Hormone use mixed in preventing premature births

BOSTON (Reuters) - Treatment with the female hormone progesterone cuts the risk of a premature birth in a woman with a truncated cervix, but does not prevent premature delivery if the mother is carrying twins, researchers said on Wednesday.

March of Dimes spokesman Michael Katz said the findings, contained in separate studies published in the New England Journal of Medicine, should give doctors a better idea of which women are likely to benefit from progesterone treatment.

Doctors have known for years that giving the hormone to women who have had one premature baby often prevents delivery of another. But 90 percent of premature babies, or "premies," are born to women have not had one previously

Researchers at eight hospitals tested the treatment on women known to have a cervix that is 15 mm or less -- which is less than half the average length -- because they are also at risk for delivering a child before 37 weeks of pregnancy.

Of the 125 receiving progesterone suppositories, 19 percent delivered a premature baby, compared to 34 percent of an equal number of women getting placebo capsules.

The risk of having a baby born with problems was 41 percent lower in the progesterone group, but the actual numbers were too small to be statistically significant.

The research team, led by Eduardo Fonseca of King's College Hospital in London, also found that only about 15 out of every 1,000 pregnant women had a short cervix.

"The findings of our study provide support for a strategy of routine screening of pregnant women by ultrasonographic measurement of cervical length and the prophylactic administration of progesterone to those with a short cervix," the researchers said.

In the study of twins, a team lead by Dwight Rouse of the University of Alabama at Birmingham found that weekly injections of progesterone didn't prevent miscarriage or babies from being born prematurely.

The rate was 41.5 percent among the 325 women who got the hormone shots versus 37.3 percent in the 330 who got placebo, an insignificant difference.

Twins now account for about 3.2 percent of births, up from 1.9 percent in 1980. Much of the increase is due to fertility treatments.

In a Journal editorial, Jim Thornton of Britain's University of Nottingham warned, "Even if progesterone therapy is effective for some women who are at risk of preterm labor, reliable evidence is needed about long-term effects on the children before it could be widely recommended."