A joint study by UCLA and the University of Southern California 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 US each year.
The study is published in the August 2011 issue of the Journal of Developmental Origins of Health and Disease.
Prior 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 haematology-oncology at the David Geffen School of Medicine at UCLA and an assistant professor of maternal and foetal medicine at the Keck School of Medicine of USC. In addition, other studies have found that poor foetal 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 behavioural 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 didn't experience HG, and thus their siblings were not exposed. There were a total of 87 siblings from the exposed group (the "cases") and 172 from the non-exposed group (the "controls").
The researchers found that 16% of siblings from the exposed group had depression, compared with 3% from the non-exposed group; 8% from the exposed group were diagnosed with bipolar disorder, compared with 2% from the non-exposed group; and 7% from the exposed group suffered from anxiety in adulthood, compared with 2% from the exposed group.
"In all, among 17 diagnoses, 38% of the cases [those from the exposed group] are reported to have a psychological and/or behavioural disorder, as compared to 15% of controls," the researchers write. "In this study, adults exposed to HG in utero are significantly more likely to have a psychological and/or behavioural disorder than non-exposed adults."
These higher rates could stem from the mothers' prolonged malnutrition and dehydration during foetal brain development. In addition, the anxiety and stress that are common during and after HG pregnancies may also 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 very 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 foetus," the researchers concluded.
The Intramural Research Program of the National Institute of Child Health and Human Development funded this study.
Additional study co-authors were Andrew Bray and Frederic Schoenberg of UCLA; Patrick Mullin and T. Murphy Goodwin of USC; Kimber W. MacGibbon of the Hyperemesis Education and Research Foundation; and Roberto Romero of the Department of Health and Human Services.
