According to two new studies, the use of prescribed opioid painkillers or a common class of antibiotics during pregnancy does not increase the risk of major birth defects in infants. These medications are often prescribed to pregnant women, and some previous studies had associated them with birth defects, but the findings from those studies were inconsistent.
The two new studies, published on February 10 in the British Medical Journal, aimed to clarify the issue and confirm or refute the results of earlier studies. In the first study, researchers led by Dr. Brian Bateman, an assistant professor of medicine at Brigham and Women's Hospital in Boston, analyzed data from over 82,000 American women who received two or more opioid medications during the first trimester of pregnancy between 2000 and 2015. The researchers found that after accounting for other potential risk factors, there was no clinically significant increase in the overall risk of major birth defects, or in the risk of heart defects, clubfoot, or neural tube defects in the infants born. Additionally, opioids were associated with an increased risk of cleft palate, affecting four to five cases per 10,000 pregnancies where opioids were used in the first trimester. The authors stated that doctors should inform patients about these potential risks before prescribing any opioid medications. According to Bateman and his research team, overall, the results suggest that the use of prescribed opioids in early pregnancy is not linked to a significant increase in the risk of major birth defects.
In the second study, researchers led by Dr. Niklas Worm Anderson from the Statens Serum Institut in Copenhagen analyzed data on nearly 1.2 million pregnancies in Denmark between 1997 and 2016. They found no association between the use of macrolide antibiotics in early pregnancy and the risk of infants being born with birth defects. Notably, macrolides are a class of antibiotics that includes azithromycin and erythromycin, but not penicillin. According to the study, the incidence rates of major birth defects were 35 cases per 1,000 pregnancies among women who used macrolides, compared to 37 cases per 1,000 among women who used penicillin, and 33 cases per 1,000 among women who did not use any antibiotics during pregnancy.
It is worth mentioning that both studies were observational, so they cannot prove causation. The research team noted that they relied on women taking medications prescribed by their attending physician. However, they added that these were large studies that used reliable data and considered a range of risk factors that may have influenced the results. The authors concluded that the findings should reassure women who are prescribed opioid painkillers or antibiotics during pregnancy.
