Children's Health: Nitroglycerin Patch Shows Promise for Premature Labor
About 11 percent of American babies are born prematurely, which can cause breathing difficulties, learning disabilities, or even death. Yet the current therapies available often fail to halt early labor for more than a day or two, and little research exists to show whether they're effective at preventing health problems in infants. Now a recent finding published in the current issue of the American Journal of Obstetrics and Gynecology suggests that one such therapy, a nitroglycerin patch, might lead to better outcomes for babies, even though it doesn't appear to delay the onset of birth by more than a few days.
In the study, 153 women who were 24 to 32 weeks pregnant (full term is beyond 37 weeks) and having regular painful contractions were randomly assigned to be given either a nitroglycerin patch, approved for the treatment of chest pain in heart patients, or a placebo patch. Both groups also received steroid drugs to mature the baby's lungs. The researchers found that women treated with the nitroglycerin were about 70 percent less likely to give birth to babies who suffered lung disease, brain hemorrhage, or even death compared with those who were given placebos. Previous studies of other labor-halting drugs found no such beneficial effects. "The magnitude of the effect was greater than we expected," says study leader Graeme Smith, director of the perinatal research center at Queen's University Hospital in Kingston, Canada. "I suspect this will have a big effect in terms of hospitals offering this treatment to women in preterm labor," Smith says.
Nitroglycerin is frequently associated with headaches and, less commonly, low blood pressure. Smith speculates that during premature labor the drug works by relaxing the muscles of the uterus and increasing blood flow to the placenta. In current practice, most obstetricians use injections of the heart drug magnesium sulfate to help halt premature labor, according to Jay Iams, a professor of maternal-fetal medicine at Ohio State University College of Medicine in Columbus, who wrote an editorial on the study. But it, too, has side effects such as nausea and vomiting, and it hasn't been shown to improve birth outcomes. (The Food and Drug Administration has not approved any of the drugs for premature labor.) Given the study's small sample size, Iams says it's too soon to conclude that nitroglycerin is superior to the other drugs. He is conducting a larger multicenter trial comparing magnesium against a placebo. "Still, this new study has value," he says, "and should be used as a trigger for larger studies using the patch."