Although initially considered safe for the foetus, lithium has been shown to have teratogenic effects if used during the first trimester of pregnancy. Its use is also associated with a higher than expected frequency of still births and perinatal deaths. Our patient, in whom lithium prophylaxis was considered essential for clinical and social reasons, continued to take lithium without medical supervision throughout her pregnancy and had a still birth. We suggest avoiding the use of lithium at least during the first trimester of pregnancy.