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Slight increased risk of congenital abnormalities in infants exposed to opioid medications in utero

February 7, 2022 Kingston

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

The study analyzed administrative health data from Ontario on almost 600 000 birth parent–infant pairs to determine the association between opioid pain medications in early pregnancy and congenital abnormalities in infants. Prescribed opioid pain medications can cross the placenta and have the potential to cause harm, and about 2%–4% of fetuses are exposed to these drugs.

Among the infants included in the study, 2% (11 903) were exposed in utero to opioid analgesics, such as codeine, oxycodone, hydromorphone, tramadol, and morphine. The study found an increased risk, albeit low, of major anomalies with exposure to tramadol and morphine, and minor anomalies with exposure to codeine, hydromorphone and oxycodone. Specific congenital anomalies observed included gastrointestinal and genital anomalies, neoplasms and tumours, and ankyloglossia.

This large study adds to earlier evidence from studies conducted in Sweden and Norway and from a recent study of pregnant US Medicaid beneficiaries that suggested a small increased risk of congenital anomalies, an important finding for a pregnant person who may be prescribed opioids for pain relief.

“Both the potential for harm or distress to the pregnant person as a consequence of foregoing treatment and the subsequent risk to the infant must be considered for effective treatment,” writes Dr. Susan Brogly, an epidemiologist and associate professor at Queen’s University, Kingston, Ontario, with coauthors. “These findings further quantify harms associated with prenatal exposure to opioid analgesics to inform treatment choices for pain in pregnancy.”

“Prescribed opioid analgesics in early pregnancy and the risk of congenital anomalies: a population-based cohort study” is published February 7, 2022.

About ICES
ICES is an independent, non-profit research institute that uses population-based health information to produce knowledge on a broad range of health care issues. Our unbiased evidence provides measures of health system performance, a clearer understanding of the shifting health care needs of Ontarians, and a stimulus for discussion of practical solutions to optimize scarce resources. ICES knowledge is highly regarded in Canada and abroad, and is widely used by government, hospitals, planners, and practitioners to make decisions about care delivery and to develop policy. In October 2018, the institute formerly known as the Institute for Clinical Evaluative Sciences formally adopted the initialism ICES as its official name. For the latest ICES news, follow us on Twitter: @ICESOntario

Media contacts

Julie Brown
Media Relations
Queen’s University
julie.brown@queensu.ca

Niveen Saleh
Director, Communications
ICES
niveen.saleh@ices.on.ca

General media contact

Kim Barnhardt
CMAJ
kim.barnhardt@cmaj.ca


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