Late Progesterone Also Cuts Repeat Preterm Births


MIAMI BEACH — Progesterone prevents recurrent preterm delivery to the same degree whether it is initiated earlier or later in the second trimester, according to a poster presentation at the annual meeting of the Society for Maternal-Fetal Medicine.

“We were thinking that those who started earlier would have some benefit. But essentially it doesn't matter if you start progesterone at 16–18 weeks or between 19 and 21 weeks,” said Dr. Gretchen Koontz of the ob.gyn. department at Wake Forest University in Winston-Salem, N.C.

In a 2003 study, researchers randomized women with a history of previous spontaneous preterm birth (before 37 weeks) to weekly injections of either 17 α-hydroxyprogesterone caproate (17P) or placebo (N. Engl. J. Med. 2003;348:2379–85). Of the 306 women who received 17P between 16 and 21 weeks' gestation, 36% delivered before 37 weeks, compared with 55% of the 153 women in the placebo group, a statistically significant difference.

As a secondary analysis of the original study data, Dr. Koontz compared 227 women who began weekly injections of 17P between 16 and 18 weeks, with 272 others who began 17P between weeks 19 and 21. Results showed that 36.5% of participants in the 16− to 18-week group delivered preterm, compared with 36.1% of those in the 19− to 21-week group.

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