People that move home within developed countries report, on average, better health than non-movers. Pregnant women, new mothers and infants are particularly mobile, but the limited evidence regarding the relationship between their mobility and health suggests they may not conform to the 'healthy migrant' effect. This paper examines the relationship between mobility and health among these groups in the UK, using logistic regression to analyse cross-sectional data for 18,197 families in the Millennium Cohort Study wave one. It compares health status variables among mobile and non-mobile families; describes mobile families' socio-demographic characteristics; explores associations between health outcomes, reasons for residential moves, and experiences of homelessness; and assesses the association between mobility and health care utilisation, social support and residential satisfaction. The paper concludes that mobile pregnant women, new mothers and infants do have poor health outcomes in comparison to non-movers, but this is primarily explained by their socio-demographic characteristics and the negative circumstances associated with a minority of their moves. Families that moved during pregnancy and infancy had worse self-rated health and depression among mothers, and lower birth weight and higher risk of accidents among infants, than non-movers. Mothers in mobile families were younger and had lower levels of education and owner-occupation than non-movers. After adjustment for socio-demographic characteristics mobility was weakly and non-significantly associated with most health variables with the exception of self-rated health and depression among mothers who moved for negative reasons (such as relationship breakdown or problems with neighbours), or had been homeless since birth. After adjustment mobile families had lower levels of most measures of health care utilisation compared to non-movers, but mothers did not report less frequent social contacts, and those that moved during infancy for positive reasons (such as wanting a better home or neighbourhood) had greater satisfaction with home and area.