Progesterone Shots May Not Prevent Preterm Birth of Twins: Study

What works for singletons doesn't necessarily work for multiples, researchers find.

THURSDAY, Feb. 14 (HealthDay News) -- Progesterone shots are not effective in preventing preterm delivery of twins, say French researchers, who found that the hormone injections could actually do more harm than good.

The researchers were working with a form of progesterone called 17P. "We found that 17P was not effective in women with twin pregnancies and a short cervix (defined as less than 25 millimeters between 24 and 32 weeks)," study co-author Dr. Philippe Deruelle of the Hospital Jeanne de Flandre, Lille 2 University, in France, said in a news release from the March of Dimes.

"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," Deruelle said.

The study involved 161 women older than 18 treated at 10 university hospitals between June 2006 and January 2010. The researchers noted 17P has been shown to prevent premature delivery in about one-third of women pregnant with one child who had a previous preterm delivery.

According to a March of Dimes spokesman, 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," Dr. Edward McCabe, March of Dimes senior vice president and medical director, noted in the news release. "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."

To assess their risk for premature delivery, the study's authors advised women pregnant with twins to undergo an ultrasound to measure their cervical length.

The study was scheduled for presentation Thursday at the Society for Maternal-Fetal Medicine's annual meeting in San Francisco.

Data and conclusions presented at meeting are typically considered preliminary until published in a peer-reviewed medical journal.

More information

The U.S. National Institutes of Health provides more information on progesterone.