To assess whether first-trimester exposure to pregabalin is associated with an increased risk of major congenital malformations, as recently suggested in a pregnancy registry study.

We performed a cohort study nested in the US Medicaid Analytic eXtract (MAX). The study population included 1,323,432 pregnancies resulting in a live-born infant between 2000 and 2010. We examined the risk of major congenital malformations among infants born to women exposed to pregabalin during the first trimester compared with women unexposed to anticonvulsants. We used propensity score fine stratification to control for >50 potential confounders, and we estimated relative risks (RRs) and 95% confidence intervals (CIs) in generalized linear models. The analyses were replicated in the Truven Health MarketScan Commercial Database (MarketScan). Pooled estimates based on the adjusted RR produced in MAX, MarketScan, and the previous registry study were calculated.

Of 477 infants exposed to pregabalin during the first trimester in MAX, 28 (5.9%) had malformations compared to 3.3% in nonexposed infants. The crude RR of major congenital malformations for pregabalin was 1.80 (95% CI 1.26–2.58). After propensity score adjustment, the RR moved to 1.16 (95% CI 0.81–1.67). Restriction to pregabalin monotherapy and sensitivity analyses produced similar results. The adjusted RR for major congenital malformations for the 174 infants exposed in MarketScan was 1.03 (95% CI 0.56–1.90). The pooled RR was 1.33 (95% CI 0.83–2.15) for pregabalin any use and 1.02 (95% CI 0.69–1.51) for pregabalin monotherapy.

Findings did not confirm the suggested teratogenic effects of pregabalin, although they cannot rule out the possibility of a small effect.