Preterm labor resident survival guide
Synonyms and keywords:Preterm delivery, Premature labour, Early delivery, Premature birth, Premature labor, Pre term birth

# Overview
Preterm labor is defined as labor that occurs between after 20 and before 37 weeks of gestation. When preterm labor occurs prior to 33 weeks of gestation, it is called early preterm labor and late preterm labor occurs between 34 and 36 weeks of gestation.Stress, infection, placental abruption, placenta previa, substance use, prior history of preterm birth or abortion, inadequate prenatal care, smoking, maternal age 40, poor nutrition, low body mass index, fetal anomaly, fetal growth restriction, oligohydramnios, polyhydramnios, vaginal bleeding, premature preterm rupture of membranes (PPROM) are few factors that contribute to preterm labor.It is one of the main cause of neonatal death. Neonates born preterm are at an increased risk of neurodevelopmental disorders, such as cerebral palsy, intellectual disabilities and vision/hearing impairments.Most of the preterm births occur after the spontaneous onset of labor, whereas the rest of the cases are related to maternal or fetal complications, such as preeclampsia or intrauterine growth restriction.

# Causes
Intra-amniotic infection so far has only been shown to cause preterm delivery. The other factors are being associated based on reports by clinical, epidemiologic, placental pathologic, or experimental studies.Intra-amniotic infections can be subclinical. One in four preterm infants are born due to this cause.
- Infection:
The most frequent route is the ascending pathway, but hematogenous dissemination can occur.
Microorganisms are recognized by pattern recognition receptors, such as toll-like receptors (TLRs).
TLRs stimulate the production of chemokines (IL-8, C-C motif ligand 2 (CCL2), etc.), cytokines (IL-1b, TNF-a, etc), prostaglandins and proteases which activate the quiescent myometrium and stimulates parturition.
In 30% of cases of intra-amniotic infection, bacteria can be found in the fetal circulation which causes fetal systemic inflammatory response. These fetuses are at risk for long-term complications, such as cerebral palsy and chronic lung disease, which emphasizes that these complications may not only occur due to immaturity but also inflammatory response.
- The most frequent route is the ascending pathway, but hematogenous dissemination can occur.
- Microorganisms are recognized by pattern recognition receptors, such as toll-like receptors (TLRs).
- TLRs stimulate the production of chemokines (IL-8, C-C motif ligand 2 (CCL2), etc.), cytokines (IL-1b, TNF-a, etc), prostaglandins and proteases which activate the quiescent myometrium and stimulates parturition.
- In 30% of cases of intra-amniotic infection, bacteria can be found in the fetal circulation which causes fetal systemic inflammatory response. These fetuses are at risk for long-term complications, such as cerebral palsy and chronic lung disease, which emphasizes that these complications may not only occur due to immaturity but also inflammatory response.
- Uterine over distension
- Decidual senescence
- Vascular disorders
- Stress
- Cervical disease
- Decline in progesterone action
- Breakdown in maternal-fetal tolerance.
- Placental abruption, Placenta previa
- Smoking
- Maternal age 40 
- Poor nutrition, low body mass index
- Fetal anomaly
- Fetal growth restriction, oligohydramnios, polyhydramnios
- Vaginal bleeding
- Premature preterm rupture of membranes (PPROM)
- Environmental factors

# Diagnosis
Shown below is an algorithm summarizing the diagnosis of Preterm labor:
Abbreviations: BP: Blood pressure; RR=Respiratory rate;
HR=Heart Rate, PROM= Premature rupture of membranes; AFV=  Amniotic fluid volume

# Treatment
Shown below is an algorithm summarizing the treatment of Preterm labor :
Tocolytics used in preterm labor:

# Dos
- Healthy pregnancy habits may help to reduce the risk of preterm labor, such as :
Good prenatal medical care
Staying hydrated
Avoiding smoking and alcohol
Eating nutritious foods and taking prenatal vitamins
- Good prenatal medical care
- Staying hydrated
- Avoiding smoking and alcohol
- Eating nutritious foods and taking prenatal vitamins
- If the woman has any symptoms of preterm labor such as contractions, cramps, back pain, or leaking of fluid from the vagina, she should contact her healthcare provider right away.
- Cervical cerclage plays an important role to prevent preterm labor. It can be used in women with a history of recurrent mid-trimester pregnancy losses, women diagnosed with cervical insufficiency, woman with a short cervix( cervical length of <25 mm),incompetent cervix and threatened preterm labor.
- Progesterone supplementation causes uterine inactivity which may block preterm labor.Progesterone levels decreases before the onset of labor which leads to parturition, so giving progesterone to the mother with delay the onset of labor.

# Don'ts
- If the woman smokes, she should get help to stop smoking before getting pregnant.
- Heavy physical activity should be avoided.