A study published on Wednesday in the journal Nature reveals that the primary cause of nausea and vomiting in the first trimester of pregnancy is attributed to a single hormone, marking a potential breakthrough for better treatments of morning sickness, including severe cases.
The research, which confirms earlier findings, identifies the hormone GDF15 as pivotal.
The study indicates that the levels of this hormone circulating in a woman’s blood during pregnancy, as well as her exposure to it before conception, dictate the severity of her symptoms.
Nausea and vomiting affect more than two-thirds of pregnant women during the first trimester. Approximately 2 percent experience hyperemesis gravidarum, a condition characterized by persistent vomiting and nausea throughout pregnancy.
This severe form can lead to malnutrition, weight loss, and dehydration, posing risks of preterm birth, pre-eclampsia, and blood clots for both the mother and the fetus.
Dr. Marlena Fejzo, a geneticist at the University of Southern California Keck School of Medicine and co-author of the study, emphasized the historical dismissal of hyperemesis as psychological despite its severity.
She recounted her personal struggle with the condition during her second pregnancy in 1999, where she faced skepticism from her doctor until hospitalization and miscarriage occurred.
Dr. Fejzo’s persistence led to collaboration with 23andMe, which included hyperemesis-related questions in customer surveys, revealing genetic links to GDF15 variants in affected individuals.
GDF15, triggered by stress such as infection, targets specific receptors in the brain responsible for nausea and vomiting.
The study, conducted in partnership with the University of Cambridge, measured GDF15 levels in pregnant women and analyzed genetic factors contributing to hyperemesis.
The findings indicated significantly higher GDF15 levels in women with hyperemesis compared to those without symptoms.
Interestingly, women in Sri Lanka with a rare blood disorder characterized by chronically increased GDF15 levels rarely experienced pregnancy-related nausea and vomiting.
Dr. Stephen O’Rahilly, an endocrinologist at Cambridge who led the study, suggested that prior exposure to GDF15 might desensitize women, reducing their sensitivity to the hormone’s surge during pregnancy.
In lab experiments with mice, those previously exposed to GDF15 showed less appetite suppression upon subsequent exposure, indicating a potential desensitizing effect.
The study raises optimism for improved hyperemesis treatments. Future medications could potentially block GDF15’s brain effects in affected patients, pending safe outcomes from pregnancy-specific clinical trials.
Similar drugs are already undergoing trials for cancer patients experiencing appetite loss and vomiting linked to GDF15.
Moreover, there’s potential to prevent hyperemesis. Women at risk, identified through severe symptoms in prior pregnancies, might benefit from low-dose pre-pregnancy exposure to GDF15.
Metformin, a diabetes drug already in use to enhance fertility, increases GDF15 levels and could play a role in preventive strategies.
Dr. Rachel Freathy, a geneticist at the University of Exeter not involved in the study, underscored the significance of establishing a genetic link between GDF15 and hyperemesis, advocating for greater recognition of the condition.
She noted that understanding the biological basis could shift perceptions away from dismissing the condition as psychological, validating women’s experiences.
The study’s genetic insights into GDF15 represent a significant step towards advancing treatments and understanding of hyperemesis gravidarum, potentially transforming care for pregnant women worldwide.
