An extreme form of pregnancy-related nausea and vomiting known as hyperemesis gravidarum (HG) takes a heavy toll on thousands of women each year and can lead to hospitalization and pregnancy termination. But new research suggests pregnant women are not the only victims.

A joint study by USC and UCLA has found that children whose mothers suffered from HG while carrying them were 3.6 times more likely to suffer from anxiety, bipolar disorder and depression in adulthood than individuals whose mothers did not have the condition. HG sends some 285,000 women to the hospital in the United States each year.

The study is published in the August issue of the Journal of Developmental Origins of Health and Disease.

Earlier studies have found that children of women who experience nausea persisting beyond the first trimester of pregnancy have more attention and learning problems by age 12, said study co-author Marlena Fejzo, an assistant professor of maternal and fetal medicine at the Keck School of Medicine of USC and assistant professor of hematology-oncology at the David Geffen School of Medicine at UCLA. Other studies have found that poor fetal nutrition – a frequent result of HG – can lead to poor health in adulthood.

“Even though hyperemesis gravidarum can be a form of starvation and dehydration in pregnancy, no studies prior to this have been done to determine the long-term effects it has on the exposed unborn child,” Fejzo said.

HG often runs in families and in previous research, Fejzo and her colleagues found that women with a family history of the condition were up to 17 times more likely to suffer from it themselves.

The findings from the current study were based on surveys of women with HG who reported on the emotional and behavioral histories of their siblings. Of the 150 respondents, 55 had mothers who also suffered from the condition, so their siblings were exposed to HG in utero; 95 had mothers who did not experience HG and thus their siblings were not exposed. There was a total of 87 siblings from the exposed group (the “cases”) and 172 from the nonexposed group (the “controls”).

The researchers found that 16 percent of siblings from the exposed group had depression, compared with 3 percent from the nonexposed group; 8 percent from the exposed group was diagnosed with bipolar disorder, compared with 2 percent from the nonexposed group; and 7 percent from the exposed group suffered from anxiety in adulthood, compared with 2 percent from the nonexposed group.

“In all, among 17 diagnoses, 38 percent of the cases [those from the exposed group] are reported to have a psychological and/or behavioral disorder, as compared to 15 percent of controls,” the researchers wrote. “In this study, adults exposed to HG in utero are significantly more likely to have a psychological and/or behavioral disorder than nonexposed adults.”

These higher rates could stem from the mothers’ prolonged malnutrition and dehydration during fetal brain development. And the anxiety and stress that are common during and after HG pregnancies also may play a part, the researchers said.

The researchers noted that the study has limitations. For instance, it was based on recall and self-reporting, which can lead to biased or incomplete responses, so the rates of diagnoses within each group should be treated with caution, they said.

Still, the significant differences reported suggest that adults who were exposed to HG in utero could be at a nearly fourfold higher risk for lifelong neurobehavioral disorders in adulthood.

“HG is an understudied and undertreated condition of pregnancy that can result in not only short-term maternal physical and mental health problems but also potentially lifelong consequences to the exposed fetus,” the researchers concluded.

The Intramural Research Program of the National Institute of Child Health and Human Development funded the study. Additional study co-authors were Patrick Mullin and T. Murphy Goodwin of USC; Andrew Bray and Frederic Schoenberg of UCLA; Kimber W. MacGibbon of the Hyperemesis Education and Research Foundation; and Roberto Romero of the Department of Health and Human Services.