In one trial of 1062 women, magnesium sulfate or placebo was given at 30 weeks’ gestation. Two years following birth, children of mothers who received magnesium sulfate exhibited less gross motor dysfunction than those born to mothers who received placebo, 18% vs 34% respectively (LOE: 1).42 However, the rate of pediatric mortality and cerebral palsy, the primary endpoints of the study, did not differ between the groups. Further studies are necessary before magnesium sulfate can be recommended for neuroprotection.
Prostaglandin inhibitors may be preferred for hydramnios
Indomethacin is the prostaglandin synthetase inhibitor most studied in preterm labor, though the numbers of patients in these studies was generally small.33 Indomethacin reduced the rate of preterm delivery within 7 days of treatment and before 37 weeks gestation. However, it did not decrease the rate of neonatal morbidity. Importantly, indomethacin was associated with an increased risk of postpartum hemorrhage (LOE: 1).33 A retrospective review demonstrated an increase in incidence and severity of postnatal patent ductus arteriosus in neonates whose mothers were treated with indomethacin (LOE: 2).43 Most prospective studies, however, have not found this complication. Prostaglandin inhibitors may be the preferred choice of tocolytics if hydramnios is suspected in conjunction with preterm labor.
Antibiotics: one indication only
It is hypothesized that women who experience preterm labor have infections of the upper genital tract, and that infection or inflammation leads to contractions. A meta-analysis of 11 randomized trials with 7428 women in preterm labor and intact membranes demonstrated that, although prophylactic antibiotics decreased the incidence of maternal infection, there was no benefit in neonatal outcomes (LOE: 1).44 Although it did not reach statistical significance, there was a trend towards an increase in neonatal deaths in the antibiotic group, raising concerns about their use. Therefore, administration of prophylactic antibiotics in this patient population is not recommended. Conversely, antibiotic prophylaxis is recommended for all women colonized with group B streptococcus, unless a cesarean delivery is planned, to prevent perinatal disease.45
Corticosteroids beneficial for preterm infants
Antenatal corticosteroids reduce mortality, incidence and severity of respiratory distress syndrome, and intraventricular hemorrhage in preterm infants (LOE: 1).46 Women at risk for preterm delivery between 24 and 34 weeks of gestation should be given betamethasone 12 mg IM, two doses 24 hours apart, or dexamethasone 6 mg IM, two doses 12 hours apart. There are no significant maternal or neonatal adverse effects with these regimens. Administration of tocolytic drugs may be necessary to prolong gestation and provide time for steroids to act.
Corresponding author Adrienne Z. Ables, PharmD, Spartanburg Family Medicine Residency Program, 853 N Church St Suite 510, Spartanburg, SC 29303. E-mail: azables@srhs.com.
