Prostaglandins in the fetal circulation following maternal ingestion of a prostaglandin synthetase inhibitor during mid-pregnancy.

To assess the possible effect upon the fetus of maternal ingestion of the prostaglandin synthetase inhibitor, mefenamic acid, taken during mid-pregnancy (15-22 weeks) to prevent spontaneous abortion, samples of fetal blood were collected at fetoscopy from 13 treated and 14 untreated control cases. Mefenamic acid levels in the fetus were 32-54% of those in the mothers in the treated group, while prostaglandins E2 (PGE2), 6-oxo-PGF1 alpha and PGFM were all slightly but not significantly lower in those patients given 500 mg mefenamic acid 40-180 min prior to sampling than in untreated controls. Results indicate that the prostaglandin synthetase inhibitor crosses the placenta at this early gestation and may possibly suppress fetal prostaglandin production.