Reproductive · Year 2 · from Reproductive
Case 2: Management of Preterm Labor with Tocolytics and Antenatal Corticosteroids
Clinical Image
Source: Wikipedia - Nifedipine - CC BY-SA 4.0
Case Presentation
A 29-year-old G1P0 at 28 weeks gestation presents with regular, painful uterine contractions every 4 minutes for the past 3 hours. She denies rupture of membranes, vaginal bleeding, or fever. Cervical examination reveals 3 cm dilation and 70% effacement. Fetal heart rate tracing is reassuring. Fetal fibronectin test is positive. The diagnosis is preterm labor at 28 weeks. The patient is admitted for tocolysis and antenatal corticosteroid administration. Nifedipine (calcium channel blocker) is chosen as the tocolytic agent, given as a loading dose of 20 mg orally followed by 10-20 mg every 4-6 hours. Nifedipine is preferred for its efficacy and favorable maternal side effect profile compared to beta-agonists. Betamethasone 12 mg IM is administered, with a second dose to be given in 24 hours to promote fetal lung maturity and reduce neonatal respiratory distress syndrome, intraventricular hemorrhage, and necrotizing enterocolitis. Magnesium sulfate 4 g IV bolus followed by 1-2 g/hour is also started for fetal neuroprotection to reduce the risk of cerebral palsy. Over the next 24 hours, contractions decrease significantly with nifedipine, and cervical change arrests. She receives both doses of betamethasone. Tocolysis is discontinued after 48 hours. She is discharged on activity restriction and progesterone supplementation. She goes on to deliver at 36 weeks following spontaneous labor.
Key Learning Points
- Tocolytic agents (nifedipine, indomethacin, magnesium sulfate, terbutaline) are used to delay delivery for 48 hours to allow administration of antenatal corticosteroids, not to prevent preterm birth long-term
- Nifedipine (calcium channel blocker) is often considered first-line tocolytic due to efficacy and favorable side effect profile; indomethacin is limited to <32 weeks due to risk of premature ductus arteriosus closure
- Antenatal corticosteroids (betamethasone or dexamethasone) significantly reduce neonatal morbidity and mortality when given between 24-34 weeks gestation
- Magnesium sulfate is given for fetal neuroprotection at <32 weeks; its antidote for toxicity is calcium gluconate