May 1, 2010
Mother, Daughter Morning Sickness Link Found
Norwegian researchers say that pregnant women are three times more likely to suffer from severe morning sickness if their mothers did.
About 2 percent of women suffer from excessive nausea and vomiting in pregnancy, which can require hospital treatment.
Experts said the results might help women better understand their risk.
Hyperemesis is an excessive sickness that starts before the 22nd week of pregnancy, which can lead to dehydration and weight loss.
This is the most common cause of admission to hospital in early pregnancy and can lead to low birth weight and premature birth.
Previous studies have attributed the condition to "psychological causes," according to the researchers.
The researchers analyzed birth records from 1967 to 2006, which included information on pregnancy complications.
The study found that daughters of women who had the condition during their pregnancy had a 3 percent higher risk, compared with 1 percent in those whose mothers did not have it.
However, there was no increased risk to the female partners of sons that had mothers with previous conditions.
The team said that even though the results found a genetic link between mothers and daughters, it is also possible there are lifestyle or environmental factors that are shared between mothers and daughters that increase the risk.
The researchers said the study "shed a new light" on the causes of hyperemesis in pregnancy.
"It might lead to a better appreciation of the underlying biology," they added.
Catherine Nelson-Piercy, a consultant obstetric physician at Guy's and St. Thomas' Foundation Trust in London, told BBC News that clinicians might benefit from a better understanding of the genetic risks of hyperemesis when counseling women about the risk of recurrence in future pregnancies.
She said most women were under-treated due to the legacy of thalidomide, despite the availability of safe drugs. Thalidomide is a drug given for morning sickness in the 1960s that caused birth defects.
"It can be extremely debilitating, women can't work, can't look after their families and they need to be admitted to hospital," Piercy told BBC.
"It is safe to take anti-sickness drugs and it's better for the baby and the pregnancy to treat this condition than let the woman get very severely ill and risk complications."
The spokesman for the Royal College of Obstetrics and Gynecology, Patrick O'Brien, said the study showed growing evidence that many conditions in pregnancy, like diabetes or high blood pressure, were linked to a "genetic predisposition."
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