EFFECT OF ADVANCING GESTATIONAL-AGE ON THE FREQUENCY OF FETAL DUCTAL CONSTRICTION IN ASSOCIATION WITH MATERNAL INDOMETHACIN USE

OBJECTIVE: 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. STUDY DESIGN: 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. RESULTS: 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%. CONCLUSIONS: 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.