Epidemiology of vomiting in early pregnancy

Factors associated with early pregnancy vomiting were investigated in 9098 first-trimester registrants in the Collaborative Perinatal Project. Vomiting in the absence of hyperemesis or gastroenteritis was noted in 56% of all women, and was more common among primigravidas (P=.002), younger women (P<.001), women with less than 12 years of education (P<.001), nonsmokers (P<.001), and women weighing 77.1 kg (170 lb) or more (P=.003). Adjustment for confounders did not change these associations. Women reporting vomiting were less likely to experience miscarriage or stillbirth (P=.002) and delivery before 37 weeks' gestation (P=.004), but there was no difference in infant birth weight between mothers with and without vomiting (P =.48). Women who vomit in one pregnancy are more likely to vomit in subsequent pregnancies than are comparable women who did not vomit.