How hormone progesterone acts to prevent preterm birth

Washington, Feb 6 (ANI): Researchers at Yale School of Medicine may have uncovered the mechanism by which progesterone prevents preterm birth.

The findings will be presented at the Annual Scientific Meeting of the Society for Maternal-Fetal Medicine (SMFM) in Chicago by Errol Norwitz, M.D., professor in the Department of Obstetrics, Gynecology and Reproductive Sciences at Yale.

Preterm birth implies delivery prior to 37 weeks gestation. Premature infants are at least seven times more likely to die or have long-term neurologic injury compared with infants delivered at term.

Several recent studies have suggested that progesterone supplementation from weeks 16-20 of gestation through 36 weeks may prevent preterm birth in about one-third of high-risk women, but the molecular mechanism by which progesterone acts was not known until now.

One-third of preterm birth is linked to premature rupture of the fetal membranes. Prior studies have suggested that rupture results from weakening of the membranes by apoptosis (programmed cell death).

Norwitz and his Yale colleagues have shown for the first time that progesterone can prevent apoptosis in fetal membranes.

"We were able to demonstrate that progesterone prevents apoptosis in an artificial environment in the laboratory in which we stimulated healthy fetal membranes with pro-inflammatory mediators," said Norwitz. "Interestingly, and somewhat unexpectedly, we also saw an inhibition of apoptosis under basal conditions without the presence of pro-inflammatory mediators.

This suggests that the same mechanism may also be important for the normal onset of labor at term." (ANI)