The crippling illness that affected Kate's third pregnancy

Team Be

Kate Middleton has just given birth to her third baby, and while the world is celebrating the boy's safe arrival, this pregnancy hasn’t been an easy one.

The Duchess of Cambridge was forced to announce that she was expecting earlier than planned, due to hyperemesis gravidarum - a condition she also suffered during her pregnancies with George and Charlotte, and which led to a hospital stay last year.

While Kate has since recovered and returned to her regular royal duties before going on maternity leave at Easter, her case has shone a light on the debilitating illness.

Kate suffered from hyperemesis gravidarum during her third pregnancy. Source: Getty

Hyperemesis gravidarum is acute morning sickness that develops during pregnancy. It causes women to suffer from severe nausea and vomiting, and sometimes requires the pregnancy to be managed with through extra hydration, medication and nutrients.

The condition is not very common, affecting about one in 100 soon-to-be-mothers, and symptoms are usually at their worst between four to seven weeks, but can last up to 15 weeks in some pregnancy cases. Some women may even suffer up until the very end of their pregnancy.

The cause of the condition is unknown, although it is thought to be caused by hormonal changes in pregnancy.

Kate returned to work after recovering from the condition, and went on maternity leave just before Easter. Photo: Getty

In guidelines published by the UK Royal College of Obstetricians & Gynaecologists in 2016, lead author Dr Manjeet Shemar, says: “Women suffering from nausea and vomiting and hyperemesis gravidarum can face a challenging time in early pregnancy. The more severe the condition, the more it can affect their day-to-day quality of life and mental health."


Understanding hyperemesis gravidarum

WHAT IS IT?

A severe form of nausea and vomiting affecting pregnant women that can put the mum and baby at risk because the woman can't retain and utilise food and fluids.

The Duchess is already mum mother to Prince George and Princess Charlotte. Source: Getty

SYMPTOMS

Constant nausea and severe vomiting that can lead to dehydration and cause an imbalance in electrolytes. Women can lose more than five per cent of their body weight as well as suffer headaches, fatigue, confusion, fainting and jaundice.

HOW COMMON IS IT?

It's estimated to affect about one per cent of pregnant women.

The Duchess, seen here in a pervious pregnancy, cancelled her royal duties in September because of the illness. Source: Getty

WHEN DOES IT START?

Usually between the first four to six weeks and symptoms don't usually improve until between 15 and 20 weeks but can last the entire pregnancy.

TREATMENT

Women with milder forms are advised to change diet, rest and take antacids. With more severe forms women are hospitalised so they can have their food and liquids closely monitored and usually require an intravenous drip.

CAUSES

Experts still don't fully understand the causes but experts describe it as a complex physiological disease with multiple causes. They say aggressive care early in pregnancy is vital to prevent life-threatening complications such as central pontine myolinolysis or Wernicke's encephalopathy.

Additional reporting by AAP.

William and Kate were married in 2011. Source: Getty

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