A new study published by the Canadian Medical Association Journal (CMAJ) shows a small increased risk of congenital abnormalities in infants exposed to opioids in the first trimester of pregnancy.

The paper, authored by Queen’s researchers Dr. Susan Brogly (Department of Surgery) and Alexa Bowie (MPH 2021) and female scientists from Canadian and U.S. institutions, analyzed administrative health data from Ontario on almost 600,000 mother-infant pairs to determine the association between opioid pain medications in early pregnancy and congenital abnormalities in infants. The findings showed that two per cent of fetuses were exposed to prescribed opioid pain medications. These drugs can cross the placenta and have the potential to cause harm.

“This research confirms evidence of a small increased risk of birth defects from opioid analgesic exposure in the first trimester, and that this small increased risk is not due to other risk factors for fetal harm in women who may take these medications,” says Dr. Brogly.

According to the study, of the mother-infant pairs, two per cent of infants were exposed to opioid pain relief medicines such as codeine, oxycodone, hydromorphone, tramadol, morphine and others. The study found an increased risk, though low, of major anomalies with tramadol and morphine exposure, and minor anomalies with exposure to codeine, hydromorphone, and oxycodone. Observed specific congenital anomalies included gastrointestinal neoplasms and tumors, ankyloglossia, and genital anomalies.

This large study adds to earlier evidence from researchers in Sweden and Norway, and a recent study of pregnant U.S. Medicaid beneficiaries, which also suggested a small increased risk of congenital anomalies, an important finding for a pregnant person who may need to take opioids for pain relief.

“The research can benefit women who have pain in pregnancy or have pain and want to conceive to make informed choices regarding pain management. This provides needed data so physicians can counsel patients on the true risks of pain medications,” Dr. Brogly says.

“Pharmacists are well placed to educate expectant mothers; physicians too, though by the time a woman realizes she is pregnant and has a prenatal visit, exposure may have already occurred,” Dr. Brogly adds. “Organizations like the Society of Obstetricians and Gynecologists of Canada and March of Dimes have up-to-date and trustworthy information for women who are pregnant or want to become pregnant.”

Meaningful mentorship

This is the first author publication in CMAJ for Alexa Bowie, a graduate of Queen’s Public Health Sciences. Bowie worked on Dr. Brogly’s NIH-funded study for her practicum placement in summer 2020 and continued with the study team following completion of the practicum.

“Contributing to this important area of research as part of my practicum was an incredibly rewarding experience,” Bowie says. “Dr. Brogly is an extraordinary mentor whose dedication to supporting future researchers empowered me to grow as an epidemiologist.”

The paper, ‘Prescribed opioid analgesics in early pregnancy and the risk of congenital anomalies: a population-based cohort study’, is now available on the CMAJ website.