Maternal lithium therapy and polyhydramnios.

Lithium is widely used in the treatment of bipolar affective disorders, and teratogenic effects include cardiovascular abnormalities, notably Ebstein anomaly. The most common side effect in the patient taking lithium is polyuria, a form of nephrogenic diabetes insipidus. We report the case of a manic-depressive gravida on lithium therapy who developed polyhydramnios in her last trimester. Because lithium crosses the placenta, we postulate that, by a similar mechanism, lithium may cause fetal polyuria which results in polyhydramnios.