Kate Middleton, the duchess of Cambridge, went home today (Dec. 6) after spending four days in the hospital being treated for severe morning sickness, also known as hyperemesis gravidarum, according to news reports.
Hyperemesis gravidarum affects about 1 percent of pregnant women, usually goes away during the second half of pregnancy, and typically does not cause serious complications in the mother or child, according to the National Institutes of Health. Indeed, Middleton appears to be recuperating. However, the condition can cause malnutrition and dehydration, and has been associated with some conditions. Here are three health risks linked to severe morning sickness:
Preterm birth: A study of more than 81,000 women found that those who experienced nausea and vomiting during pregnancy that interfered with their life were 23 percent more likely to deliver their baby before 34 weeks compared with women who said their morning sickness did not substantially affect their lives. (A baby is considered preterm when he or she is born before 37 weeks of pregnancy.) The reason for the link could not be determined from the study, but poor nutrition and too little weight gain may contribute to the risk, the researchers said. The study was presented at this year's Society for Maternal-Fetal Medicine's annual meeting in Dallas.
Risk of psychological disorders in kids: A study published last year found children born to mothers withhyperemesis gravidarum were about 3.5 times more likely to have behavioral or emotional problems, such as anxiety, depression or bipolar disorder when they grew up, than children of mothers without the disorder. Mothers in the study said they had lost at least 5 percent of their weight when they had hyperemesis gravidarum. The researchers speculate that stress and anxiety during pregnancy, as well as malnutrition, may affect the fetus' brain as it develops. Also, women with the condition may experience psychological or physical problems after their pregnancy that hinder their ability to bond with their child. However, women in the study had been pregnant many years ago, when treatment of hyperemesis gravidarum was not common, so the risk for today's children may be lower, the researchers said.
Brain disorder: A 25-year old pregnant women in India developed a brain condition known as Wernicke's encephalopathy after three months of vomiting, which resulted in weight loss, according to a report published in May in the Journal of the Association of Physicians of India. She experienced loss of vision and problems with balance and walking. A scan of her brain show changes known to be consistent with the disorder, the researchers said. Wernicke's encephalopathy is caused by a deficiency of vitamin B1 (thiamine), according to the National Institutes of Health. Patients can experience confusion, problems with muscle coordination and vision changes. It is most often seen in alcoholics, but can develop in people who have problems absorbing food, such as individuals who have undergone gastric bypass surgery. The report describes the case of just one woman, and this condition is not known to be common among women with hyperemesis gravidarum.
Pass it on: Hyperemesis gravidarum typically does not cause serious complications, but has been linked to some health risks.
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Rachael is a Live Science contributor, and was a former channel editor and senior writer for Live Science between 2010 and 2022. She has a master's degree in journalism from New York University's Science, Health and Environmental Reporting Program. She also holds a B.S. in molecular biology and an M.S. in biology from the University of California, San Diego. Her work has appeared in Scienceline, The Washington Post and Scientific American.