NEW YORK (Reuters Health) - Women who take opioid painkillers such as codeine and oxycodone early in their pregnancy may be more likely to have a baby with a birth defect, according to a new study.
The link was only seen for some kinds of birth defects, however, and the overall risk remains small.
About 3 percent of babies born in the U.S. have a malformation, including cleft palate, heart defects and spina bifida, in which the fetus's spinal column doesn't close properly.
Birth defects are the leading cause of death for infants. Smoking and drinking alcohol during pregnancy have been linked to an increased risk of having a baby with birth defects, but the cause of many birth defects is still unknown.
Whether opioid painkillers may be a contributing factor is still up for debate, and the new findings can't prove cause and effect.
"Previous studies have had some inconsistent findings, (but) some have suggested that opioids might increase the risk for heart defects and oral clefts," lead author of the new study Dr. Cheryl Broussard, of the Centers for Disease Control and Prevention in Atlanta, told Reuters Health.
The current study included data on more than 17,000 women in 10 different states who gave birth to a baby with a birth defect between 1997 and 2005.
As a comparison group, the authors included about 7,000 women who lived in the same regions and gave birth around the same time, but whose babies did not have any malformations.
During the 2 years after they gave birth, all women in the study were interviewed about what medications they had taken during pregnancy. The authors were particularly interested in what drugs women had taken in the month before they became pregnant and in their first trimester, which is the most important window for the healthy development of a fetus.
Of women who had babies without birth defects, 2 percent had taken an opioid -- including codeine, hydrocodone, and oxycodone. That number was 2.6 percent among women whose babies had a birth defect.
According to the findings, the drugs were linked to certain birth defects but not others. Mothers of babies born with spina bifida were twice as likely to have taken these medications as women whose babies didn't have a birth defect, for example.
Women whose babies had a heart defect were about 1.4 times more likely to have taken opioids shortly before their pregnancy and in their first trimester.
For some other birth defects, including cleft lip and cleft palate, there was no relationship to a mother's medication history. Broussard said that more research needs to be done to understand the connection between opioids and birth defects.
Women in the study most commonly reported taking the powerful painkillers following surgery, or when they had infections or chronic diseases.
The study, which is published in the American Journal of Obstetrics and Gynecology, does not prove that taking medications containing opioids increases the risk of having a baby with a birth defect.
Other procedures or drugs could have been involved in the link -- for example, women who took painkillers after surgery would also likely have had anesthesia, which could potentially be linked to birth defects itself, the authors say.
The findings also don't mean that women who are pregnant or thinking of becoming pregnant should avoid opioid medication at all costs -- just that they should be aware of the possible risks of the drugs.
Dr. David Haas, of the Indiana Institute for Personalized Medicine, said that in many cases the benefits of taking these medications might be more important than the potential risk.
"Yes, there may be a slight increased absolute risk (of some birth defects), but the overall risk is still low," Haas, who was not involved in the study, told Reuters Health. "These conditions are still very rare."
The most important thing, Haas said, is that women have a discussion with their doctor about the risks and benefits of taking these medications early in pregnancy when they have an underlying medical condition that calls for strong painkillers.
Broussard agreed. "When making medical treatment decisions either just before or during pregnancy, it's important that women talk with their doctors and weigh their options," she said.
SOURCE: http://bit.ly/fBRSZh American Journal of Obstetrics and Gynecology, online February 24, 2011.
