What is hyperemesis gravidarum?
Extreme morning sickness or hyperemesis gravidarum affects up to one in 50 women in pregnancy. Vomiting can be so severe that no food or drink can be kept down. It typically subsides by week 20 of pregnancy, but can last much longer and even throughout the entire pregnancy.
Jules Robertson, a midwife for the pregnancy and baby advice charity Tommy's, said:
"We are delighted to hear that the Duke and Duchess of Cambridge are expecting a baby, and we hope Catherine makes a speedy recovery from hyperemesis gravidarum - this is a severe form of nausea and vomiting in pregnancy.
"It is different from the more common nausea and vomiting known as 'morning sickness', as it is normally more persistent. If pregnant women are vomiting several times during the day and unable to keep food or drink down, then they will need to be treated to help them cope with the symptoms, and stay nourished and hydrated. We advise that anyone experiencing this should see their GP or midwife to be checked.
"It is more common in early pregnancy, and by around 14-16 weeks the sickness should have gone - most of the time it is resolved by 20 weeks, and very occasionally it can continue throughout pregnancy."
What are the symptoms?
Women with hyperemesis gravidarum often lose weight (usually over 1023FFEB00&videoControlDisplayColor=VIRTUAL-Gallery-168899%