Preterm Labor: Risk Factors and Symptoms

• Preterm labor is defined as labor that begins before 37 weeks of gestation.

Risk Factors

• Prior preterm birth is a significant risk factor.
• Multiple gestations (twins, triplets, etc.) increase the risk.
• Uterine abnormalities, such as a bicornuate uterus, can contribute.
• Cervical insufficiency or a short cervix is associated with preterm labor.
• Infections, including urinary tract infections (UTIs) and vaginal infections, can trigger preterm labor.
• Chronic health conditions in the mother, such as diabetes or hypertension, elevate the risk.
• Smoking, drug use, and alcohol consumption during pregnancy are linked to preterm labor.
• In vitro fertilization (IVF) pregnancies have a higher risk of preterm labor.
• Low socioeconomic status and limited access to prenatal care can increase the risk.
• Maternal age (very young or older mothers) is a risk factor.
• Stress and lack of social support can contribute to preterm labor.

Symptoms

• Regular or frequent contractions that may or may not be painful are a primary symptom.
• Lower back pain that feels like a constant dull ache or intermittent pain is a symptom.
• Pelvic pressure, feeling like the baby is pushing down, can occur.
• Vaginal discharge changes, including increased amount, watery discharge, or bloody discharge are symptoms.
• Abdominal cramping, similar to menstrual cramps, may be present.
• Rupture of membranes (water breaking) is a clear sign of preterm labor.

Diagnosis

• Gestational age assessment is crucial for diagnosing preterm labor.
• Fetal fibronectin (fFN) test can help predict the likelihood of preterm labor.
• A negative fFN test suggests that preterm labor is unlikely in the next 1-2 weeks.
• Cervical length measurement via transvaginal ultrasound is used to assess the risk.
• A short cervix (less than 25 mm) indicates a higher risk.
• Monitoring uterine contractions and fetal heart rate is essential.
• Evaluation for infections, such as urinary tract infections (UTIs) or bacterial vaginosis, is important.

Management

• Tocolytic medications are used to temporarily stop or slow down contractions.
  • Examples include:
    • Magnesium sulfate
    • Nifedipine
    • Terbutaline
    • Indomethacin (used cautiously due to potential fetal side effects)
• Corticosteroids, such as betamethasone or dexamethasone, are administered to the mother to help mature the baby's lungs.
  • These are typically given between 24 and 34 weeks of gestation.
• Antibiotics are used if an infection is present.
• Magnesium sulfate is also used for neuroprotection of the fetus, reducing the risk of cerebral palsy.
• Bed rest is sometimes recommended, although its effectiveness is debated.
• Hydration helps to prevent contractions caused by dehydration.

Prevention

• Progesterone supplementation is often given to women with a history of preterm birth or a short cervix.
• Cerclage, a stitch placed in the cervix to provide support, may be used in women with cervical insufficiency.
• Regular prenatal care helps identify and manage risk factors.
• Education about the signs and symptoms of preterm labor is crucial.
• Smoking cessation, avoiding drug use, and limiting alcohol consumption can reduce the risk.
• Management of chronic health conditions can lower the risk of preterm labor.
• Treatment of infections promptly can prevent preterm labor.
• Avoiding unnecessary medical interventions, such as elective inductions before 39 weeks, can help.

Complications

• Prematurity-related complications in the newborn are common.
  • Respiratory distress syndrome (RDS) due to immature lungs is an example.
  • Intraventricular hemorrhage (IVH), bleeding in the brain, is an example.
  • Necrotizing enterocolitis (NEC), a serious intestinal problem, is an example.
  • Sepsis, a blood infection, is an example.
• Long-term disabilities in the child are possible.
  • Cerebral palsy is an example.
  • Developmental delays are an example.
  • Vision and hearing problems are examples.
• Maternal complications can occur:
  • Risk of infection
  • Hemorrhage
  • Need for cesarean delivery

Neonatal Outcomes

• Respiratory distress syndrome (RDS) is a common complication due to immature lungs.
• Bronchopulmonary dysplasia (BPD) is a chronic lung disease that can develop in premature infants.
• Intraventricular hemorrhage (IVH) can lead to long-term neurological problems.
• Necrotizing enterocolitis (NEC) is a severe intestinal disease.
• Retinopathy of prematurity (ROP) can cause vision problems.
• Increased risk of infections due to immature immune systems is a concern.
• Difficulty with feeding and maintaining body temperature occur often.
• Long-term developmental delays and disabilities are possible.

Tocolytic Medications

• Magnesium Sulfate
  • Mechanism: CNS depressant and smooth muscle relaxant
  • Side Effects: Flushing, headache, muscle weakness, respiratory depression
  • Monitoring: Deep tendon reflexes, respiratory rate, urine output, magnesium levels
• Nifedipine
  • Mechanism: Calcium channel blocker, inhibits uterine contractions
  • Side Effects: Hypotension, headache, dizziness, nausea, flushing
  • Cautions: Avoid use with magnesium sulfate to prevent severe hypotension
• Terbutaline
  • Mechanism: Beta-adrenergic agonist, relaxes uterine smooth muscle
  • Side Effects: Tachycardia, palpitations, tremor, hyperglycemia
  • Cautions: Can cause maternal cardiac problems; use is limited due to side effects
• Indomethacin
  • Mechanism: Prostaglandin synthetase inhibitor, reduces prostaglandin production
  • Side Effects: Premature closure of ductus arteriosus (especially after 32 weeks), oligohydramnios
  • Cautions: Limited use due to fetal side effects; typically used before 32 weeks gestation

Corticosteroids

• Betamethasone and Dexamethasone:
  • Mechanism: Accelerate fetal lung maturation by promoting surfactant production
  • Administration: Typically given as two doses, 24 hours apart
  • Benefits: Reduces the risk of RDS, IVH, and neonatal mortality
  • Timing: Most effective when given between 24 and 34 weeks of gestation

Learn about preterm labor, defined as labor before 37 weeks of gestation. Key risk factors include prior preterm birth, multiple gestations, uterine abnormalities, and infections. Recognizing symptoms and understanding risks is crucial for prevention and management.