For many women, nausea and vomiting are common symptoms in early pregnancy. But for some, these symptoms become so extreme that they develop a condition called hyperemesis gravidarum (HG).
Unlike typical morning sickness, HG causes constant and severe nausea and vomiting that can lead to dehydration, weight loss, and hospital stays.
Now, the largest study of its kind has shown that HG not only affects physical health but also greatly increases the risk of mental health problems.
The research, published in The Lancet Obstetrics, Gynaecology, & Women’s Health, analyzed the medical records of nearly 477,000 pregnant women worldwide who were diagnosed with HG.
The study included data from 135 health care providers in 18 countries, making it the first global investigation of the link between HG and mental health.
HG affects up to 3.6% of pregnancies and is the leading cause of hospitalization in the first trimester.
While symptoms usually improve by the second trimester, the impact can be devastating.
Women with HG often report feeling isolated, anxious, and uncertain about continuing their pregnancies. More than half say they have considered termination because of the severity of their symptoms.
In this new study, researchers examined 24 different neuropsychiatric and mental health outcomes within one year of an HG diagnosis. They found that women with HG had more than a 50% increased risk of 13 conditions, including post-traumatic stress disorder and postpartum psychosis.
Some conditions, like depression and postpartum depression, were almost three times more likely.
The risks were even higher for serious complications such as Wernicke’s encephalopathy, a neurological disorder caused by vitamin B1 deficiency, and refeeding syndrome, which occurs when food is reintroduced too quickly after malnutrition.
Dr. Hamilton Morrin of King’s College London emphasized that HG is far from normal pregnancy sickness.
“It can be profoundly debilitating,” he said. “Our study shows that HG increases the risk not only of anxiety and depression but also severe conditions like psychosis and eating disorders.” He added that many of these problems require urgent referral to specialist services to protect both mother and baby.
The study also looked at whether the severity of HG, categorized by the World Health Organization as “mild” or “with metabolic disturbance,” was linked to mental health outcomes. Surprisingly, women with the more physically severe form did not always have worse mental health risks than those with mild HG.
This means that even when HG is not life-threatening physically, its psychological toll can still be extreme.
Senior author Dr. Thomas Pollak noted that the medical community has often underestimated the mental health impact of HG.
“Our findings show that this gap is real and can be very serious,” he said. “HG can lead to severe psychiatric disorders, and care must address both physical and mental health from the very start of pregnancy.”
