Britain's Prince William and his wife, Catherine, are expecting their first child, but her severe morning sickness was attracting the most questions Monday.
The Duchess of Cambridge has been hospitalized for severe vomiting, called hyperemesis gravidarum, according to St. James's Palace.
Though the condition doesn't typically endanger mother or child, "it is pretty miserable," says Kecia Gaither, director of maternal fetal medicine at Brookdale University Hospital and Medical Center in Brooklyn, N.Y.
Less than 1% of all pregnant women are hospitalized for vomiting, says George Macones, spokesman for the American College of Obstetrics and Gynecology. The group advises women who can't keep food down for 24 hours or more to call a doctor. In severe cases, like Kate's, women can become dehydrated from lack of fluids.
They may need to be hospitalized for a few days so doctors can administer intravenous fluids as well as anti-nausea medications, Macones says.
They also may need potassium or other electrolytes, Gaither says. In "exceedingly rare" cases, women may need to be in intensive care. Doctors can typically intervene early to prevent serious complications.
In most cases, nausea and vomiting end by the second trimester, 13 or 14 weeks into a pregnancy, Macones says. A few women may have severe vomiting throughout pregnancy and require intravenous nutrition.
There's no reason to believe excessive vomiting is caused by a problem with the baby, Macones says, but it can be more common in women carrying twins or triplets.
Morning sickness is believed to be caused by rapidly rising levels of the hormone HCG, human chorionic gonadotropin, which is released by the placenta, the National Institutes of Health says.
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