Morning sickness: We finally know what causes nausea and vomiting during pregnancy

An excess level of a hormone called GDF15 is the main cause of pregnancy sickness, including the most severe cases, known as hyperemesis gravidarum. The evidence for this has been growing for the past few years and now a study combining multiple lines of evidence should settle the issue.

Crucially, the study also shows that women’s sensitivity to GDF15 depends on how much their bodies produce prior to pregnancy. The findings suggest that if those known to have a high risk …