Suicide attempts by drug ingestion during pregnancy provides an opportunity to study the teratogenicity of large doses of drugs in human beings. Data of a population-based prospective study of all pregnant women admitted to the toxicological inpatient hospital in Budapest which is responsible for the health provision of chemical poisoned persons from a 3 million study population. Of 22,969 self-poisoned women, 645 were pregnant and 559 attempted suicide by drug ingestion during pregnancy during the study period (1985-1993). Two died. The peak of suicide attempts was found in the first month of fetal development, and its great majority resulted in a very early fetal death, the so-called chemical pregnancy. Thus 61% of suicide attempts occurred before the third month. Later pregnancies had a protective effect against suicide parallel with advanced months of fetal development.