Kate Middleton is pregnant , ladies and gentlemen. The exciting announcement is tempered, however, by news that The Duchess of Cambridge has been hospitalized due to acute morning sickness called hyperemesis gravidarum, a rep for the Royal Family confirms .

The rep told Fox News :

"The Duchess was admitted this afternoon to King Edward VII Hospital in Central London with Hyperemesis Gravidarum... As the pregnancy is in its very early stages, Her Royal Highness is expected to stay in hospital for several days and will require a period of rest thereafter."

As Reuters reports, the royal baby's due date has not been announced. The Palace has only said Kate is in the very early stages of pregnancy. Their source, according to People, says the couple decided to "be open" about Kate's pregnancy because of the hospital stay.

According to The National Center for Biotechnology Information, hyperemesis gravidarum is "extreme, persistent nausea and vomiting during pregnancy that may lead to dehydration."

This type of nausea and vomiting during pregnancy occurs if mom-to-be is carrying twins (possibly two royal babies?) or if she has a hydatidiform mole .

About 70-80 percent of pregnant women experience some type of morning sickness, but only 1-2 percent suffer from hyperemesis gravidarum, according to BabyCenter's hyperemesis support group page . The main difference, AmericanPregnancy.org says , is that nausea caused by morning sickness usually subsides after 12 weeks, but for women with hyperemesis gravidarum, the nausea continues after that point. Also, vomiting caused by this condition causes severe dehydration. Common morning sickness does not.

To treat hyperemesis gravidarum, hospitals use IVs, tube feeding, and medications such as metoclopramide, antihistamines, and antireflux medications. For less severe cases, AmericanPregnancy.org lists treatments such as bedrest, acupressure, herbs and hypnosis.