Preterm Labor

Preterm Labor: Cervical changes and regular UCs occurring between 20 weeks and 37 weeks of gestation.
Preterm Birth: Birth before 37 weeks gestation.
Fragility of Premature Babies:
- Babies born at 28 weeks are more fragile than those born at 33 weeks.
- There exists a distinction between being premature and being low birth weight or growth restricted.

Neonatal Mortality: Approximately 70% of neonatal deaths are due to prematurity or its sequelae.
Long-term Effects: May develop long-term neurological deficits.

Infections: Primary cause of preterm labor; includes UTIs and vaginal infections. (Only definitive cause)
Incompetent Cervix: Short cervical length diagnosed via transvaginal ultrasound.
Bleeding in 2nd Trimester: Can lead to uterine irritability.
Multiple Gestations: Overdistention theory suggests that the more babies there are, the higher the chance of preterm labor due to uterine stretch.
Ethnic Disparities: Higher incidence of preterm labor noted in non-white populations.
Premature Rupture of Membranes (PPROM): Significant precursor to preterm labor but not all cases lead to delivery.
Low Pre-pregnancy Weight/BMI: Poor nutrition tied to lower weight and higher risk of preterm labor.
Socioeconomic Factors: Access to healthcare and nutritional foods highly impacts outcomes.
Physically Demanding Work: Jobs such as nursing and waiting tables are associated with preterm labor.

Incompetent Cervix: Cervix shortens or opens prematurely r/t structural problems.
Measurement: Done typically between 15 to 28 weeks, normal cervical length should be approximately 30 mm for stability.
Importance of measuring cervical length for individuals with a history of cervical incompetence.

Definition: A substance in vaginal secretions that can indicate potential for labor r/t placental inflammation.
Procedure: Swabbing the vagina during the late second trimester/early third trimester.
Predictive Nature: While it indicates who is unlikely to go into labor, it should not be viewed as a guarantee.

Identification and Management of Risk Factors: Assessing lifestyle, prior history, and individual risk factors during history taking.
Hydration: Dehydration can induce contractions; mothers advised to hydrate and rest.
Education: Educating mothers about signs to watch for (e.g., low back pain, discharge, leaking fluid, vaginal bleeding, etc).

Tocolytics: Medications that suppress contractions, including:
- Magnesium Sulfate (Mag Sulfate/MgSo4): Fetal neuro protection of cerebral palsy; Smooth muscle relaxant, CNS depressant. Opposite of Calcium; anti-seizure. Kidney Function is important! Asses for magnesium toxicity per hospital policy (Q2).
- Terbutaline: A beta-adrenergic agonist; previously used extensively but with cardiovascular risks.
- Nifedipine: Calcium channel blocker that decreases the flow of calcium through the cell membrane (decreases smooth muscle contractile proteins); watch for blood pressure changes. DON’T GIVE WITH MgSo4, ERYTHROMYCIN, OR IMMEDIATELY AFTER TERBUTALINE, SUDDEN CARDIAC ARREST CAN OCCUR.
- Indomethacin: Blocks prostaglandins to reduce contractions, should be used short-term. Use with caution in patient with history of asthma and aspirin induced allergy.
- Goal: Use tocolytics to buy time for administering corticosteroids for fetal lung maturity and stimulate surfactant. Need good renal function to take these medications.
- Contraindications: Pre-E w/ severe features or Eclampsia; PPROM; Chorioamnionitis; Fetal Demise or lethal anomaly; non-reassuring fetal status; maternal bleeding w/ hemodynamic instability.

Betamethasone/Dexamethasone: Administered to promote fetal lung maturity; critical for babies under 34 weeks gestation.