The Duke and Duchess of Cambridge are expecting their third baby and, as with her fist two pregnancies, Kate is suffering from Hyperemesis Gravidarum – a severe form of morning sickness which can result in dehydration and weight loss.

Dr James Nicopoullos, Consultant Gynaecologist and Subspecialist in Reproductive Medicine & Surgery at The Lister Hospital, London spoke to us about the potential impact of the condition on the royal baby, and explains what expectant mothers can do to ease the symptoms of Hyperemesis Gravidarum.

What is Hyperemesis Gravidarum?

Hyperemesis Gravidarum (HG) is essentially an extreme form of morning sickness. “The key symptoms always begin in the first trimester, most commonly at 6-8 weeks of pregnancy and they tend to resolve in the majority by week 14-16,” says Dr Nicopoullos.

“At least 50% of women suffer from some nausea and vomiting, but in only a small proportion (<1%) does this become so severe that it leads to an inability to tolerate enough oral fluids to maintain hydration which can lead to dehydration and occasionally weight loss, imbalances in important electrolytes in the body (such as sodium and potassium) and poor nutrition.”

What causes the condition?

It is not fully understood why some women suffer from this condition and other don’t, although hormonal, mechanical and psychological factors may all play a role.

“Early pregnancy hormone (hCG) stimulates the thyroid gland the level of hCG and thyroid hormones seem to correlate with the severity of symptoms in some but not all women,” says Dr Nicopoullos.

“Pregnancy also naturally leads to certain mechanical changes that predispose to the symptoms so are exacerbating factors but unlikely to be the underlying cause (such as changes in pressure in the oesophagus and slower emptying of stomach contents).”

Can it harm the baby?

It is very rare for HG to lead to serious consequences for either the mother or baby, and these only occur if the proper treatment isn’t received.

“For mum, the main concern is nutritional deficiencies,” says Dr Nicopoullos. “In particular Vitamin B1 (Thiamine) deficiency can cause “Wernicke’s Encephalopathy” where there can be significant visual disturbance and confusion and lead to learning difficulties if left untreated.

“This is exceptionally rare as most will be treated with the appropriate fluid to avoid this and supplemented with Thiamine. On the rare occasion that a women suffers Wernicke’s emcephalopathy this leads to a fetal death in 40% of cases.”

In some instances, persistent vomiting and dehydration can lead to low sodium levels which in rare cases can cause respiratory problems and seizures. Frequent, violent retching, can also lead to a “Mallory Weiss Teat”, a small tear and bleeding in the oesophagus.

“Thankfully, in general, HG shows no increase in risk to baby with no increase in congenital birth defects,” says Dr Nicopoullos. “If severe and leading to maternal weight loss and nutritional problems, the pregnancy should be monitored a little more closely to assess fetal weight as this can decrease.

“If the dehydration is significant, there is an increase in the risk of potentially life-threatening blood clots. This is another reason for a low threshold for admission so preventative measures can be taken if needed.”

Managing the condition

How can expectant mothers ease their symptoms?

Whilst time is the only real cure for the symptoms of Hyperemesis Gravidarum, there are some things expectant mums can do to help minimise their impact on their lives:

  • Tackle the symptoms as early as possible when they are easier to deal with and before they have a chance to cause significant dehydration and any nutritional problems
  • Seek guidance from an experienced medical practitioner as soon as possible
  • Test for underlying causes of nausea (such as urine infections or taking iron supplements) and discuss taking one of the many safe anti-sickness medications
  • If fluids are not being tolerated, intravenous fluids and anti-sickness medications should be offered until symptoms have resolved. This may be required several times over the course of early pregnancy

If you are suffering from Hyperemesis Gravidarum or any level of pregnancy sickness, visit the charity Pregnancy Sickness Support (PSS) for help and advice.