Pregnancy outcome following in utero exposure to lithium: a prospective, comparative, observational study

The authors conducted a prospective, comparative observational study to evaluate the risk of major anomalies following exposure to lithium during pregnancy.

A total of 183 lithium-exposed pregnancies of women who contacted the Israeli Teratology Information Service were followed up (90.2% in the first trimester) and compared with 72 disease-matched and 748 nonteratogenic-exposed pregnancies.

There were significantly more miscarriages (adjusted odds ratio=1.94, 95% CI=1.08-3.48) and elective terminations of pregnancy (17/183 [9.3%] compared with 15/748 [2.0%]) in the lithium-exposed group compared with the nonteratogenic exposure group. The rate of major congenital anomalies after exclusion of genetic or cytogenetic anomalies was not significantly different between the three groups (lithium-exposed in the first trimester: 8/123 [6.5%]; bipolar: 2/61 [3.3%]; nonteratogenic: 19/711 [2.7%]). Cardiovascular anomalies occurred more frequently in the lithium group exposed during the first trimester when compared with the nonteratogenic exposure group (5/123 [4.1%] compared with 4/711 [0.6%]) but not after excluding anomalies that spontaneously resolved (3/123 [2.4%] compared with 2/711 [0.3%]). Ebstein's anomaly was diagnosed in one lithium-exposed fetus and in two retrospective lithium cases that were not included because contact with the information service was made after the prenatal diagnosis by ultrasound. The rate of noncardiovascular anomalies was not significantly different between the groups. The rate of preterm deliveries was higher in the lithium group compared with the nonteratogenic exposure group (18/131 [13.7%] compared with 41/683 [6.0%]).

Lithium treatment in pregnancy is associated with a higher rate of cardiovascular anomalies. Women who are treated with lithium during organogenesis should undergo fetal echocardiography and level-2 ultrasound.