How to manage previable preterm labor?

From the Guidelines

Managing previable preterm labor (before 24 weeks gestation) requires careful consideration of risks and benefits, as interventions may not improve neonatal outcomes, and the most recent guidelines from the Society for Maternal-Fetal Medicine recommend individualized counseling and management based on gestational age, maternal condition, and informed patient preferences 1.

Initial Assessment and Management

The initial approach should include thorough assessment with physical examination, cervical evaluation, and fetal monitoring.

• For tocolysis, first-line medications include nifedipine (10-20mg orally every 4-6 hours) or indomethacin (50-100mg loading dose, then 25-50mg every 6 hours for up to 48 hours) 1.
• Magnesium sulfate (4-6g IV loading dose, then 1-2g/hour) may be used for neuroprotection if approaching viability.
• Antenatal corticosteroids (betamethasone 12mg IM, two doses 24 hours apart, or dexamethasone 6mg IM, four doses 12 hours apart) should be considered if approaching viability (22-23 weeks) 1.
• Antibiotics are indicated only for confirmed infections.

Patient Counseling and Decision-Making

Patient counseling is crucial, discussing the poor prognosis before viability, potential maternal risks of intervention, and involving neonatology if approaching viability.

• Management decisions should be individualized based on gestational age, maternal condition, and informed patient preferences, recognizing that aggressive interventions may not be beneficial before viability and could expose the mother to unnecessary risks 1.
• Pregnant individuals with previable and periviable preterm prelabor rupture of membranes should receive individualized counseling about the maternal and fetal risks and benefits of both abortion care and expectant management to guide an informed decision 1.

Transfer and Referral

Whenever possible, periviable births for which maternal or neonatal intervention is planned should occur in centers that offer expertise in maternal and neonatal care and the needed infrastructure, including intensive care units, to support such services 1.

• Efforts should be made to transfer women before delivery, if feasible, because antenatal transfer has been associated with improved neonatal outcome when compared with transport of a neonate after delivery 1.

From the FDA Drug Label

Continuous administration of magnesium sulfate is an unapproved treatment for preterm labor The safety and efficacy of such use have not been established. The administration of magnesium sulfate outside of its approved indication in pregnant women should be by trained obstetrical personnel in a hospital setting with appropriate obstetrical care facilities

The management of previable preterm labor is not explicitly addressed in the provided drug labels.

• Key points:
  • Magnesium sulfate is not approved for the treatment of preterm labor.
  • The safety and efficacy of magnesium sulfate for this use have not been established.
  • Administration of magnesium sulfate for preterm labor should only be done by trained obstetrical personnel in a hospital setting. Given the lack of direct information on managing previable preterm labor, no conclusion can be drawn from the provided drug labels 2 2.

From the Research

Management of Previable Preterm Labor

The management of previable preterm labor involves several strategies to delay delivery and improve neonatal outcomes. Some key considerations include:

• Tocolysis to delay delivery for at least 48 hours, allowing for transfer to a tertiary facility and administration of corticosteroids to induce surfactant production in fetal lungs 3
• Use of antenatal corticosteroids to prevent neonatal morbidity and mortality associated with preterm birth, including respiratory distress syndrome, intraventricular hemorrhage, necrotizing enterocolitis, and death 4
• Administration of corticosteroids from 24 to 34 weeks of gestation to hasten fetal lung development, with repeated courses potentially improving neonatal outcomes compared to a single course 5

Tocolytic Agents

Several tocolytic agents are available, including:

• Nifedipine, a calcium channel blocker that has superior tocolytic properties and better neonatal outcomes compared to betamimetics 3, 6
• Atosiban, an oxytocin receptor antagonist with a favorable maternal safety profile, but limited evidence of effectiveness in reducing perinatal mortality and morbidity 3, 6, 7
• Magnesium sulfate, which is not recommended as a tocolytic agent due to lack of evidence of effectiveness, but may be valuable as a neuroprotective agent and for treatment of eclamptic seizures 3, 6

Treatment Considerations

When managing previable preterm labor, the following treatment considerations should be taken into account:

• The goal of tocolysis is to delay delivery for at least 48 hours, allowing for transfer to a tertiary facility and administration of corticosteroids 3
• Repeated courses of prenatal corticosteroids may improve neonatal outcomes compared to a single course, but further study is needed to determine the optimal treatment strategy 5
• The choice of tocolytic agent should be based on the individual patient's needs and medical history, with consideration of the potential benefits and risks of each agent 7