It can't be much fun being Kate right now, especially as she is all alone.
Prince William has left his wife's side for the evening.
He was filmed coming out of the hospital shortly after 8pm.
William had been with Kate all day after driving her to the hospital early this afternoon.
Kate is suffering a particularly acute form of morning sickness and is likely to be in hospital for several days. She is believed to be on a drip for liquid and food, and unable to hold any food down.
Women suffering from the condition may vomit as many as 30 times a day and can even vomit blood. The unusual form of morning sickness can in extreme cases last the duration of the pregnancy.
However, experts are saying there is no danger to mothe ror unborn child provided fluids and nutrients can be provided by a drip.
One mother who has suffered with hyperemesis gravidarum told the Daily Mail: "Imagine having a stomach bug that lasts for days and days, months and months - it is just relentless. Any movement, any sound, any smell just makes you vomit. I vomited 20 to 30 times a day for the first few months."