By record linkage of a discharge diagnosis registry and a medical birth registry we identified 350 women with manic-depressive disease who had born a child. The total delivery outcome was poorer than expected with a high perinatal death rate and a high malformation rate. Further studies revealed a high rate of perinatal deaths and/or congenital malformations among infants born of women who had used drugs in early pregnancy, and this phenomenon was concentrated to women who had used lithium and to heart defects. The sample is small, however, and there is no statistically significant difference between delivery outcome in women on lithium and in women on other psychotropic drugs. Until better risk estimates are obtained, lithium should not be used in early pregnancy.