LACK OF EFFECT OF ANTENATAL INDOMETHACIN ON FETAL CEREBRAL BLOOD-FLOW

OBJECTIVE: Our purpose was to investigate fetal cerebral blood flow an d the incidence of intraventricular hemorrhage in patients undergoing tocolysis with either indomethacin or magnesium sulfate at <30 weeks' gestation. STUDY DESIGN: Consenting patients at <30 weeks' gestation w ith preterm labor were randomized to receive indomethacin or magnesium sulfate tocolysis. Magnesium sulfate was administered intravenously w ith an 8 gm loading dose given over the first hour, 4 gm over the seco nd hour, and then a maintenance infusion of 2.5 gm per hour. The infus ion was continued for approximately 12 hours after the cessation of ut erine contractions. Patients randomized-to receive indomethacin were g iven an initial dose of 50 to 100 mg orally or per rectum, followed by 25 to 50 mg orally every 4 to 6 hours for 24 to 48 hours. Oral tocoly tic agents were not used after successful tocolysis. Betamethasone was administered to all patients. Patients underwent fetal cerebral Doppl er studies during tocolytic therapy and at least 24 hours after comple tion of the treatment. RESULTS: Twelve patients were randomized to rec eive indomethacin and twelve patients were randomized to receive magne sium sulfate. Twenty-one fetuses underwent cerebral Doppler studies in triplicate during and after therapy. The mean gestational age at toco lysis was 27.5 +/- 1.9 weeks for the indomethacin group and 26.4 +/- 1 .6 weeks for the magnesium sulfate group (p = 0.14). The middle cerebr al artery resistance index for fetuses during indomethacin treatment w as 0.73 +/- 0.09, whereas the resistance index after therapy was 0.75 +/- 0.05 (p = 0.49). The resistance index during magnesium sulfate toc olysis was 0.79 +/- 0.04 and after therapy it was 0.76 +/- 0.04 (p = 0 .18). There was no significant difference in the resistance index betw een the groups on or off therapy. In addition, the incidence of intrav entricular hemorrhage was similar in both groups. CONCLUSION: These re sults suggest that indomethacin does not significantly affect fetal ce rebral blood flow. If antenatal indomethacin in the preterm fetus incr eases the risk of intraventricular hemorrhage, it would appear to be b y another mechanism.