Unequal Placental Sharing in Monochorionic Diamniotic Twins: an Observational Study

Study Overview
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Brief Summary
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This is an observational study in 3 cohorts of monochorionic diamniotic (MCDA) twins. The aim of the study is to assess whether unequal placental sharing can be predicted in pregnancy and whether it is predictive of pregnancy outcome.

Detailed Description
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In all cohorts, serial ultrasound will be performed during pregnancy. MRI will be offered once during pregnancy. After delivery, placental examination will be performed. In unselected MCDA twins, the investigators will assess the relationship between unequal placental sharing and the risk of fetal or neonatal loss. The investigators will also establish whether umbilical vein measurements or MRI can be used to predict placental sharing. In cases complicated by twin-to-twin transfusion syndrome (TTTS), the investigators will look at the association between unequal placental sharing and intrauterine fetal demise after laser surgery. In cases complicated by selective intra-uterine growth restriction (sIUGR), the the relationship between unequal placental sharing and the risk of fetal or neonatal loss and birth prior to 34 weeks will be assessed. Furthermore, data on neurological outcome at 2 years of age in all cohorts will be collected.

Official Title
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Unequal Placental Sharing in Monochorionic Diamniotic Twins: an Observational Study to Investigate Prediction and Outcome: the TWINSHARE Study

Conditions
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Monochorionic Twins

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: MCDA cohort Ongoing monochorionic diamniotic twin pregnancy between 11 and 14 weeks, as determined by the crown rump length of the larger twin in spontaneous conceptions and by the date of insemination or embryonic age at replacement in pregnancies resulting from subfertility treatment Women aged 18 years or more, who are able to consent Written informed consent to participate in this study, forms being approved by the Ethical Committees TTTS cohort Monochorionic diamniotic twin pregnancy, with gestational age defined in the first trimester as mentioned above Complicated by TTTS according to the definition used in the Quintero staging of TTTS (DVP of donor < 2 cm and DVP of receptor > 8 cm before 20 weeks or > 10 cm after 20 weeks Undergoing laser surgery for TTTS Women aged 18 years or more, who are able to consent Written informed consent to participate in this study, forms being approved by the Ethical Committees sIUGR cohort Monochorionic diamniotic twin pregnancy, with gestational age defined in the first trimester as mentioned above Complicated by sIUGR defined as a discordance in EFW of ≥ 20%, with the percentage of discordance being calculated as (EFW larger twin - EFW smaller twin)/EFW larger twin x 100. Women aged 18 years or more, who are able to consent Written informed consent to participate in this study, forms being approved by the Ethical Committees Exclusion Criteria: Age < 18 years Inability to consent

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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Female

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| MCDA cohort<br>Unselected monochorionic diamniotic (MCDA) twin pregnancies, included between 11 and 14 weeks of gestation | |
| TTTS cohort<br>Pregnancies complicated by twin-twin transfusion syndrome (TTTS) undergoing laser treatment, included at the time of diagnosis or referral | |
| sIUGR cohort<br>Pregnancies complicated by selective intrauterine growth restriction (sIUGR), included at the time of diagnosis or referral. We define sIUGR as a discordance in estimated fetal weight of ≥ 20%. | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| MCDA cohort: the association between unequal sharing and risk of fetal or neonatal loss (assessed by review of obstetric and pediatric records) |  | 2 weeks after expected date of birth | 
| TTTS cohort: the association between unequal sharing and intrauterine fetal death (assessed by review of obstetric records) |  | 2 weeks after expected date of birth | 
| sIUGR cohort: the association between unequal sharing and risk of fetal or neonatal loss and birth prior to 34 weeks (assessed by review of obstetric and pediatric records) |  | 2 weeks after expected date of birth | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The correlation between prenatal ultrasound and MRI variables and placental sharing as assessed by postnatal imaging (all cohorts) |  | 2 weeks after expected date of birth | 
| The association between unequal sharing and intact survival (all cohorts) (assessed by review of obstetric and pediatric records and parent questionnaire) |  | 2 years after expected date of birth | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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monochorionic, placental sharing