ABSTRACT: The relationship of nausea during pregnancy with pregnancy outcome was studied using information from a post-pregnancy survey of a sample of women in a cohort of 7,767 pregnancies. Seventy-one percent of women were nauseated at some time during pregnancy. Nausea was unrelated to race and education. Younger women and those of higher parity were significantly (p < 0.05) more likely to be nauseated than older women and primiparas. The percentage of women nauseated during pregnancy was 70.1 in those who delivered a boy and 73.3 in those who delivered a girl, a difference that was not statistically significant (X2= 1.8, df 1, p = 18). The relative risks of spontaneous abortion and of ectopic pregnancy were significantly (p < 0.01) increased in women who were not nauseated at all during pregnancy, but there was no significant association of freedom from nausea with increased or decreased risk of stillbirth, congenital anomaly, or intrauterine growth retardation (IUGR). Twelve percent of women whose pregnancy lasted two or more trimesters had nausea throughout pregnancy. The relative risks of IUGR and of major and minor congenital anomaly were elevated in women with persistent nausea, although the elevations in risk were small and not statistically significant. Information about nausea of pregnancy may be useful in counseling pregnant women. It may help guide the evaluation of patients in whom ectopic pregnancy is a possibility, particularly where ultrasound is not available. If nausea is a biological marker for good placental function, better delineation of its physiologic basis might contribute to our understanding of variations in placental function and could result in development of a tool for monitoring it.