Scientists could be on the cusp of a ‘cure’ and better treatments for morning sickness after researchers discovered the reason some women become more sick than others.
Around half to two-thirds of pregnant women suffer some degree of the uncomfortable and debilitating vomiting condition during the first stages of pregnancy. In extreme cases some expectant mums can be hospitalised.
Now academics from the UK, US and Sri Lanka have revealed the condition is caused by exposure to the hormone GDF15 being produced by babies in the womb, with the severity of illness resting on how sensitive the mother is to the hormone.
It is hoped the discovery could help treat severe cases of the condition, which is known as hyperemesis gravidarum (HG), in an “effective and safe way”.
To better understand the condition, the team analysed data from women recruited to various studies, including at the Rosie Maternity Hospital in Cambridge.
They found the level of nausea experienced by women in pregnancy related to the amount of GDF15 produced by the fetal part of the placenta.The level of sickness also rested on how much of the hormone the woman had been exposed to prior to pregnancy.
Professor Sir Stephen O’Rahilly, director of the Medical Research Council metabolic diseases unit at the University of Cambridge, said: “Most women who become pregnant will experience nausea and sickness at some point, and while this is not pleasant, for some women it can be much worse – they’ll become so sick they require treatment and even hospitalisation.
“We now know why: the baby growing in the womb is producing a hormone at levels the mother is not used to.”
GDF15 is made at low concentration in most of the body’s organs. A woman with lower levels in her blood outside of pregnancy may be at a higher risk of developing severe morning sickness in pregnancy, known as HG, researchers said.
HG can lead to prolonged periods of vomiting, dehydration and weight loss. Treatments include anti-sickness medicines and steroids, but some women may require hospitalisation and intravenous fluids.
Studies in which mice were exposed to high levels of GDF15 showed a loss of appetite, while mice given a long-acting form of GDF15 did not show the same symptoms when exposed to similar levels of the hormone.
The team said building up a tolerance prior to getting pregnant could prevent sickness.
Researchers also said women with the inherited blood disorder thalassemia, which causes higher levels of GDF15 outside of pregnancy, experienced little to no nausea or vomiting when pregnant.
The findings, published in Nature, could help find better treatments for HG, according to co-author Dr Marlena Fejzo, of the department of population and public health sciences at the University of Southern California.
She added: “When I was pregnant, I became so ill that I could barely move without being sick. When I tried to find out why, I realised how little was known about my condition, despite pregnancy nausea being very common.
“Hopefully, now that we understand the cause of hyperemesis gravidarum, we’re a step closer to developing effective treatments to stop other mothers going through what I and many other women have experienced.”