Yale scientists study preterm birth

NEW HAVEN, Conn., Feb. 9 (UPI) -- Yale University School of Medicine researchers say they may have discovered how the hormone progesterone functions to prevent preterm birth.

Preterm birth -- delivery prior to 37 weeks gestation -- has become increasingly common during the past 40 years, researchers said, but such premature infants are at least seven times more likely to die or have long-term neurologic injury compared with infants delivered at term.

Efforts to prevent preterm birth have been largely unsuccessful, but some studies have suggested progesterone supplementation from weeks 16-20 of gestation through 36 weeks might prevent some preterm births. But the molecular mechanism by which progesterone acts has not been known.

The Yale study shows, for the first time, progesterone can prevent premature rupturing of the fetal membranes that occurs from a weakening of the membranes by apoptosis -- programmed cell death.

"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 Professor Errol Norwitz, who led the study. "Interestingly, and somewhat unexpectedly, we also saw an inhibition of apoptosis under basal conditions without the presence of pro-inflammatory mediators. This suggests the same mechanism may also be important for the normal onset of labor at term."

The findings were presented in Chicago last week during a meeting of the Society for Maternal-Fetal Medicine.