Using opioids during early pregnancy not linked to increased risk of congenital malformations, study finds

The use of prescription opioids during early pregnancy is not associated with an increased risk of most congenital malformations, although a small increase in risk of cleft palate is possible, a cohort study published in the BMJ has concluded (10 February 2021)​[1]​.  

The researchers, examining the risk of first trimester exposure to prescription opioids, carried out a population-based cohort study of more than 2.7 million pregnancies in the United States.  

Of these, more than 82,000 of the women were dispensed 2 or more prescriptions of any opioid during the first trimester. 

In their analysis of the data, the researchers found that pooled risk estimates did not suggest a substantially increased risk for congenital malformations overall (relative risk [RR] 1.06, 95% confidence intervals [CI] 1.02 to 1.10), cardiovascular malformations overall (RR 1.09, 95% CI 1.00 to 1.18) or other defects, such as ventricular or atrial septal defects, neural tube defects or club foot. 

In contrast, the pooled risk estimate for oral cleft remained high after adjustment (RR 1.21, 95% CI 0.98 to 1.50) which was attributable to an increase in the risk for cleft palate, the researchers said. The risk corresponded to 4–5 additional cases of cleft palate per 10,000 pregnancies exposed to opioids in the first trimester.  

The authors said clinicians should “counsel” patients about this risk.