Study shows progesterone shots do not reduce preterm delivery in twin pregnancies

In a study to be presented on February 14 between 8 a.m. and 10 a.m. PST, at the Society for Maternal-Fetal Medicine's 33rd annual meeting, The Pregnancy Meeting ™, researchers will report findings that suggest that 17P, a form of progesterone, is not effective in preventing preterm birth among women with twin pregnancies—and may possibly be harmful.

While 17P (17 alpha-hydroxyprogesterone caproate) has been shown to prevent premature delivery among about one-third of women with a singleton pregnancy who have experienced a prior preterm delivery, this latest research shows that 17P prescriptions can't do the same for moms having twins, the authors say.

"We found that 17P was not effective in women with twin pregnancies and a short cervix (defined as less than 25 mm between 24 and 32 weeks)," says Philippe Deruelle, MD, with the Department of Obstetrics and Gynecology at Hôpital Jeanne de Flandre, Université Lille 2, France, and one of the study's authors. "We actually seemed to have found an increase in the rate of preterm delivery before 32 weeks in the treatment group when compared to the non-treatment group."

For the study reported in the abstract, entitled: Prevention of preterm delivery by 17 alpha-hydroxyprogesterone caproate in asymptomatic twin pregnancies with a short cervix: a randomized controlled trial, Deruelle and his colleagues conducted their trial on 165 women over the age of 18 at 10 university hospitals between June 2006 and January 2010. Outcome data was available for 161 of the 165 (97.6%) women.

"Twins are very high risk for preterm delivery, in fact, 60 percent of twins are born too soon. We can't assume that what works for singleton pregnancies will work with multiples such as twins or triplets," says Edward R. B. McCabe, MD, PhD, March of Dimes senior vice president and medical director. "This research finding is valuable because it will guide the care of women with a multi-fetal pregnancy, and highlights the need to better understand how to prevent preterm births for multiples."

Dr. Deruelle recommends that women who know they are pregnant with twins get an ultrasound to measure their cervical length, as this factor has shown to predict which women with twins are at higher risk for premature pregnancy.

Dr. McCabe will present Dr. Deruelle with the March of Dimes award for Best Abstract in Prematurity at the SMFM's Annual Meeting. 2013 marks the 10th year the March of Dimes award has been presented.