Scientists finally discover cause of extreme pregnancy sickness

The end of morning sickness? Scientists finally discover cause of common pregnancy woe in massive breakthrough

  • Up to 70 per cent of pregnant women suffer the misery of nausea and vomiting

A safe drug taken before women get pregnant, to prevent morning sickness, could be on the horizon following a major scientific breakthrough.

Up to 70 per cent of pregnant women suffer the misery of nausea and vomiting.

Scientists previously found a hormone which appeared to trigger morning sickness in the brain, but have spent almost a decade trying to understand how it works.

Their breakthrough is the new discovery that this hormone, called GDF15, needs to be at a high level in a pregnant woman’s body, but she also needs to have had a low level of it before pregnancy, in order to suffer morning sickness.

A sudden surge in the hormone, above what a woman had previously experienced, is what appears to cause the nausea and vomiting.

The condition is perhaps best known for affecting Catherine (above in April 2013), Princess of Wales, who was hospitalised for several days in 2013 while pregnant with her first child, Prince George

This discovery paves the way for a drug which women could take before they even conceive, to top up their GDF15 so they are far less likely to develop morning sickness.

Metformin, currently given to people with type 2 diabetes, is a promising candidate, and researchers are preparing to test it in women as early as next year.

Such a pre-pregnancy drug would be a lifeline for women — many of whom suffer through morning sickness, and are afraid to take anti-sickness medications during pregnancy despite evidence for their safety.

It could also provide much-needed hope for hyperemesis gravidarum, a debilitating form of sickness during pregnancy which is far more severe than morning sickness and affects up to three per cent of pregnancies.

Famously suffered by the Princess of Wales, Kate Middleton, this life-threatening condition can cause sickness dozens of times a day, with some women ending up being hospitalised with severe dehydration.

What is hyperemesis gravidarum?

Hyperemesis gravidarum (HG) is a condition that causes persistent and excessive vomiting during pregnancy.

Sufferers can be sick lots of times every day and be unable to keep food or water down, impacting their daily life.

It is unlikely to harm the baby, but if it causes a women to lose weight during pregnancy there is an increased risk their baby will have a low birth weight.

It is different to sickness during pregnancy — often called morning sickness — which is normal and affects eight in 10 pregnant women. For most, this stops or improves around weeks 16 to 20.

Meanwhile, HG may not get better by this point and can last until the baby is born.

Symptoms of HG include prolonged and severe nausea and vomiting, being dehydrated, weight loss and low blood pressure.

Being dehydrated raises the risk of having a blood clot — deep vein thrombosis — but this is rare.

It is not clear what causes the condition, or why some women get it and others don’t.

Some experts think it may be linked to the changing hormones in the body that occurs during pregnancy.

And there is some evidence that it runs in families and women who suffered it during their first pregnancy are more likely to have in any subsequent pregnancies.

Women suffering from HG can be given medicine to improve their symptoms, such as anti-sickness drugs, vitamins B6 and B12 and steroids.

Some women have to be admitted to hospital if their nausea cannot be controlled with medicines at home.

They may require fluids and anti-sickness drugs to be administered through an IV.

Professor Sir Stephen O’Rahilly, from the University of Cambridge, led a study presenting the new findings, and said: ‘Severe nausea and vomiting during pregnancy is common and very disabling for women.

‘Our findings convincingly demonstrate the role of the hormone GDF15, and should transform the way we treat morning sickness or hyperemesis gravidarum, to reduce the suffering of women.’

Women have a low level of the GDF15 hormone in their body before becoming pregnant, but it is topped up during pregnancy.

Researchers also now know it is the pregnancy itself which increases the hormone, as GDF15 is produced as the placenta is formed.

The scientists already had early evidence GDF15 was typically higher in women with pregnancy sickness, and confirmed this in the new study using high-quality blood tests from more than 400 women.

But this was clearly not the full story, as women with very high GDF15 did not always have morning sickness or hyperemesis gravidarum (HG).

To understand how the hormone worked better, researchers looked at women with a rare genetic mutation known to raise their risk of HG in pregnancy 10-fold.

They discovered for the first time that these women had very low levels of the hormone GDF15 before pregnancy.

The missing puzzle piece, suggesting women need both low pre-pregnancy GDF15 and high GDF15 during pregnancy to get sick, was confirmed using a questionnaire given to 20 new mothers with the blood disorder thalassaemia major.

These women, whose condition means they never have low pre-pregnancy GDF15, also reported hardly any morning sickness compared to other women.

A further study in mice found those given a sudden injection of GDF15, like women experience in pregnancy, only appeared to feel sick and reduced their food intake if they had started out with a low level of GDF15.

The detailed study, carried out by an international team of scientists and published in the journal Nature, suggests building up a woman’s tolerance to the hormone prior to pregnancy, by giving her a drug containing it, could hold the key to preventing morning sickness.

The researchers say their data suggests a drug doubling pre-pregnancy GDF15 levels could halve the risk of someone developing HG.

Metformin is likely to first be trialled in women who have had HG previously and hope to avoid it in future pregnancies.

Preventing the hormone from triggering nausea, using an injection to block it, could be another potential treatment approach, although this would need to be safe for pregnant women.

It is likely morning sickness was necessary in hunter-gatherer times, to put women off foods which may be toxic to her baby, but it no longer serves a function.

Extreme morning sickness meant I almost terminated my pregnancy

Throwing up as often as 30 times a day became the new normal for Charlotte Howden during her pregnancy in 2016.

But she was initially given only the usual advice for morning sickness, like eating little and often, and trying ginger.

It took until she was three months pregnant to realise from reading her hospital notes that she had hyperemesis gravidarum, which is a completely different condition to morning sickness, and can be life-threatening for a mother and baby.

Mrs Howden, 40, said: ‘Many people, from health professionals at the beginning to even friends and family, would think I just had morning sickness and should be able to pull myself together and cope with it.

‘You feel so isolated and broken, dealing with such extreme sickness during your pregnancy, which is so different to what most other people experience.’

The mother of one, who lives with her husband William and seven-year-old son Henry in the village of Curdridge in Hampshire, began feeling nauseous around week six of her pregnancy.

Throwing up as often as 30 times a day became the new normal for Charlotte Howden during her pregnancy in 2016. But she was initially given only the usual advice for morning sickness, like eating little and often, and trying ginger. Pictured with her seven-year-old son Henry

But within only another week, she was being sick dozens of times daily and could not keep any food down.

Even a sip of water, or swallowing her own saliva, could trigger a fit of vomiting.

It took weeks to be given medication, which made her sleep for 20 hours a day, and did not prevent her needing to be admitted to hospital every couple of weeks with severe dehydration caused by the vomiting.

Mrs Howden, now chief executive of the charity Pregnancy Sickness Support, said: ‘I begged the consultant to help me because I was very close to making the decision to terminate my pregnancy.

‘It took until week 16 of the pregnancy until I was on the right treatment.’

The campaigner is desperately grateful for the scientific breakthrough which raises hope for a future treatment for HG.

She said: ‘When you are suffering from a condition and no one can tell you why, you start to think, is it me? Is it something I’ve done?

‘I hope this will pave the way for a treatment to hugely reduce the risk of getting HG, and in the meantime the publicity will encourage doctors to recognise this condition and provide women with the care they need.’

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