velocity (MCAPSV)? 
For a short explanation of why the committee made the recommendation for research, see the rationale on diagnostic monitoring for twin anaemia polycythaemia sequence .
Full details of the evidence and the committee's discussion are in evidence review C: screening for TAPS.
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## Information and support
Does additional information and emotional support improve outcomes in twin and triplet pregnancies? 

## Specialist care
Does specialist antenatal care for women with twin and triplet pregnancies improve outcomes for women and their babies? 

## Indications for referral to a tertiary level fetal medicine centre
What is the incidence of monochorionic monoamniotic twin and triplet pregnancies, and what clinical management strategies are most effective in such pregnancies? 

# Other recommendations for research

## Gestational age
How should gestational age be estimated in twin and triplet pregnancies? 

## Chorionicity
What is the most accurate method of determining chorionicity in twin and triplet pregnancies at different gestational ages, and how does operator experience affect the accuracy of different methods? 

## Nutritional supplements
Is dietary supplementation with vitamins or minerals, or dietary manipulation in terms of calorie intake, effective in twin and triplet pregnancies? 

## Diet and lifestyle advice
Is dietary advice specific to twin and triplet pregnancies effective in improving maternal and fetal health and wellbeing? 

## Screening for structural abnormalities
When and how should screening for structural abnormalities be conducted in twin and triplet pregnancies? 

## Hypertension
Which clinical factors, laboratory screening tests, and ultrasound tests are predictive of hypertensive disorders in twin and triplet pregnancies? 

## Untargeted corticosteroids
What is the clinical and cost effectiveness, and safety, of routine antenatal administration of a single course of corticosteroids for women with twin and triplet pregnancies who are not in labour and in whom labour and birth are not imminent? 

## Indications for referral to a tertiary level fetal medicine centre
What is the clinical and cost effectiveness of referral to tertiary level fetal medicine centres for twin and triplet pregnancies complicated by discordant fetal growth, discordant fetal anomaly or discordant fetal death? # Rationale and impact
These sections briefly explain why the committee made the recommendations and how they might affect practice. They link to details of the evidence and a full description of the committee's discussion.

# Intrapartum care
Recommendation 1.3.6

## Why the committee made the recommendation
The committee recognised that the core multidisciplinary team recommended by the previous guideline (see recommendation 1.3.1) provides care during the antenatal period and would not be the same team providing intrapartum care. Because intrapartum care was added to the guideline update, they made a recommendation to clarify that healthcare professionals supporting women when they are giving birth should also have knowledge and experience in multiple pregnancy.

## How the recommendation might affect practice
The recommendation reinforces current practice.
Return to recommendation

# Screening for chromosomal conditions
Recommendations 1.4.3 to 1.4.8

## Why the committee made the recommendations
Since the 2011 guideline, the National Screening Committee's recommendations on screening for fetal chromosomal conditions have been published and have been implemented by the NHS fetal anomaly screening programme (FASP). These apply to women with both singleton and twin pregnancies, so the 2011 recommendations were replaced by a cross reference to this screening programme. The committee recognised that no current guidance exists for triplets so they retained a recommendation on triplets from the 2011 guideline. However, based on their expertise they decided this existing recommendation would apply only to screening in trichorionic triplets so they made an additional recommendation about dichorionic and monochorionic triplet pregnancies. Because of the complexity of screening these types of triplet pregnancies, this screening should only be carried out after referral to a tertiary level fetal medicine centre.

## How the recommendations might affect practice
The recommendations reinforce current best practice.
Return to recommendations

# Screening for preterm birth
Recommendations 1.4.13 to 1.4.15

## Why the committee made the recommendations
The committee agreed, based on their experience and expertise, that women should be given information about the higher risk of preterm birth in twin and triplet pregnancy compared with singleton pregnancy.
The committee retained the existing 2011 recommendations that fetal fibronectin testing and home uterine activity monitoring should not be used to predict the risk of spontaneous preterm birth because there was still no evidence suggesting they were accurate.

## Why the committee did not make a recommendation on cervical length screening in twin pregnancy
The evidence suggested that cervical length is a moderate predictor of spontaneous preterm birth in twin pregnancy. Although there were some inconsistencies between studies, the committee agreed they still supported the use of cervical length measurements to predict preterm birth in twin pregnancy. Establishing that a woman is at risk of preterm birth allows an intervention to be offered, and there is some evidence that vaginal progesterone may reduce this risk in women with a twin pregnancy. However, the committee was also aware that new evidence would be emerging about the use of vaginal progesterone in subgroups of women with a short cervix that could change their conclusions about its effectiveness. This uncertainty meant the committee could not recommend vaginal progesterone to prevent preterm birth. Because of this, the committee also decided they could not recommend cervical length screening in the absence of an effective intervention to offer women with a higher risk of preterm birth.

## How the recommendations might affect practice
The recommendations reinforce current best practice.
Return to recommendations

# Screening for fetal growth restriction and feto-fetal transfusion syndrome in the first trimester
Recommendation 1.4.16

## Why the committee made the recommendation
There was evidence that discordance in either crownrump length or nuchal translucency during the first trimester is not an accurate predictor of growth discordance in the second and third trimester. The committee discussed the evidence for other ultrasound screening measures in the first trimester and decided that because of its low quality they were not confident in recommending any screening tests in the first trimester.
The evidence showed that none of the first trimester screening tests were able to detect the risk of feto-fetal transfusion syndrome developing later in the pregnancy. Although there were uncertainties in this evidence, it was supported by the committee's clinical experience and current clinical practice.

## How the recommendation might affect practice
The recommendation reinforces current practice.
Return to recommendations

# Diagnostic monitoring for fetal growth restriction in dichorionic twin and trichorionic triplet pregnancies
Recommendations 1.4.17 to 1.4.23

## Why the committee made the recommendations
Based on evidence which showed that abdominal palpation and symphysisfundal height were not accurate measurements to diagnose fetal growth restriction, the committee recommended that these should not be used.
Fetal growth restriction is associated with perinatal mortality, morbidity and preterm birth. The committee agreed that monitoring using ultrasound scanning is essential to identify women in this high-risk group.
The evidence was limited on the frequency of ultrasound scanning for women with dichorionic twin pregnancies but, based on their expertise, the committee agreed that women with a dichorionic twin pregnancy should have scans no more than 28 days apart.
They also recommended ultrasound monitoring at least every 14 days for women with all types of triplet pregnancy (recommendations 1.4.19 and 1.4.32) because they are at higher risk of fetal growth restriction.
Based on both the evidence and their expertise, the committee recommended using at least 2 different biometric parameters as well as amniotic fluid level assessment to provide greater accuracy in calculating estimated fetal weight (EFW).
The Royal College of Obstetricians and Gynaecologists' Green Top guideline on monochorionic twin pregnancy recommends referring women 'for assessment and management in fetal medicine units with recognised relevant expertise' if there is an EFW discordance of more than 20%. In the committee's experience, this level of discordance should cause concern in all types of twin and triplet pregnancy and should prompt increased monitoring. However, they recommended instead increasing to weekly monitoring and adding the extra parameter of a doppler assessment. This would be equivalent to the specialist assessment recommended by the Green Top guideline because it would need to be carried out by the specialist core team (in line with recommendation 1.3.1) who have experience and knowledge of managing twin and triplet pregnancies. The committee agreed that this would not be inconsistent with the Green Top guideline.
The committee also agreed that the EFWs themselves should be taken into account. Based on the evidence and their expertise they recommended the 10th centile for gestational age as a threshold for concern that should prompt increased monitoring.
The evidence was inconclusive about an exact threshold for referral to a tertiary level fetal medicine centre, so based on their own experience the committee decided that an EFW discordance of 25% or more (along with an EFW below the 10th centile for gestational age) should warrant referral. At this level of discordance, there would be an increased risk of perinatal morbidity and mortality that should prompt intervention rather than increased assessment. The tertiary level fetal medicine centre would have the expertise to weigh up the benefits and risks of conservative management, birth or invasive fetal therapy to improve the chance of a positive pregnancy outcome.

## How the recommendations might affect practice
These recommendations are largely reinforcing current practice in twin pregnancy and should have a minimal impact on local ultrasound resourcing. They are consistent with other national and international guidance.
The recommendations to monitor all women with a triplet pregnancy at no more than 14day intervals (irrespective of chorionicity) are a change in practice, particularly for women with a trichorionic triamniotic pregnancy. For these women, previous recommendations suggested 4weekly scans. However, the change is justified because all types of triplet pregnancy are at high risk of fetal growth restriction. The recommendation should not have a significant impact on clinical resources because of the low number of women with a triplet pregnancy.
Return to recommendations

# Diagnostic monitoring for feto-fetal transfusion syndrome
Recommendations 1.4.24 to 1.4.29

## Why the committee made the recommendations
The committee agreed that feto-fetal transfusion syndrome is difficult to detect using amniotic fluid discordance before 16 weeks of pregnancy. After this stage, amniotic fluid levels have increased and differences between them can be used to diagnose feto-fetal transfusion syndrome. Monitoring fortnightly from 16 weeks should ensure that feto-fetal transfusion syndrome is diagnosed as early as possible. The committee decided based on their expertise  and on limited evidence from studies that conducted diagnostic scans after 24 weeks  that continuing fortnightly monitoring until birth would improve outcomes for women who develop feto-fetal transfusion syndrome later in pregnancy (although it is less common after 26 weeks). The committee also agreed that offering women with a monochorionic pregnancy scans at 14-day intervals means that the woman can be monitored efficiently for all the complications in recommendation 1.4.24 at each scan.
To support this frequency of monitoring, the committee also increased the number of reviews by the specialist obstetrician from at least 2 (in the 2011 guideline) to at least 5 for dichorionic and monochorionic triamniotic triplet pregnancies (recommendation 1.3.10). Dichorionic triamniotic triplets have an increased risk of adverse outcomes compared with monochorionic diamniotic twins if feto-fetal transfusion occurs. The risk of complications of monochorionicity, and of adverse outcomes if complications occur, is higher in triplets than in twins. More frequent review by the specialist obstetrician would ensure optimal critical assessment of ultrasound findings (including findings related to feto-fetal transfusion syndrome) and any need for more frequent monitoring.
The committee agreed that making sure the amniotic membrane is visible in the scan reduces the chance of measuring the same sac twice in error and improves accuracy in identifying a difference between the babies' amniotic fluid levels.
Based on their knowledge and experience, the committee agreed that women should be referred immediately to a tertiary level fetal medicine centre when differences in amniotic fluid levels meet the criteria for diagnosing feto-fetal transfusion syndrome. The clinical course of feto-fetal transfusion syndrome can be unpredictable so this would allow prompt assessment and early intervention. They also agreed that when differences in amniotic fluid levels are measured that do not yet meet the threshold for feto-fetal transfusion syndrome, women should be seen by their named specialist obstetrician for multiple pregnancy and offered more frequent monitoring, using doppler assessment to help detect feto-fetal transfusion syndrome as early as possible.

## How the recommendations might affect practice
Monitoring for feto-fetal transfusion syndrome from 16 weeks of pregnancy until birth is a change to current practice, in which monitoring is only carried out until week 24. Early detection would enable prompt management, and this would outweigh the cost of additional ultrasound.
Return to recommendations

# Diagnostic monitoring for fetal growth restriction in monochorionic twin and triplet pregnancy
Recommendations 1.4.30 to 1.4.36
A monochorionic twin or triplet pregnancy is one in which any of the babies share a placenta and a chorionic (outer) membrane. This includes monochorionic twins and dichorionic and monochorionic triplets.

## Why the committee made the recommendations
Based on evidence which showed that abdominal palpation and symphysisfundal height were not accurate measurements to diagnose fetal growth restriction, the committee recommended that these should not be used.
Fetal growth restriction is associated with perinatal mortality, morbidity and preterm birth. The committee agreed that monitoring using ultrasound scanning is essential to identify women in this high-risk group.
The evidence was limited on the frequency of ultrasound scanning for women with monochorionic pregnancies, so the committee used their expertise to make recommendations. They agreed that women with a monochorionic twin pregnancy need more frequent scans than women with a dichorionic twin pregnancy because they have a higher risk of severe growth discordance.
Scanning at no more than 14-day intervals would allow the woman to be referred promptly either to her specialist obstetrician for multiple pregnancy or to a tertiary level fetal medicine centre depending on the EFWs (see below). The committee also agreed that because women with a monochorionic pregnancy should be having scans at 14day intervals to monitor for feto-fetal transfusion syndrome, these timings mean they can be monitored for both of these complications at the same time (in line with recommendation 1.4.24).
The committee also recommended ultrasound monitoring at least every 14 days for women with all types of triplet pregnancy (recommendations 1.4.19 and 1.4.32) because they are at higher risk of fetal growth restriction.
Based on both the evidence and their expertise, the committee recommended using at least 2 different biometric parameters as well as amniotic fluid level assessment to provide greater accuracy in calculating EFW.
The Royal College of Obstetricians and Gynaecologists' Green Top guideline on monochorionic twin pregnancy recommends referring women 'for assessment and management in fetal medicine units with recognised relevant expertise' if there is an EFW discordance of more than 20%. The committee agreed with the Green Top guideline that this level should cause concern and prompt increased monitoring, but they recommended instead increasing to weekly monitoring and adding the extra parameter of a doppler assessment. This would be equivalent to the specialist assessment recommended by the Green Top guideline because it would need to be carried out by the specialist core team (in line with recommendation 1.3.1) who have experience and knowledge of managing twin and triplet pregnancies. The committee agreed that this would not be inconsistent with the Green Top guideline.
The committee also agreed that the estimated fetal weights themselves should be taken into account. Based on the evidence they recommended the 10th centile for gestational age as a threshold for concern that should prompt increased monitoring.
The evidence was inconclusive about an exact threshold for referral to a tertiary level fetal medicine centre, so based on their own experience the committee decided that an EFW discordance of 25% or more (along with an EFW below the 10th centile) should warrant referral. At this level of discordance, there would be an increased risk of perinatal morbidity and mortality that should prompt intervention rather than increased assessment. The tertiary level fetal medicine centre would have the expertise to weigh up the benefits and risks of conservative management, birth or invasive fetal therapy to try to improve the chance of a positive pregnancy outcome.

## How the recommendations might affect practice
These recommendations are largely reinforcing current practice in twin pregnancy and should have a minimal impact on local ultrasound resourcing. They are consistent with other national and international guidance.
The recommendation to monitor all women with a triplet pregnancy at no more than 14day intervals (irrespective of chorionicity) is a change in practice, particularly for women with a trichorionic triamniotic pregnancy. For these women, previous recommendations suggested 4weekly scans. However, the change is justified because all types of triplet pregnancy are at high risk of fetal growth restriction. The recommendation should not have a significant impact on clinical resources because of the low number of women with a triplet pregnancy.
Return to recommendations

# Diagnostic monitoring for twin anaemia polycythaemia sequence
Recommendations 1.4.37 and 1.4.38

## Why the committee made the recommendations
There was limited evidence for screening and diagnostic monitoring for twin anaemia polycythaemia sequence (TAPS). The committee discussed, based on their expertise, that there is also limited evidence on the natural history of spontaneous TAPS and effective interventions for it in uncomplicated monochorionic pregnancies. They agreed that its incidence is likely to be low, so they could not recommend screening for it in women whose monochorionic pregnancy is uncomplicated.
The committee agreed that monitoring would be beneficial for women with the complications in recommendations 1.4.37 and 1.4.38. They recommended screening for TAPS in this population for 2 reasons:
Complicated monochorionic pregnancies have an increased risk of fetal and neonatal death and morbidity. Diagnosing TAPS as a further complication is likely to influence how the woman's pregnancy is managed, including the timing of preterm birth.
Advanced TAPS (stages 3 and 4) is associated with abnormal fetal umbilical artery and ductus venosus doppler parameters, or signs of fetal cardiac failure in the anaemic baby. These can also occur in a number of other conditions, so the diagnosis of severe TAPS (either alone or as a comorbidity) may be missed if it is not specifically screened for.
The committee concluded that for women who have a pregnancy in which TAPS is a comorbid complication or is of advanced stage, the risk to the babies without diagnosis and intervention is likely to be greater than the potential harms of interventions. These include preterm birth or potential inutero therapies, such as inutero transfusion, in pre-viable or extremely premature pregnancies.
The committee agreed that when TAPS is suspected, women should be referred to a tertiary level fetal medicine centre. They felt that the benefits of managing complicated monochorionic pregnancies in this setting would outweigh the potential disadvantages of inconvenience of travel and transfer to units away from home. The committee decided not to specify diagnostic criteria because they wanted to emphasise the importance of referral to a tertiary level referral centre when TAPS is suspected, so that decisions about further assessment and management can be made with each individual woman.
Given the limited evidence on the diagnostic accuracy of middle cerebral artery peak systolic velocity (MCAPSV) for all types of monochorionic twins, regardless of complications, and uncertainties about the natural history of TAPS and its management, the committee decided to make a recommendation for research on screening to detect twin anaemia polycythaemia sequence to inform future guidance.

## How the recommendations might affect practice
The recommendation may increase the number of assessments of women with complicated monochorionic pregnancies and referral for appropriate management. However, the committee agreed that any increase in referrals would be offset by the benefits of better detection and management of complicated monochorionic pregnancies.
Return to recommendations

# Preventing preterm birth
Recommendations 1.5.1 and 1.5.2

## Why the committee made the recommendations
The evidence for intramuscular progesterone in the prevention of spontaneous preterm birth showed it had no clinical benefit and, in some instances, had negative or unpleasant side effects, so it was not recommended.
The committee retained the existing 2011 recommendation that arabin pessary, bed rest, cervical cerclage and oral tocolytics should not be used routinely to prevent spontaneous preterm birth because there was still no evidence to support their use.

## Why the committee did not make a recommendation on vaginal progesterone
The committee decided not to make recommendations on the use of vaginal progesterone to prevent preterm birth because they knew about evidence that would be emerging about the use of progesterone in subgroups of women with a short cervix that could change their conclusions about its effectiveness. This also meant the committee preferred not to recommend cervical length screening (see the rationale section on cervical length screening in twin pregnancy). NICE will carry out an exceptional update based on the new evidence when it becomes available.

## How the recommendations might affect practice
The recommendations reinforce current practice.
Return to recommendations

# Planning birth: information and support
Recommendations 1.8.1 to 1.8.3

## Why the committee made the recommendations
The committee discussed the importance of providing care that is woman-centred, in which shared decision-making between the woman and her healthcare professional is essential. The committee agreed on the topics that need to be discussed with women to explain the available options and find out their wishes. Information needs to be tailored to each woman's pregnancy because some twin and triplet pregnancies carry more risks than others.
The committee acknowledged equality considerations for women who may have additional needs (such as needing an interpreter) in the context of providing information and communication. They cross-referred to NICE's guideline on patient experience in adult NHS services, which describes general good practice on how to do this.
Return to recommendations

# Timing of birth
Recommendations 1.9.1 to 1.9.12

## Why the committee made the recommendations
The committee agreed that it was critical to give women the information they need to participate in shared decisions about when their babies are born. This includes explaining the known risk of spontaneous preterm birth in twin and triplet pregnancy and its possible consequences, such as admission to a neonatal unit. The committee retained this advice from the 2011 guideline because it was consistent with their experience and knowledge. They agreed that this information is important for planning the timing of birth.
Women also need to know why it is recommended for them to have a planned birth by a particular week of pregnancy (also see when to offer planned birth). There is a trade-off between clinical benefits and harms when women have not given birth spontaneously by a given gestational age. These include the risks of neonatal mortality and morbidity associated with planned birth compared with the risks of stillbirth from continued pregnancy. The committee agreed that both timing and mode of birth should be discussed with women in the context of these potential risks. Women can use this advice to make an informed choice.
There was not enough good evidence to conclusively identify the optimal timing of birth according to chorionicity and amnionicity, so the committee also used their expertise and experience to make recommendations.
Evidence suggests a consistently higher fetal death rate (at all gestational ages) in monochorionic twin pregnancies than in dichorionic twin pregnancies. The committee therefore recommended earlier planned birth, at 36 weeks, for women with a monochorionic diamniotic pregnancy to reflect the higher risk and complexity of this type of pregnancy. This was consistent with the 2011 guideline and therefore corresponds to current clinical practice.
The committee also clarified the timing of birth for monochorionic monoamniotic twins, which was not explicitly covered by the 2011 guideline  the previous guideline did not divide monochorionic twins into diamniotic or monoamniotic groups. Based on some evidence and their own knowledge and experience, the committee recommended offering planned birth between 32+0 and 33+6 weeks because this timing did not appear to be associated with an increased risk of serious neonatal adverse outcomes.
The committee clarified the recommendations from the 2011 guideline by considering triplet pregnancies by type rather than as a single group. No evidence was found on timing of birth in triplet pregnancy but the committee agreed based on their own clinical experience that continuing an uncomplicated trichorionic triamniotic or a dichorionic triamniotic triplet pregnancy beyond 35+6 weeks of pregnancy would lead to an increased risk of fetal death (recommendation 1.9.7). Planned birth should therefore be offered at 35 weeks (recommendation 1.9.10).
Because of significant risks for the babies in complicated twin and triplet pregnancies, and the rareness of monochorionic triamniotic triplet pregnancies and triplet pregnancies with a shared amnion, timing of birth should be assessed and discussed individually (recommendations 1.9.8 and 1.9.11).
The committee highlighted that women's choice needs to be respected and that if a woman declines planned birth at the recommended time, she should be offered weekly appointments to minimise risk, monitor progress and help to identify any complications as soon as possible.

## How the recommendations might affect practice
The recommendations clarify the timing of when women with a monochorionic monoamniotic pregnancy should be offered planned birth. Although this is a change from the 2011 guideline, it reinforces current practice.
Return to recommendations

# Mode of birth

## Why the committee made the recommendations
Recommendations 1.10.1 to 1.10.5
For women who are more than 32 weeks pregnant and have an uncomplicated pregnancy, the evidence showed there is no significant difference in risk between vaginal birth and caesarean section, both for the woman and her babies. The committee's experience supported this, so they agreed that healthcare professionals should explain this to the woman and support her choice as long as the conditions in recommendation 1.10.1 are met and the first baby is in a head-first position.
There was only limited evidence about mode of birth when the first baby is not head first. The committee agreed that in their clinical experience, this carries a higher risk of problems such as cord accidents during birth. Because of this, a caesarean section is the safest option to offer women after 32 weeks and for women in established preterm labour between 26 and 32 weeks.
According to the evidence, not all women give birth according to their birth plan. The committee decided it was important to explain this to women so that they are prepared for the possibility of not giving birth in the way they prefer.
Recommendations 1.10.6 and 1.10.7
Monochorionic monoamniotic twin pregnancies and triplet pregnancies are the least common and highest-risk types of pregnancy and evidence about mode of birth was limited for these women. However, the committee agreed from their experience that caesarean section should be the preferred option and should be offered at the time the birth is planned to happen or after the diagnosis of established labour. If the first twin is close to being born vaginally there can be risks for the babies, so the committee decided that senior obstetric assessment would be needed.

## How the recommendations might affect practice
The recommendations largely reflect current practice. Supporting the woman's preferred mode of birth might increase the number of planned vaginal births, which may reduce costs. This is likely to be partly offset by the fact that a proportion of these women would go on to give birth by caesarean section for one or both twins.
Return to recommendations

# Fetal monitoring during labour in twin pregnancy
Recommendations 1.11.1 to 1.11.21

## Why the committee made the recommendations
There was no evidence on the most effective method of fetal monitoring in labour for improving outcomes in women with a twin pregnancy and their babies, so the committee used their expertise and experience along with NICE guidance on fetal monitoring in singleton pregnancy (NICE's guideline on intrapartum care for healthy women and babies) to make recommendations. They agreed that clinically it is well recognised that twins are at increased risk of complications during labour, especially the second twin, so they recommended continuous fetal monitoring. Continuous cardiotocography monitoring is the only modality that can assess both twin fetal heart rates simultaneously during established labour.
The committee agreed on the importance of explaining to women the lack of evidence about monitoring with cardiotocography specifically in twins, and that recommendations are based on NICE guidance for singleton pregnancy (intrapartum care for healthy women and babies). Healthcare professionals should provide a detailed explanation of what cardiotocography involves and why it is used and give women a chance to discuss their wishes and concerns. Recommending this before 28 weeks gives women time to make an informed decision and takes into account the fact that many twins are born prematurely.
The committee recommended offering continuous cardiotocography to women in established labour with a twin pregnancy over 26 weeks because at this gestational age, neonatal survival rates improve and the risks of neonatal morbidity from preterm birth are falling. The advantages of using cardiotocography over intermittent auscultation monitoring include the ability to assess baseline variability and monitor continuously.
Performing a portable ultrasound (bedside) scan at the start of established labour not only helps to confirm which is the first and which the second twin and locate the fetal hearts but also confirms presentation  malpresentation is more common in twin pregnancy than singleton pregnancy and an emergency caesarean section may be indicated if the first twin presents in the breech position.
The committee recommended involving a senior obstetrician to decide how twins are monitored in established extreme premature labour (23+0 to 25+6 weeks of pregnancy) in line with NICE's guideline on premature labour and birth in singleton pregnancies.
The committee recommended dual channel monitors to make sure both fetal heart rates could be monitored and displayed accurately at the same time on the same record during labour. Maternal pulse monitoring should be displayed on the same continuous cardiotocography trace to ensure 2 fetal heart rates were being recorded (without mistaking the maternal heart rate for a fetal heart rate).
The committee recommended classifying and interpreting cardiotocography in a way that is broadly consistent with the NICE guideline on intrapartum care for healthy women and babies, but with additional considerations specific to twins. These include regarding twin pregnancy as a fetal clinical risk factor when classifying a cardiotocograph finding as 'abnormal' or 'non-reassuring'. This would result in a lower threshold for classifying a cardiotocograph as pathological.
Failing to successfully monitor one or both babies could lead to adverse perinatal outcomes so the committee recommended involving a senior healthcare professional. They also recommended applying a fetal scalp electrode to the first baby while continuing abdominal monitoring of the second baby if abdominal monitoring is unsuccessful or there are concerns about synchronicity of the fetal hearts. This should only be carried out after 34 weeks of pregnancy and if there are no contraindications such as HIV, hepatitis or maternal thrombocytopenia.
If there is 'suspicious' cardiotocography in the first baby during established labour, the committee recommended involving a senior healthcare professional to help manage reversible causes such as dehydration, infection or positional loss of contact, before applying a fetal scalp electrode to the first baby (in the absence of contraindications) while continuing abdominal monitoring of the second baby.
In case of 'pathological' cardiotocography in the first baby, a senior healthcare professional should discuss with the woman using fetal blood sampling in the first baby if the benefits are likely to outweigh the potential risks  these include avoiding a second-stage caesarean section, which increases maternal morbidity and mortality.
After the first baby is born, cardiotocographic monitoring of the second baby should continue to detect any 'suspicious' or 'pathological' cardiotocography that could lead to the need for a caesarean section.
The committee did not make recommendations for women with a triplet pregnancy because most of these women give birth by caesarean section. Monitoring in labour would therefore be rare and decisions would be made on an individual basis.

## How the recommendations might affect practice
The recommendations are consistent with the NICE guideline on intrapartum care for healthy women and babies taking into account the twin-specific measures. It is not anticipated that the recommendations will lead to major changes in current clinical practice.
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# Analgesia
Recommendations 1.12.1 to 1.12.3

## Why the committee made the recommendations
There is limited evidence on analgesia in labour for women with a twin pregnancy, and no evidence for women with a triplet pregnancy, so the committee used their expertise and experience along with the very limited evidence to make recommendations. They agreed that there is variation in practice in relation to when healthcare professionals discuss analgesia and anaesthesia with women and what they should discuss, so they specified when this should happen during pregnancy and what to cover.
Women with a twin or triplet pregnancy have an increased risk of intervention in labour, including assisted birth or caesarean section for one or more of the babies, and additional internal manoeuvres. Having an epidural in place allows analgesia or anaesthesia to be given quickly when it is needed, reducing the potential need for emergency general anaesthesia.
The limited evidence suggested that having an epidural in place also reduces the need for emergency caesarean section for the second twin after vaginal birth of the first twin, possibly by allowing more effective internal manoeuvres to allow the second twin to be born vaginally.

## How the recommendations might affect practice
The recommendations reinforce current best practice.
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# Managing the third stage of labour
Recommendations 1.13.1 to 1.13.9

## Why the committee made the recommendations
The evidence was very limited, so the committee used their clinical expertise and experience to make recommendations. Multiple pregnancy is a risk factor for postpartum haemorrhage (see NICE's guideline on intrapartum care for healthy women and babies) because of over-distension of the uterus and enlarged placenta(s). The committee agreed that healthcare professionals should explain this to women in the antenatal period and assess and re-evaluate each woman's individual risk as her pregnancy progresses.
Because of the risk of postpartum haemorrhage, the committee agreed that active management of the third stage of labour using uterotonics should be offered to all women, and physiological management should not be offered.
It is already well-established as current practice and is supported by the committee's experience that when women have more than 1 risk factor for postpartum haemorrhage, additional uterotonics can reduce this risk. There is no clear evidence on the comparative effectiveness of different uterotonics in twin or triplet pregnancy. Each uterotonic has risk factors and contraindications, so the committee did not recommend a specific one.
The committee agreed on the importance of having existing intravenous access and blood products readily available in case a postpartum haemorrhage does occur.

## How the recommendations might affect practice
The recommendations reinforce current best practice.
Return to recommendations# Context
Twins or triplets occur in approximately 1 in 60 pregnancies (16 in every 1,000 women giving birth in 2015 had a multiple birth), and 3% of live-born babies are from multiple gestations. The incidence of multiple births has risen in the past 30 years. This is due mainly to increasing use of assisted reproduction techniques, including in vitro fertilisation (IVF), and also to changing demographics as women defer pregnancy and twins are more common at later ages (102 in every 1,000 women giving birth in 2015 were aged 45 or over).
Women with a twin or triplet pregnancy are at higher risk compared with women with a singleton pregnancy. Adverse outcomes are more likely, both for the woman and her babies, during the prenatal and intrapartum periods. Because of this, women need increased monitoring and more contact with healthcare professionals during their pregnancy.
Assessment and planning start as soon as the twin or triplet pregnancy is detected and continue throughout pregnancy at each antenatal contact. Determining the chorionicity and amnionicity of the pregnancy allows the risk to be stratified and the number of antenatal visits and ultrasound examinations to be planned. It is important that ultrasound surveillance is carefully scheduled to monitor for complications including selective fetal growth restriction, feto-fetal transfusion syndrome and twin anaemia polycythaemia sequence (TAPS).
Identifying complications earlier means that decisions can be made promptly about referring the woman to a tertiary level fetal medicine centre. It also informs discussions with women in their second and third trimesters about their hopes and wishes in relation to timing and mode of birth, and the management of the intrapartum period (including fetal monitoring, analgesia and the third stage of labour).
This guideline replaces the previous NICE guideline on multiple pregnancy (CG129). The surveillance process found new evidence and identified a need to include intrapartum care, an area that was not included in the original guideline. In current practice, a significant proportion of multiple pregnancy losses occur intrapartum and the risk of adverse perinatal outcomes is greater in multiple than in singleton pregnancies.
The guideline updates recommendations on screening and monitoring for selective fetal growth restriction and feto-fetal transfusion syndrome, and makes new recommendations on screening and monitoring for TAPS; screening for and preventing preterm birth; and timing of birth. New recommendations on intrapartum care cover mode of birth, fetal monitoring, analgesia and managing the third stage of labour.