Just about every pregnant woman experiences morning sickness, but this part of pregnancy can be more than just unpleasant. When morning sickness becomes a condition known as hyperemesis gravidarum (HG), it can cause seizures and premature birth. The Duchess of Cambridge, Kate Middleton, has been hospitalized with HG and is undergoing treatment.
Hyperemesis gravidarum is a potentially dangerous type of morning sickness that is characterized by severe nausea, vomiting, weight-loss and electrolyte disturbance.
"It's not unusual for pregnant women to get morning sickness, but when it gets to the point where you're dehydrated, losing weight or vomiting so much you begin to build up (toxic) products in your blood, that's a concern," said Dr. Kecia Gaither, director of maternal fetal medicine at Brookdale University and Medical Center in New York.
About one in fifty pregnant women are affected by this condition. It tends to be more common in younger women who are pregnant for the first time or those expecting more than one baby.
Physicians are not sure what causes HG but suspect it could be linked to hormonal changes or nutritional problems. Spikes in the hormones estrogen, progesterone and human chorionic gonadotropin (hCG) may be contributors to HG. Low weight and sluggish digestion may also be factors.
While not all pregnant women with HG require hospitalization, some do. Treatment may include IV fluids to treat dehydration, anti-nausea medication, nutritional supplements plus bed rest.
If HG is caught early and treated, physicians say that there are no long-term effects for either the mother or the child. If left untreated, there is a risk of the mother developing neurological problems, including seizures, or delivering the baby pre-term. The condition usually ends by the second trimester.
"The rest of the pregnancy could be entirely uneventful," Gaither said, adding that pregnant women treated for the condition are usually advised to avoid fatty foods that could aggravate the problem.
Not even a duchess can escape the unpleasantness of morning sickness, Kate just happens to have a particularly severe form. People around the world are wishing her a speedy recovery.
If you are a mother-to-be experiencing severe nausea and vomiting talk to your OB-GYN and see if your pregnancy needs more extensive monitoring.
Sources: http://healthland.time.com/2012/12/04/why-a-pregnant-kate-middleton-is-in-the-hospital
http://news.msn.com/world/explainer-why-kate-is-in-hospital-for-morning-sickness
Dr.
Sue Hubbard is an award winning pediatrician and medical editor for
www.kidsdr.com. She is a native of Washington, D.C. who travelled south
to attend the University of Texas at Austin and never left. 
