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What causes morning sickness? Scientists blame this hormone

Side view of a doctor touching a pregnant woman's belly, feeling the baby inside the tummy. medical pregnancy checkup concept

(NewsNation) — Scientists have identified the cause of severe morning sickness. According to a University of Cambridge-led study published Wednesday in the journal Nature, nausea and vomiting during pregnancy are connected to a single hormone.

GDF15 is a hormone acting on the brainstem. The production of GDF15 in the fetal part of the placenta and a mother’s sensitivity to it can result in severe morning sickness, researchers wrote.


“The baby growing in the womb is producing a hormone at levels the mother is not used to. The more sensitive she is to this hormone, the sicker she will become,” Cambridge professor Stephen O’Rahilly explained.

The amount of the GDF15 hormone in a woman’s blood during pregnancy and her exposure to it prior to becoming pregnant sometimes also determines the severity of morning sickness.

“The researchers showed that the degree of nausea and vomiting that a woman experiences in pregnancy is directly related to both the amount of GDF15 made by the fetal part of placenta and sent into her bloodstream, and how sensitive she is to the nauseating effect of this hormone,” the University of Cambridge said in a news release.

The hormone is made at low levels outside of pregnancy in all tissues. Cambridge notes that women with normally low levels of GDF15 in their blood have a higher risk of developing severe nausea and vomiting during pregnancy.

As many as seven in 10 pregnancies are impacted by nausea and vomiting. But Cambridge says in between one and three in 100 pregnancies, morning sickness can be severe and sometimes life-threatening. This is often called hyperemesis gravidarum, which is the most common cause of admission to a hospital for women during their first three months of pregnancy.

Dr. Marlena Fejzo from the Department of Population and Public Health Sciences at the University of Southern California was the study’s co-author. She has personal experience with hyperemesis gravidarum.

“When I was pregnant, I became so ill that I could barely move without being sick. When I tried to find out why, I realized how little was known about my condition, despite pregnancy nausea being very common,” Dr. Fejzo said.

The study’s discovery about GDF15 and pregnancies points to a possible way to prevent morning sickness and hyperemesis gravidarum.

Mice exposed to acute, high levels of GDF15 showed signs of appetite loss, indicating they may be experiencing nausea. However, mice treated with a long-acting form of GDF15 did not have similar symptoms when exposed to acute levels of the hormone.

With that in mind, researchers think building up a woman’s tolerance to GDF15 before pregnancy could be the key to preventing sickness.

“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,” Dr. Fejzo said.

The “GDF15 linked to maternal risk of nausea and vomiting during pregnancy” study published by Nature can be found here.