Mechanism that prevents preterm birth by way of progesterone may have been uncovered

A group of researchers at Yale School of Medicine may have discovered how preterm birth can be prevented with the help of progesterone hormone.

Over the past 40 years preterm birth rates have increased considerably. As many as one in every eight pregnancies results in a delivery before 37 weeks of gestation. Preterm birth babies are about seven times more prone to dying, having neurologic injuries and have a higher risk of general health issues.

Although efforts to prevent preterm births have been unsuccessful, recent studies show that supplementing progesterone in weeks 16 or 20 through week 36 of gestation could prevent preterm birth in over 30 percent of high risk women. The mechanism that is molecularly responsible for this finding was previously unknown.

But Yale researchers have recently been able to discover the role progesterone plays in preventing premature births. About a third of preterm births are linked to the fetal membrane rupturing prematurely. Earlier studies proposed that the rupturing was caused by membrane weakening from apostosis (a programmed cell death).

Errol Norwitz, M.D., professor in the Department of Obstetrics, Gynecology & Reproductive Sciences at Yale, along with his colleagues, have been able to show that progesterone is capable of preventing apostosis 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. They were also able to unexpectedly see how apostosis was inhibited without there being pro-inflammatory mediators under basal conditions, which suggests the same mechanism could also play a role on the normal onset of labor at term, he added.

The findings of this study will be presented at Annual Scientific Meeting of the Society for Maternal-Fetal Medicine (SMFM) in Chicago.