Tocolysis with indomethacin increases the incidence of necrotizing enterocolitis in the low-birth-weight neonate.

OBJECTIVE: The null hypothesis states that prolonged antenatal indomethacin exposure within 24 hours of delivery does not increase the incidence of necrotizing enterocolitis in the low-birth-weight neonate.

STUDY DESIGN: The neonates of patients receiving indomethacin tocolysis admitted in preterm labor (N = 56) were compared with the neonates of preterm labor patients who received no indomethacin tocolysis (N = 703). These neonatal groups were then compared with regard to gestational age at delivery, birth weight, mode of delivery, antenatal magnesium and steroid exposure, incidence of respiratory distress syndrome, perinatal depression, sepsis, umbilical catheterization, and feeding rates and volumes. The overall incidence of necrotizing enterocolitis, mortality secondary to necrotizing enterocolitis, and the intervals from delivery and feeding to necrotizing enterocolitis diagnosis were also compared. The association between necrotizing enterocolitis and the duration of indomethacin exposure and the interval from exposure to delivery for both the indomethacin and control groups was determined.

RESULTS: The incidence of necrotizing enterocolitis in neonates who were delivered within 24 hours of maternal indomethacin therapy was 20% compared with 9% in the control group (p = 0.005). The incidence of necrotizing enterocolitis in neonates with > 48 hours of antenatal indomethacin exposure was 26.4% compared with 4.1% in those with < 48 hours exposure (p = 0.042). The interval from first feeding to necrotizing enterocolitis development was significantly shorter in the indomethacin group versus the control group (2.1 +/- 3.0 vs 6.8 +/- 6.3 days) (p = 0.001), as was the mean interval from delivery to development of necrotizing enterocolitis (10.2 +/- 3.7 vs 15.2 +/- 3.8 days) (p = 0.019).

CONCLUSIONS: Antenatal indomethacin exposure occurring within < or = 24 hours of delivery and of at least 48 hours' duration is associated with a significant increase in the incidence of necrotizing enterocolitis in the low-birth-weight neonate.