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Rare, Severe Form of Morning Sickness Appears to Be Genetic

TUESDAY Nov. 16, 2010 -- A rare, but severe and potentially life-threatening form of morning sickness, called hyperemesis gravidarum, may be hereditary, researchers say.

Each year about 60,000 pregnant women in the United States are hospitalized due to hyperemesis gravidarum (HG), marked by chronic vomiting so frequent and severe that it can cause weight loss, dehydration and psychological trauma. The condition, although almost always treatable, can in rare cases lead to complications that force women to terminate their pregnancies.

The new study of 650 women included those who had been diagnosed with HG and a control group of women who had had at least two pregnancies and had not had HG. Women with sisters who had HG were 17.3 times more likely to develop the condition, the investigators found.

Women with HG were more than five times more likely than the control participants to have a sister who had severe morning sickness or HG. In addition, 33 percent of women with HG had an affected mother, compared with 8 percent of controls, according to the report.

Among women who had information about their grandmothers' pregnancies, 18 percent of HG patients had a maternal grandmother with HG and 23 percent had a paternal grandmother who had had the condition, the study authors noted.

"Pregnant women with a family history of extreme nausea in pregnancy should be aware that they may have it too, and health care providers should take a family history of nausea in pregnancy at the first visit with an obstetrician," lead author Marlena Fejzo, an assistant professor of hematology-oncology at the David Geffen School of Medicine at the University of California, Los Angeles, said in a UCLA news release. "The high familial prevalence strongly suggests a genetic component to this condition," Fejzo added.

"Because the incidence of hyperemesis gravidarum is most commonly reported to be 0.5 percent in the population, and the sisters of cases have as much as an 18-fold increased familial risk for HG compared to controls, this study provides strong evidence for a genetic component to extreme nausea and vomiting in pregnancy," the study authors concluded.

The study, led by researchers from the University of California, Los Angeles and the University of Southern California, was released online in advance of publication in an upcoming print issue of the American Journal of Obstetrics & Gynecology.

More information

The U.S. National Library of Medicine has more about hyperemesis gravidarum.

Posted: November 2010


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