1. Few studies have investigated associations of pregnancy physical activity with maternal and neonatal health markers in minority ethnic and economically disadvantaged groups of women, who are higher risk for pregnancy complications.

2. We found that mid-pregnancy physical activity was beneficially associated with maternal cardiometabolic health markers and neonatal adiposity in white British and Pakistani-origin women living in a deprived urban setting, without influencing gestational age or birth weight.

3. Associations were dose-dependent in white British women. In Pakistani-origin women (three-quarters of whom were inactive) even a small volume of physical activity in mid-pregnancy conferred some health benefit. This could be influential in helping to reduce health inequalities.