THURSDAY, April 29 (HealthDay News) -- The daughters of women who suffered from a severe form of morning sickness are three times more likely to be plagued by it themselves, Norwegian researchers report.
This form of morning sickness, called hyperemesis gravidarum, involves nausea and vomiting beginning before the 22nd week of gestation. In severe cases, it can lead to weight loss. The condition occurs in up to 2 percent of pregnancies and is a common cause of hospitalization for pregnant women. It is also linked with low birth weight and premature birth, the researchers said.
The new study suggests "a strong influence of maternal genes" on the development of the condition, said lead researcher Ase Vikanes, a graduate student at the Norwegian Institute of Public Health in Oslo.
"However, environmental influences along the maternal line, shared risk factors such as life styles reflected in BMI (body mass index) and smoking habits, infections and nutrition might also be contributing to the development of hyperemesis gravidarum," she added.
The report is published in the April 30 online edition of the BMJ.
According to Vikanes, hyperemesis gravidarum was once thought to be caused by psychological issues, "such as an unconscious rejection of the child or partner." But her team wanted to see if genetics was actually the culprit.
For the study, Vikanes's team collected data on 2.3 million births from 1967 to 2006. They tracked the incidence of hyperemesis gravidarum in more than 500,000 mother-daughter pairs and almost 400,000 mother-son pairs.
They found that if a mother had the condition, her daughter was three times more likely to develop it as well. However, there is no increased risk to the female partners of men whose mothers suffered through it.
Vikanes hopes the finding adds new insight into this condition. Besides helping to illuminate possible causes, "our findings might help health care personnel who treat and counsel women with a family history of hyperemesis gravidarum," she said.
Brad Imler, president of the American Pregnancy Association, said that "hyperemesis gravidarum is a serious condition that creates health risks for both the mother and the baby. "Research into the causes and treatments of this condition are essential for discovering ways to alleviate the condition along with the health risks related to it," he said.
Imler cautioned that a three-fold increase in risk is not something that should cause fear among pregnant women. That "means going from 1 in 100 to 3 in 100 incidences," he noted.
Genetics appears to have a relationship with the condition, Imler said. "However, it would be important to have further research that controlled for environmental factors, dietary intake, and lifestyle habits, which also tend to be carried on from one generation to the next," he added.
Dr. Gene Burkett, a professor of obstetrics and gynecology at the University of Miami Miller School of Medicine, said that, "for a long time we have thought there is a familial component, and this gives us the first real information on which we can say, 'Yes, there seems to be something that we need to pursue.'"
However, Burkett said that the results need to be replicated in different populations before one can be sure the link is genetic.
More informationFor more information on morning sickness, visit the U.S. National Library of Medicine.