In some countries, including Sweden, no risk is considered to exist with the use of meclozine for nausea and vomiting in pregnancy (NVP), but in other countries warnings against use during pregnancy are given. Rat tests indicate a teratogenic risk and published epidemiological studies are of restricted size. Delivery outcome was studied in 16,536 women who reported the use of meclozine in early pregnancy and was compared with all 540,660 women who gave birth. Information on drug usage was obtained prospectively in early pregnancy. Risk factors for using meclozine were young maternal age, to have had a previous child, not to smoke, to have a low body mass index. The use of some other drugs (antihypertensives, thyroxine, anticonvulsants) decreased the use of meclozine. Maternal diagnoses of preeclampsia or diabetes were less frequent when the woman had used meclozine. The twinning rate was increased and the sex distribution of the infants low (female excess). Preterm birth, low birth weight, short body length, and small head circumference occurred at a reduced rate after meclozine use, notably for boys. Also the rate of congenital malformations was reduced. If anything, delivery outcome is better than expected when the mother used meclozine. These beneficial effects are probably secondary to NVP. Meclozine can apparently be used without risk at this condition.