Severe morning sickness: Gene found as cause for condition Duchess of Cambridge had

A gene has been discovered as the main cause for the same severe morning sickness condition the Duchess of Cambridge suffered from in a 'breakthrough' study.

Finding a cause for the often misunderstood, debilitating illness now provides the hope of new treatments for the one to three in 100 pregnant women who experience its debilitating effects.

Hyperemesis gravidarum (HG) is much worse than normal pregnancy symptoms, with nausea and vomiting far more severe. It has been associated with an increased risk of termination, preterm birth, suicidal thoughts and post-traumatic stress disorder, as reported in the recent study.

Most people who experience HG in their first pregnancy will go through it again if they have more babies. Kate, 40, suffered from it in all three of her pregnancies with George, eight, Charlotte, six, and Louis, three, and ended up needing hospital treatment.

Appearing on Giovanna Fletcher’s podcast, Happy Mum, Happy Baby, Kate has previously said, "I got very bad morning sickness, so I’m not the happiest of pregnant people."

She added, "Lots of people have it far, far worse, but it was definitely a challenge. Not just for me but also for your loved ones around you – and I think that’s the thing – being pregnant and having a newborn baby and things like that, impacts everybody in the family."

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Many past theories have tried to pinpoint the condition as being 'psychological' or an 'extreme reaction' to normal morning sickness, overlooking its seriousness and preventing progress with effective treatments.

This explains why the new groundbreaking evidence – as published in BJOG: An International Journal of Obstetrics and Gynaecology – is so important. It found abnormalities in a specific gene that is linked to being the main cause of HG.

Pregnancy Sickness Support chairperson and nurse specialist, Dr Caitlin Dean, said on the research, "This is a very exciting development for the millions of people whose lives are affected by the horrific condition hyperemesis gravidarum."

"By understanding what causes the condition we edge closer to a cure, rather than the current ineffective treatments we have which only serve to mask the symptoms a bit.

Dr Dean added, "Knowing there is a biological reason for their suffering is also extremely validating for people who are frequently dismissed when asking for help."

Read more: Hyperemesis gravidarum isn't merely morning sickness - it's much more serious than that

Watch: Amy Schumer battling extreme morning sickness in hospital

In the pioneering study, researchers compared the genes of 926 women with HG pregnancies with 660 women with normal levels of nausea and vomiting while pregnant.

They discovered one gene in particular that behaved slightly differently – a hormone found at high levels in the placenta. The cellular stress hormone 'GDF15' acted abnormally by sending extreme nausea signals to the brain.

As well as being linked to HG, it has also been found in relation to causing cancer cachexia, a wasting syndrome (causing a complex change in the body) that similarly causes weight loss, malnutrition and loss of appetite.

With clinical trials underway for cachexia drugs that block the GDF15 signalling pathway, there is potential for treatments to reduce nausea and weight loss – and similar medications may also benefit HG patients.

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Dr Marlena Fejzo, researcher at the Keck School of Medicine at the University of Southern California, said: "For generations, it's been thought that HG was either psychological in nature or caused by the hCG pregnancy hormone, so this breakthrough leads us in a new direction.

"Our study provides compelling evidence that abnormalities in the GD15 gene and the protein it codes for are the main cause of HG."

Read more: Greg Rutherford's pregnant fiancée Susie Verrill shares gruelling reality of hyperemesis gravidarum

So what does this mean for sufferers nationwide? "Providing clinicians and patients with an evidence-based cause of HG may lessen the historical stigma and allow patients to be taken more seriously, resulting in improved care and healthier mothers and babies," Dr Fejzo added.

"HG patients and their babies can suffer greatly and this study provides long overdue progress toward understanding the disease."

Signs and symptoms of HG include prolonged and severe nausea and vomiting, being dehydrated, weight loss and low blood pressure (hypotension) when standing. Unlike regular pregnancy sickness, HG doesn't always improve by 16 to 20 weeks, and may not clear up completely until after the baby is born.

It is important to seek medical advice and help from your GP or midwife as soon as possible if you have severe nausea and vomiting.

Additional reporting SWNS.