The large-scale study, published in The Lancet Obstetrics, Gynaecology, & Women's Health, analysed medical records of 476,857 pregnant women in the UK. Researchers examined 24 neuropsychiatric and mental health outcomes reported within a year of HG diagnosis, uncovering striking associations between the condition and long-term psychological health. What is Hyperemesis Gravidarum? HG affects up to 3.6 per cent of pregnancies and is the most common reason for hospitalisation in the first trimester. Unlike the more common "morning sickness," HG involves persistent and severe nausea and vomiting, often leading to dehydration, significant weight loss, and electrolyte imbalance. While most cases resolve in the second trimester, the toll on women's physical and emotional well-being can be severe. Key findings Previous studies had linked HG to anxiety, depression, and PTSD. However, this new research highlights a broader and more serious spectrum of risks: • A 50% increased risk across 13 mental health conditions. • Double the risk of Wernicke's encephalopathy, a neurological condition caused by vitamin B1 deficiency. • Higher likelihood of eating disorders and refeeding syndrome, a complication from reintroducing food after malnutrition. • 2.7 times higher risk of postpartum depression, making it one of the most alarming outcomes. "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," said Dr Hamilton Morrin, Doctoral Fellow at the Institute of Psychiatry, Psychology and Neuroscience, King's College London. "These conditions warrant urgent referral to specialist services for timely assessment and treatment to ensure the safety of both mother and child." Rethinking severity The World Health Organisation's ICD-11 classification subcategorises HG into "mild HG" and "HG with metabolic disturbance," the latter marked by carbohydrate depletion, dehydration, or electrolyte imbalance. Surprisingly, the study revealed that women with metabolic disturbance had a lower risk of depression compared to those with milder HG. This counterintuitive finding suggests that the perception of severity does not always match psychological outcomes. Experts believe that women with seemingly "mild" HG may not receive adequate medical or emotional support, leaving them more vulnerable to mental health struggles. The study underscores the urgent need for comprehensive mental health screening and intervention for all women diagnosed with HG, not just those with severe physical symptoms. With growing awareness of maternal mental health, researchers stress that HG should be recognised not only as a physical condition but also as a major risk factor for psychiatric illness. As Dr Morrin emphasised, early detection and multidisciplinary care could help mitigate risks, ensuring that women battling this debilitating condition receive the support they deserve.