Objective: To study the effects of amniotic fluid obtained during early second trimester of normal human pregnancies on prostaglandin production in cultured myometrial and amniotic cells.
Study design: Cultured human myometrial and amniotic cells were incubated with human amniotic fluid obtained by amniocentesis and fractionated by ultrafiltration. Prostaglandin E2 was measured in the incubation media. In one case, amniotic fluid was obtained during the days following intra-uterine fetal death (IUFD).
Results: PGE2 production in myometrial and amniotic cells was significantly decreased when incubated with the fraction of amniotic fluid containing molecules of molecular weight between 3 and 30 kD. This inhibition was still present after heating. After IUFD, the inhibitory activity of amniotic fluid was persistent for the first 3 days but had disappeared 6 days after IUFD.
Conclusion: These data suggest that a factor contained in amniotic fluid, with a molecular weight within the 3- to 30-kD range, and possibly produced or controlled by the fetus, inhibits PG synthesis. Further work is necessary to characterize this factor and evaluate its physiological role in human parturition.