In a prospective study of anti-emetic drug use during 6 376 pregnancies, the previously demonstrated negative correlation between the use of such drugs and miscarriage was confirmed. It is probably completely due to less frequent and possibly less severe morning sickness complaints in pregnancies ending with a miscarriage. A slight positive correlation is found between the use of anti-emetics and infant malformation. A detailed analysis showed that this was mainly due to a high incidence of drug use (mainly promethazine) among women giving birth to infants with congenital dislocation of the hip. The probable indirect relationship is discussed.