Effect of advancing gestational age on the frequency of fetal ductal constriction in association with maternal indomethacin use.

Abstract

The objective of this study was to determine whether indomethacin is associated with an increased incidence of constriction of the human fetal ductus arteriosus with advancing gestational age. A retrospective analysis of fetal echocardiograms performed in 44 patients with premature labor or hydramnios treated with indomethacin (25 mg orally every 6 hours) was undertaken. Fisher's exact test, Kaplan-Meier survival analysis, and log-rank techniques were used; a value of p < 0.05 was considered statistically significant. The frequency of ductal constriction was similar for fetuses of singleton and multiple gestations. A dramatic increase in constriction was noted at 32 weeks' gestation when the rate of compromise approached 50%. The use of indomethacin should be restricted to gestational ages of < 32 weeks. In multiple gestations each fetus should be evaluated by echocardiography, because the ductal response may vary between individual fetuses.