During the first trimester, maternal use of lithium was associated with an increased risk of cardiac malformations, including Ebstein’s anomaly, although the magnitude of this effect was smaller than previously suggested, a recent study found. The cohort study included 1,325,563 pregnancies in women who were enrolled in Medicaid and who delivered a live-born infant between 2000 and 2010. Risk of cardiac malformations among infants exposed to lithium during the first trimester as compared with unexposed infants was examined, as was infants exposed to lamotrigine. Researchers found:
- Cardiac malformations were present in 16 of the 663 (2.41%) infants exposed to lithium, in 15,251 of the 1,322,955 (1.15%) nonexposed infants, and in 27 of the 1,945 (1.39%) infants exposed to lamotrigine.
- The adjusted risk ratio for cardiac malformations among infants exposed to lithium vs unexposed was 1.65.
- The risk ratio was 1.11 for a daily dose of ≤600 mg, 1.60 for 601 to 900 mg, and 3.22 for >900 mg.
- The prevalence of right ventricular outflow tract obstruction defects was 0.60% among lithium-exposed infants vs 0.18% among unexposed.
Patorno E, Huybrechts KF, Bateman BT, et al. Lithium use in pregnancy and the risk of cardiac malformations. N Engl J Med. 2017;376:2245-2254. doi:10.1056/NEJMoa1612222.