Polyendocrine metabolic ovarian syndrome in pregnancy: pathophysiology and outcomes.

Polyendocrine metabolic ovarian syndrome (PMOS), formerly known as polycystic ovary syndrome, is a chronic condition driven by genetic, epigenetic and lifestyle factors. The resulting endocrine changes, including hyperinsulinaemia and hyperandrogenism, underpin the clinical manifestations of PMOS and are amplified by overweight and obesity. Reproductive features of PMOS, including ovulatory disturbance, endometrial abnormalities, subfertility and an increased rate of pregnancy and birth complications, have long been documented in these patients, but awareness in clinical practice has only increased in the past decade. The pathophysiology of PMOS interacts with physiological changes in pregnancy, leading to pregnancy and birth complications, exacerbated by the high prevalence of pre-pregnancy overweight, obesity and increased gestational weight gain in PMOS. However, the condition is poorly recognized as an independent risk factor for pregnancy and birth complications in antenatal guidelines and clinical practice. The 2023 international evidence-based guidelines, supported by extensive meta-analyses, have advanced knowledge on PMOS and pregnancy and birth outcomes. They recommend recognition of 'higher-risk' status for individuals with PMOS in pregnancy and aim to improve antenatal prevention, awareness, screening and treatment. Here, we explore the pathophysiology of PMOS and PMOS during pregnancy as well as related pregnancy and birth complications. We also outline current guideline recommendations, implementation strategies and research priorities related to PMOS in pregnancy.