Women with a history of delivering their babies too soon may be able to prolong their pregnancy with a synthetic form of progesterone, according to a study published today in the New England Journal of Medicine.
A three-year, multi-center study that included four Utah hospitals found use of hydroxyprogesterone caproate, also called 17P, reduced preterm births by a third, said Dr. Michael Varner, professor of maternal-fetal medicine at the University of Utah medical school and principal investigator for the Utah part of the study, which included the U.'s Hospitals and Clinics, LDS Hospital, McKay-Dee Hospital and Utah Valley Regional Medical Center.
The results were so dramatic the study was stopped early, but how the hormone works is not completely clear, Varner said.
Preterm delivery is a huge problem, costly both in terms of health-care dollars and human misery. Varner said that more than $10 billion is spent each year on direct health care costs caused by it. And the cost for long-term disabilities goes much higher.
Forty years ago, 9 percent of all deliveries were premature, meaning before 37 weeks. That number has risen to 11 percent or one in nine births, Varner said. Delivery at 32 weeks or before is considered a "break point" for serious long-term consequences or death. Of babies born between 23 and 25 weeks gestation who survive, at age 5 half are healthy and have developed normally, one-fourth have mild to moderate impairments and one-fourth are severely impaired.
Oddly, though, surveys have found that "people in the United States don't see prematurity as a major problem," he said.
Study subjects had already had at least one preterm delivery and were 16 to 20 weeks pregnant. In random assignment, two-thirds received weekly shots of 17P and one-third a placebo. The mean gestational age for previous deliveries was 30 weeks. Not surprisingly, women who had delivered a baby only slightly early "weren't that interested in going in once a week to get a shot in their rear ends" for the sake of prolonging a pregnancy a week or two, he said. Most of the women had had at least one baby very early, with serious long-term problems or even infant death.
The difference was significant, with only 36.3 percent of the women taking the hormone delivering their babies before 37 weeks, while 54.9 percent of those on placebo delivered early.
Progesterone relaxes the smooth muscle walls of the uterus and blocks the hormone that makes the uterus contract. It also stops formation of connections that let uterine muscle cells talk to each other so they contract together.
According to the study, led by Dr. Paul J. Meis, professor of obstetrics and gynecology at Wake Forest University, the babies of women who received the 17P fared better overall, needing less help breathing and were less likely to have inflamed bowels than those in the placebo group.
Premature birth is blamed for the rise in infant mortality in the United States. And ethnicity makes a difference, with African-Americans more apt to deliver prematurely than whites. The study results were the same regardless of race.
It doesn't answer all the questions about risk, said Varner, who will urge "cautious utilization" because there have not been long-term studies of the effects of 17P use. He hopes, too, that doctors will learn to better identify women who are likely to deliver prematurely. He wants more study, though, "before we give it a wholesale endorsement as the new standard of care" for women with a history of preterm deliver.
But Varner calls the finding "exciting" and "hopeful."
Follow-up studies being planned include 17P's effectiveness in preventing preterm delivery for women expecting multiple babies, which usually deliver early, and if a suppository is as effective as an injection.
E-mail: lois@desnews.com