Maternal socioeconomic and physical activity level in pregnancy is associated with offspring's sport-related physical activity at age 14 years in a Danish prospective cohort study.

Regular physical activity (PA) protects against several non-communicable diseases. However, there is social inequality in PA and low adherence to PA recommendations. We investigated whether maternal socioeconomic status (SES) and PA in pregnancy are associated with sport-related PA level in 14-year-old offspring. Self-reported PA from 23 753 mother-child dyads in the Danish National Birth Cohort was retrieved from pregnancy and 14-year-old offspring. Weekly hours of PA were dichotomized into fulfilling official recommendations of 30 min/day for adults and 60 min/day for children or not. Information on maternal educational level was categorized into high, medium high, medium low, and low SES. Logistic regressions were applied to evaluate associations between maternal SES and adherence to PA recommendations and offspring adherence to PA recommendations at age 14. Most women did not fulfil PA recommendations in pregnancy (93%). In offspring, this was 79%. There were higher odds of the offspring not fulfilling PA recommendations at age 14 with low vs high maternal SES [adjusted odds ratio (OR): 1.42, 95% confidence interval (CI): 1.28, 1.59] and when mothers did not adhere to PA recommendations during pregnancy (adjusted OR: 1.33, 95% CI: 1.18, 1.49), independently of each other; and more pronounced in girls than in boys. This large prospective cohort study supports findings that socioeconomic background and maternal behaviours in early life may influence the offspring's behaviour, including sport-related PA, in later life. Increasing engagement in PA during pregnancy may not only be beneficial for maternal health but also later offspring health and behaviour.