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Hormone Treatment May Drastically Reduce Preterm Births

Huge Drop Seen in Women Given Progesterone
WebMD Health News
Reviewed by Laura J. Martin, MD

Dec. 14, 2011 -- A new finding may help many of the millions of women around the world at risk for premature birth.

The hormone progesterone, when given vaginally, reduced preterm birth by 42% in women at risk of premature delivery due to a short cervix, a new analysis shows.

The cervix is the lower portion of the uterus. Typically the cervix shortens toward the end of pregnancy when the body prepares for birth.

"Vaginal progesterone in women with a short cervix reduced both early and later preterm birth," says researcher Roberto Romero, MD, chief of the perinatal research branch of the National Institute of Child Health and Human Development.

Preterm birth is defined as delivery at less than 37 weeks. It is on the rise in the U.S. It increased from more than 9% of births in 1981 to more than 12% in 2006 -- now about 1 in 8 babies. It's linked to potential health problems for the baby. A full-term pregnancy is about 40 weeks.

The treatment had a number of other benefits, Romero tells WebMD. It reduced the rate of breathing problems and the need for mechanical ventilation in the infants. Babies were less likely to need intensive care.

Based on the new analysis, Romero and his team suggest that all pregnant women should have their cervix measured between 19 to 24 weeks of pregnancy. If the cervix is shortened, the treatment should be considered.

The new analysis is published online in the American Journal of Obstetrics and Gynecology.

Progesterone to Prevent Preterm Birth

Progesterone is a crucial hormone for maintaining pregnancy. If progesterone declines, it can lead to shortening of the cervix. This can raise the risk of preterm delivery.

Romero and his team looked at the results of five previously published studies. Each compared vaginal progesterone to a placebo. Vaginal progesterone comes in several forms, such as a capsule, gel, or suppository.

The studies included 775 women and 827 infants.

The 42% reduced risk was for birth before 33 weeks. The progesterone also reduced the risk of birth before 28, 32, and 35 weeks.

"Early preterm birth is less common, but those babies have many complications," Romero tells WebMD.

Progesterone treatment also reduced the risk of breathing problems by about 52% and the need for mechanical ventilation by 34%. Fewer babies whose mothers got the progesterone had to be admitted to neonatal intensive care units.

The progesterone also helped those women who had had a previous preterm birth and a short cervix, the researchers found.

FDA to Consider Progesterone Treatment

If an ultrasound taken at 19 to 24 weeks shows a shortened cervix, the researchers say, doctors should consider recommending a 90-milligram-a-day dose of vaginal progesterone starting at about 20 weeks.

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