Potential Biological Mechanisms Underlying Susceptibility to Nausea and Vomiting of Pregnancy in Women with Polycystic Ovary Syndrome: A Narrative Review.

Polycystic ovary syndrome (PCOS) is a common endocrine disorder characterised by hormonal and metabolic disturbances that are often present before pregnancy. Emerging evidence suggests that women with PCOS may be more susceptible to nausea and vomiting of pregnancy (NVP), particularly moderate-to-severe symptoms, raising interest in the potential biological links between these conditions. This narrative review examines the endocrine and metabolic characteristics of PCOS during early pregnancy and synthesises the pathways potentially involved in NVP across five domains: neuroendocrine regulation, placental-derived factors, appetite and energy balance, gut microbiota-endocrine interactions, and androgen-related metabolic pathways. Overall, pre-existing endocrine and metabolic disturbances in PCOS may modify maternal adaptation to the physiological changes of early pregnancy, allowing these pathways to collectively influence susceptibility to and severity of NVP. Within this multidomain context, altered serotonergic regulation and growth differentiation factor 15 (GDF15)-related placental signalling may act as two parallel pathways involved in sensitisation and signal amplification and, together with the other pathways, influence the manifestations of NVP. Because the available evidence is largely indirect, these potential mechanisms require validation in translational and prospective clinical studies.