Genes determine who will suffer severe morning sickness

Hyperemesis gravidarum (HG), severe nausea and vomiting of pregnancy, appears to be influenced at least in part by genetics, according to new study findings.

Researchers at the University of Southern California-Los Angeles and the University of California-Los Angeles included in their study 207 women who experienced HG during their singleton pregnancies, required intravenous hydration, and had at least 1 sister who had been pregnant. They compared the women's responses to a survey with those of 110 of their friends who had relatively nausea-free pregnancies.

The researchers found that the women with sisters who experienced HG were 17 times more likely to experience HG themselves, and about one-third of them (33%) had mothers who experienced HG compared with 7.7% of the controls. Data also suggest that maternal and paternal grandmothers, mothers, and daughters share a higher risk of severe morning sickness and HG, and the researchers note it is unlikely that this commonality can be explained solely by shared environmental and cross-generational factors.

The study was supported by the Eunice Kennedy Shriver National Institute of Child Health and Human Development.

Zhang Y, Cantor RM, Macgibbon K, et al. Familial aggregation of hyperemesis gravidarum. Am J Obstet Gynecol. October 23, 2010. [Epub ahead of print.]