In a study published February 24 in the American Journal of Obstetrics & Gynecology, researchers point out that the use of opioid painkillers like codeine and hydrocodone shortly before or during the first trimester of pregnancy more than doubled the chances of giving birth to a child with hypoplastic left heart syndrome and other defects like hydrocephaly, spina bifida and congenital glaucoma. Only 3% of the 4 million babies born annually in the United States have birth defects, but the majority of those defects are congenital heart defects, which can be caused by taking opioid pills.

The researchers of the study looked at the work of the National Birth Defects Prevention Study from which they dissected 17,449 interviews of mothers who had babies with birth defects in which they detailed the different medicines they took before and during their pregnancies and compared their results to interviews from 6,701 mothers who gave birth to perfectly healthy babies.

Although there is a definite link, the researchers wrote “the effects of opioid use on the developing fetus during pregnancy are poorly understood”, so exactly why the drugs cause these defects is not known. Dr. Cheryl S. Broussard from the National Center on Birth Defects and Developmental Disabilities said that even though the individual risk of giving birth to a defected baby for any one woman is relatively low, it is still a very serious issue and as many infant lives as possible need to be saved from the devastating effects of these pain medication-induced birth defects.