Around one in seven pregnant women in the United States is prescribed a narcotic painkiller with documented risks of causing birth defects. According to the CDC, opioid painkillers including codeine, hydrocodone and oxycodone are linked to birth defects including incomplete development of the spinal cord (spina bifida), fluid buildup in the brain (hydrocephaly), and heart defects.

The FDA requires that they carry warning labels for pregnant women. Yet 14.4% of pregnant women in a recent large-scale study were prescribed one by their doctor, typically for common complaints like back pain and headache. Researchers from Harvard Medical School analyzed the medical and prescription histories of 534,500 women who had health and prescription insurance throughout their pregnancy.

Overall, 76,742 women (14.4%) were prescribed an opioid painkiller—30,566 of them (5.7%) during the first trimester when the risk to the fetus is highest. Prescriptions for opioids in the general population have skyrocketed in recent decades, with well over 200 million opioid prescriptions filled each year in the United States. The findings of this study should prompt more research from doctors, who don’t know if short-term opioid use during pregnancy is safe or not (although preliminary evidence suggests not) and, most importantly, more caution from pregnant women, who should not assume that their doctors know the safety profiles of the drugs they prescribe.

(Anesthesiology, 2014 Feb 12; doi: 10.1097/ALN.0000000000000172.)