Objectives: Over a quarter of UK births are to women who were born outside of the UK. Black and Minority Ethnic (BME) women are disproportionately affected by poor mental health and inequitable access to mental health care in the perinatal period, yet the influence of the migrant status (mothers' UK vs. non-UK birth) is poorly understood. This study aimed to explore the relationship between ethnicity, migration and mental health indicators among mothers participating in a large nationally representative cohort study. Study design: This is a secondary analysis of data from the Millennium Cohort Study. Methods: Logistic regression quantified the crude and adjusted effects of self-reported ethnicity and migrant status on prevalence of psychological distress and treatment for anxiety/depression at 9-month and 5-year postpartum. Results: We found substantial variation in the prevalence of distress according to ethnicity and migrant status, with Indian and Pakistani women at greatest risk. Despite equal or greater risk, BME and migrant women were less likely to report treatment for anxiety/depression. Mutually adjusted analyses showed ethnicity to be a stronger predictor of both outcomes than migrant status; however, at 5 years, being a migrant independently predicted lower odds of treatment, for a statistically similar level of distress. Conclusions: Migrant women are likely to be at high risk of poor mental health in the perinatal period and beyond, yet may face significant barriers to accessing mental health care. A better understanding of ethnicity and migration as interrelated risk factors for perinatal mental ill-health is needed to help National Health Service organisations develop policy and practice that is flexible and responsive to diversity. © 2019 The Royal Society for Public Health

Migration Mental health Ethnicity Mothers Postnatal

anxiety Pakistani clinical outcome depression anxiety disorder mental health service health care policy Indian minority group mental health human Self Report Cohort Studies perinatal period Ethnic Groups statistics and numerical data ethnic group controlled study Mental Health Services ethnology health care practice Mental Disorders mental disease evidence based practice Humans psychology Black person African Continental Ancestry Group Minority Groups female risk factor Risk Factors pregnancy Mothers health services prevalence Article health care major clinical study mother adult migration patient participation United Kingdom distress syndrome cohort analysis ethnicity Transients and Migrants high risk patient postnatal depression Postpartum Period puerperium Health Services Accessibility womens health health care delivery