Ethnicity or environment: effects of migration on ovarian reserve among Bangladeshi women in the United Kingdom.

To assess whether the quality of early childhood environments among different groups of Bangladeshi women, including migrants to the United Kingdom (UK), contributes to variation in ovarian reserve and the rate of reproductive aging in later life.Cross-sectional study.London (UK) and Sylhet town, NE Bangladesh.A total of 179 healthy women volunteers aged 35-59 years were divided into four groups: [1] 36 Bangladeshis living in Sylhet, Bangladesh; [2] 53 Bangladeshis who migrated to the UK as adults; [3] 40 Bangladeshis who migrated to the UK as children aged 0-16 years; and [4] a reference group of 50 women of European origin living in London.None.Levels of serum antimüllerian hormone, inhibin B, FSH, and E2, and anthropometrics derived from biomarkers; reproductive, demographic, and health variables from structured questionnaires.Bangladeshi migrants who moved to the UK as children and European women had a highly significantly larger, age-related ovarian reserve compared with migrant Bangladeshis who had moved to the UK as adults or Bangladeshi women still living in Bangladesh. There were no other significant covariates in the model.The study points to the importance of childhood development in considering variation in ovarian reserve across different ethnic groups. Clinical studies and research in assisted reproductive technology have emphasized the role of genes or race in determining inter-population variation in ovarian reserve. Early life developmental factors should be given due consideration when evaluating inter-group differences in response to assisted reproductive technology.