Associations between maternal age in pregnancy and offspring blood pressure (BP) at age 7(1/2) were investigated in 7623 singletons from the Avon Longitudinal Study of Parents and Children (ALSPAC). In models adjusted for age and sex there was an inverse relationship between maternal age and BP in children: beta = -0.06 mmHg per year of maternal age (95% CI -0.10 to -0.01, P = 0.02) for systolic BP and beta = -0.04 (95% CI -0.07 to -0.01, P = 0.02) for diastolic BP. However, this association disappeared after adjustment for confounding factors: beta = -0.02 mmHg per year of maternal age (95% CI -0.07 to 0.04, P = 0.5) for systolic BP and beta = -0.03 (95% CI -0.07 to 0.01, P = 0.2) for diastolic BP. We conclude that there is no evidence of a relationship between maternal age in pregnancy and childhood BP in this contemporary birth cohort.