Background: Estimates of fertility for the overseas-born based on the period Total Fertility Rate (TFR) suggest that levels of childbearing are significantly higher among foreign-born women than women born in the UK. However, migration and timing of subsequent family formation mean that aggregate measures of fertility based on period TFRs may not be a useful indicator of the likely completed family size that migrant women will have at the end of their reproductive lives.

Objective: The paper quantifies childbearing according to duration since migration among female migrants to England and Wales arriving between 2001 and 2011, and examines how these patterns differ according to age at arrival and country of birth.

Methods: Data from the Office for National Statistics Longitudinal Study, a 1% sample of the population of England and Wales, are used to identify the reported date of arrival in the UK and to estimate childbearing prior to and subsequent to arrival.

Results: Fertility rates peak in the first one to four years subsequent to arrival among migrants from Pakistan and Bangladesh. Migrants from India and Poland show a delay in childbearing after migration to England and Wales, and lower fertility rates compared to migrants from Pakistan and Bangladesh, who show high fertility after migration at least for the first five years.

Conclusions: There are large differences in the timing of fertility among migrants according to age at arrival and migrant country of origin, which are likely to be related to the reason for migration. Tempo distortions among some migrant groups mean that the period TFR is not necessarily a useful summary measure of the likely lifetime fertility of migrant groups.