Scientists identify the cause of severe morning sickness

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   In a recent study published in the journal Nature, scientists revealed that the notorious nausea and vomiting experienced during the initial stages of pregnancy can be attributed mainly to a single hormone. This breakthrough discovery holds promise for developing more effective treatments, particularly for severe cases of morning sickness.

The identified culprit behind these symptoms is a hormone known as GDF15, a finding consistent with previous research. The study highlighted that the levels of this hormone circulating in a woman's blood during pregnancy, along with her exposure to it before conception, significantly influence the intensity of her symptoms.

The statistics paint a familiar picture, with over two-thirds of pregnant women grappling with nausea and vomiting in the first trimester. Alarmingly, about 2% of women face a more severe condition called hyperemesis gravidarum, characterized by relentless vomiting and sickness throughout the entire pregnancy. This condition not only leads to malnutrition, weight loss, and dehydration but also raises the stakes for preterm birth, preeclampsia, and blood clots, posing severe threats to both the mother and the fetus.

Despite its prevalence, hyperemesis, a severe form of nausea and vomiting during pregnancy, often goes overlooked by doctors who may dismiss its intense symptoms as psychological. It's worth noting that hyperemesis is the leading cause of hospitalization in early pregnancy, a fact experts emphasize. While public figures like Kate Middleton and Amy Schumer have shed light on the condition in recent years, hyperemesis remains insufficiently studied.

Dr. Marlena Fejzo, a geneticist at the University of Southern California Keck School of Medicine and a co-author of a recent study, has been dedicated to this issue for two decades. Having experienced the agony of hyperemesis during her own pregnancy in 1999, she understands the challenges firsthand. Despite her dire situation, her doctor dismissed her symptoms, attributing them to a quest for attention. Eventually, she was hospitalized and suffered a miscarriage at 15 weeks.

Frustrated by the lack of research funding from the National Institutes of Health, Dr. Fejzo turned to 23andMe, a popular genetic testing company. Through surveys of tens of thousands of customers, she discovered a genetic link to hyperemesis. Her 2018 paper revealed that individuals with hyperemesis often carry a variant in a gene for GDF15.

Hormones act as messengers in the body, and GDF15, released in response to stress like infection, plays a crucial role. The hormone's receptors are concentrated in a specific part of the brain responsible for triggering feelings of sickness and inducing vomiting, providing valuable insights into the physiological mechanisms behind hyperemesis. Dr. Fejzo's efforts underscore the need for increased awareness and research to address the challenges faced by women dealing with this debilitating condition.

In the recent study, Dr. Marlena Fejzo and her colleagues at the University of Cambridge in England delved into measuring the hormone in the blood of pregnant women while analyzing the genetic factors contributing to hyperemesis.

Their findings revealed a significant link between higher GDF15 levels during pregnancy and women experiencing hyperemesis, in contrast to those without symptoms.

Interestingly, the impact of the hormone appears to be influenced by a woman's sensitivity and her exposure to GDF15 before pregnancy. For instance, women in Sri Lanka with a rare blood disorder, resulting in consistently elevated GDF15 levels, showed rare instances of nausea or vomiting during pregnancy.

Dr. Stephen O'Rahilly, an endocrinologist at the University of Cambridge leading the research, noted that this condition virtually eliminated pregnancy symptoms for these women, speculating that extended exposure to GDF15 before pregnancy might have a protective effect. This exposure could potentially make women less responsive to the sudden surge in the hormone triggered by the developing fetus.

To explore this further, the researchers conducted lab experiments involving mice. Mice exposed to a small amount of the hormone and later given a significantly larger dose three days later demonstrated reduced loss of appetite compared to animals not given the earlier dose, indicating a robust desensitization effect. These findings provide valuable insights into the complex relationship between GDF15, sensitivity, and pregnancy symptoms, paving the way for potential breakthroughs in managing hyperemesis.