HealthDay News — Opioid use in early pregnancy is associated with a small increase in risk for cleft palate but no increase in risk for most major congenital malformations, and macrolide use in pregnancy is not associated with increased risk for major birth defects in offspring, according to two studies published online February 10 in The BMJ.

Brian T. Bateman, MD, from Brigham and Women’s Hospital in Boston, and colleagues examined the risks of first trimester exposure to prescription opioids for major congenital malformations. Data were included for 1,602,580 publicly insured (MAX) and 1,177,676 commercially insured (MarketScan) pregnant women, of whom 4.4 and 1.1%, respectively, had 2 or more dispensations of any opioid during the first trimester. The researchers found that the absolute risk of malformations was 41.0 vs 32.0 per 1000 pregnancies exposed to opioids vs unexposed in the MAX cohort and 42.6 vs 37.3 per 1000 in the MarketScan cohort. The pooled unadjusted relative risk estimates were increased for all outcomes, but were attenuated after adjustment (relative risk for malformations overall: 1.06; 95% confidence interval, 1.02 to 1.10).

Nicholas Worm Andersson, MD, from the University Hospital Bispebjerg and Frederiksberg in Copenhagen, Denmark, and colleagues examined the association between macrolide antibiotic use in pregnancy (13,019 pregnancies) and major birth defects. The researchers found that there were 35.1 infants born with major birth defects per 1000 pregnancies among women who had used macrolides during pregnancy, compared with 37.0 per 1000 pregnancies among women who had used penicillin (relative risk ratio, 0.95; 95% confidence interval, 0.84 to 1.08).

“We believe that our data provide reassurance about the risk of major birth defects when treatment with macrolide antibiotics is needed during pregnancy,” Andersson and colleagues write.

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Several authors from the Bateman study disclosed financial ties to the pharmaceutical industry.

Abstract/Full Text – Bateman

Abstract/Full Text – Andersson