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A new landmark study has revealed that women suffering from hyperemesis gravidarum (HG)—a severe form of nausea and vomiting during pregnancy—face a significantly increased risk of multiple serious mental health conditions. Published in The Lancet Obstetrics, Gynaecology, & Women’s Health in September 2025, this is the largest study to date exploring the broad neuropsychiatric impact of HG and highlights critical implications for maternal health care worldwide.
What is Hyperemesis Gravidarum?
HG affects approximately 3.6% of pregnancies globally and is the leading cause of hospitalization in the first trimester. Unlike common morning sickness, HG involves persistent and extreme nausea and vomiting that can trigger severe dehydration, weight loss, and nutritional deficiencies. Many women experience prolonged symptoms extending past the first trimester, leading to anxiety, social isolation, and difficulty managing daily life. Some women report considering pregnancy termination due to the physical and emotional toll of HG.
The Study and Key Findings
Researchers from King’s College London and the South London and Maudsley NHS Foundation Trust analyzed health records of 476,857 pregnant women diagnosed with HG from 135 healthcare providers across 18 countries. Using a retrospective cohort design with data from the TriNetX Global Collaborative Network, they examined 24 different neuropsychiatric and mental health outcomes occurring within a year of HG diagnosis.
The study found a more than 50% increased risk in 13 mental health conditions, including post-partum psychosis and post-traumatic stress disorder (PTSD). The risk of Wernicke’s encephalopathy—a neurological disorder caused by vitamin B1 deficiency—was doubled, as were risks for refeeding syndrome (a serious complication in malnourished patients), eating disorders, and depression. Notably, postpartum depression was 2.7 times more likely among women with HG.
Dr. Hamilton Morrin, a doctoral fellow at King’s College London, explained, “While many pregnant women have some nausea and vomiting, for women with hyperemesis gravidarum, the symptoms are profoundly disabling. This study confirms the increased risk of anxiety, depression, and PTSD seen in previous research and extends this understanding to include more severe mental health disorders such as psychosis and eating disorders. These conditions require urgent specialist care to protect the safety and well-being of mother and child.”
Mental Health Risk Independent of Physical Severity
Using the World Health Organization’s ICD-11 classification, HG is categorized into “mild HG” and “HG with metabolic disturbance” (characterized by electrolyte imbalance, dehydration, and carbohydrate depletion). Interestingly, women with metabolic disturbance tended to have a lower risk of depression than those with mild HG. This finding emphasizes that physical severity alone does not predict mental health risk, underscoring the need for comprehensive mental health screening and support for all women affected by HG, regardless of symptom severity.
Dr. Morrin noted, “The classification helps identify women who need treatment for physical complications but does not reliably identify those who need mental health support. We have a duty to ensure integrated physical and mental health care from early pregnancy through postpartum.”
Expert Perspectives and Clinical Implications
Senior author Dr. Thomas Pollak, consultant neuropsychiatrist at King’s College London, commented, “There has historically been a disconnect between how medical professionals view the mental health impact of HG and how women living with the condition describe their experience. Our study highlights this reality and calls for urgent recognition of the potential severity of psychiatric disorders linked to HG. Integrated care pathways involving obstetric, psychiatric, and nutritional services are crucial.”
Current treatment for HG involves antiemetic medications, intravenous fluids, and nutritional support, but addressing mental health is often neglected. Given the life-altering nature of HG and its association with serious psychological conditions—including risks of postpartum psychiatric disorders—healthcare providers should proactively monitor mental health and deliver psychological support alongside physical treatments.
Context and Background
Prior studies have shown increased anxiety and depression rates in women with HG, but most were limited by smaller sample sizes or narrower outcome focuses. This extensive multinational study now quantifies a broad spectrum of neuropsychiatric risks with robust statistical power, providing essential evidence to inform clinical guidelines.
Biological risk factors for HG include thyroid and parathyroid disease, type 1 diabetes, and prior pregnancy complications. Socioeconomic and ethnic disparities also influence risk. A 2024 study linked heightened sensitivity to the hormone GDF-15 as a potential cause of HG. Understanding these factors could pave the way for targeted therapies in the future.
Limitations and Future Directions
While the study’s retrospective design leverages real-world clinical data across diverse populations, it cannot establish causality definitively. Data on symptom duration, psychosocial variables, and treatment details were limited. Researchers call for prospective studies and clinical trials to better understand mechanisms driving mental health complications and test integrated treatments.
What This Means for Readers
Women experiencing severe nausea and vomiting during pregnancy should be aware that HG is a serious medical condition with possible mental health consequences. It is important to seek timely medical evaluation and comprehensive care that includes both physical symptom management and psychological support. Partners and caregivers should also recognize the emotional toll HG can impose.
Healthcare professionals are encouraged to routinely screen for anxiety, depression, PTSD, and other psychiatric conditions in patients with HG to ensure early intervention. Raising awareness and improving support services can reduce long-term impacts on maternal and infant health.
Medical Disclaimer: This article is for informational purposes only and should not be considered medical advice. Always consult with qualified healthcare professionals before making any health-related decisions or changes to your treatment plan. The information presented here is based on current research and expert opinions, which may evolve as new evidence emerges.
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