What are the signs and symptoms of preterm labor?

Signs and Symptoms of Preterm Labor

Preterm labor is characterized by regular, painful uterine contractions accompanied by cervical change (dilation and/or effacement) that occurs before 37 weeks of gestation. 1

Primary Clinical Manifestations

• Regular uterine contractions - Unlike Braxton-Hicks contractions, preterm labor contractions:

  • Are regular in timing
  • Are painful (not just uncomfortable)
  • Do not subside with rest
  • May increase in frequency and intensity 1

• Cervical changes - Essential for diagnosis:

  • Progressive cervical dilation
  • Cervical effacement (thinning)
  • Note: Assessment may be challenging in certain populations (e.g., women with skeletal dysplasia) due to anatomical differences 1

Associated Symptoms

• Low, dull backache that may be constant or intermittent
• Pelvic or lower abdominal pressure (sensation of the baby pushing down)
• Abdominal cramping with or without diarrhea
• Increase or change in vaginal discharge (may become watery, mucous-like, or bloody)
• Rupture of membranes (leaking or gushing of fluid from vagina)

Diagnostic Criteria

The diagnosis of preterm labor requires:

1. Regular uterine contractions (≥4 in 20 minutes or ≥8 in 60 minutes)
2. Documented cervical change
3. Gestational age between 20 0/7 weeks and 36 6/7 weeks 1

Risk Assessment

Women with a history of spontaneous preterm delivery are 1.5-2 times more likely to experience subsequent preterm delivery 2. Other risk factors include:

• Multiple gestation
• Uterine anomalies
• Cervical insufficiency
• Previous cervical surgery
• Vaginal bleeding
• Intrauterine infection

Management Considerations

When preterm labor is suspected:

1. Immediate evaluation is critical as less than 10% of women with clinical diagnosis will deliver within 7 days of presentation 2

2. Tocolytic therapy may be considered to:

   • Allow time for corticosteroid administration
   • Facilitate maternal transfer to a tertiary care facility
   • Common agents include calcium channel blockers, prostaglandin inhibitors, and magnesium sulfate 1, 3

3. Corticosteroid administration for fetal lung maturity between 24-34 weeks gestation - the only intervention proven to reduce neonatal mortality 2

4. Magnesium sulfate for neuroprotection when delivery is imminent before 32 weeks 3, 2

Important Distinctions

• Braxton-Hicks vs. Preterm Labor: Braxton-Hicks contractions are irregular, generally uncomfortable but not painful, and subside with rest or hydration 1

• False vs. True Labor: In false labor, contractions do not cause progressive cervical change, which is the hallmark of true labor 1

Pitfalls to Avoid

1. Delayed recognition - Subtle symptoms may be dismissed, delaying critical interventions

2. Overdiagnosis - Not all uterine activity represents true preterm labor; cervical change is essential for diagnosis

3. Inappropriate fluid management - Careful attention to fluid administration is needed, especially in women with certain medical conditions 1

4. Failure to consider infection - At least 40% of preterm births are associated with intrauterine infection 4

Early recognition and appropriate management of preterm labor are essential to improve maternal and neonatal outcomes, as preterm birth remains the leading cause of neonatal morbidity and mortality in the United States 5, 2.