Severe pregnancy sickness raises risk of mental health conditions by over 50%, study finds

The largest study on pregnant women with excessive nausea and vomiting (hyperemesis gravidarum) has identified increased risks of numerous neuropsychiatric and mental health outcomes. The study is published in the journal The Lancet Obstetrics, Gynaecology, & Women’s Health.

Researchers from King’s College London and South London and Maudsley NHS Foundation Trust conducted a study involving 476,857 pregnant women diagnosed with hyperemesis gravidarum (HG) from 135 health care providers worldwide. The study is the first to explore an array of neuropsychiatric and mental health outcomes for women with HG.

They performed a retrospective cohort study using the TriNetX Global Collaborative Network, a network collecting anonymized electronic health care record data from 18 different countries.

HG affects up to 3.6% of all pregnancies. HG is the most common cause of hospitalization in the first trimester of pregnancy, and the majority of HG cases (but not all) resolve from the second trimester.

Women with HG experience prolonged and severe nausea and vomiting, leading to dehydration and weight loss. Women may feel anxious about leaving home, isolated, and unsure that they will be able to cope with the rest of the pregnancy. Individuals with HG have reported various mental health challenges such as anxiety and depression, with over half of women considering termination of pregnancy.

Maternal risk factors for HG vary greatly from biological (thyroid and parathyroid disease, type 1 diabetes, or histories of past pregnancies) to socioeconomic deprivation and ethnicity. In addition, a study identified that sensitivity to a hormone called GDF-15 may be a driver for the disorder.

In this study, researchers looked at 24 neuropsychiatric and mental health-related outcomes reported within a year of diagnosis.

They found over 50% increased risk in 13 conditions, including post-partum psychosis and post-traumatic stress disorder. The risks were doubled for Wernicke’s encephalopathy (neurological condition due to vitamin B1 deficiency), refeeding syndrome (complications arising when food is introduced too quickly to someone who has been malnourished), eating disorders, and depression, particularly post-partum depression, which was 2.7 times more likely.

Dr. Hamilton Morrin, Doctoral Fellow at the Institute of Psychiatry, Psychology and Neuroscience at King’s College London, said, “Many pregnant women experience nausea and vomiting but for women with HG, this occurs at a level which is far from ‘normal’ and, as such, it can be profoundly debilitating.

“While we already knew from previous research that women with HG are at an increased risk of anxiety, depression and PTSD, our study not only confirmed these findings, but also demonstrated an increased risk of severe mental health conditions, including psychosis and eating disorders, as well as increased risk of Wernicke’s encephalopathy, a serious neuropsychiatric disorder where a deficiency of the vitamin thiamine leads to problems with memory and coordination.

“Many of these conditions would warrant urgent referral to specialist services for urgent assessment and treatment to ensure the safety of mother and child.”

In the ICD-11, the latest International Classification of Diseases by the World Health Organization, HG is subcategorized into “mild HG” and “HG with metabolic disturbance.”

The latter is characterized by carbohydrate depletion, dehydration, or electrolyte imbalance. The researchers also looked at whether this categorization is correlated with mental health outcomes.

Importantly, cases of HG with metabolic disturbance (perceived as more severe) showed a significantly reduced risk of depression compared to mild HG. This finding highlights the importance of adequate mental health screening and support for all women with HG, regardless of perceived severity.

“What we found is that the internationally recognized categorization of HG based on metabolic disturbance works well to identify individuals who require treatment for their physical health but may not always be suitable for identifying those in need of mental health support. The severity of HG does not directly correlate with the degree of impact on mental health, and as clinicians, we have a responsibility to ensure these women receive adequate integrated care across both physical and mental health,” said Dr. Hamilton Morrin.

Dr. Thomas Pollak, Clinical Reader and Consultant Neuropsychiatrist at King’s College London and the senior author of the study, added, “Until recently, there has been something of a disconnect between how the medical community has regarded the mental health impact of HG and how women themselves describe their experience.

“Our findings show that this gap is not only real but can be very serious. HG can be associated with severe psychiatric disorders that require urgent recognition and joined-up physical and mental health care from the very start of pregnancy.”