Association of maternal smoking during pregnancy with aerobic fitness of offspring in young adulthood: a prospective cohort study

Abstract

Objective: We evaluated the association of maternal pre-pregnancy body mass index (BMI), gestational weight gain (GWG), and maternal smoking with aerobic fitness in young men aged 19–20 years. Design: A 19–year prospective cohort study. Setting: Data from the Northern Finland Birth Cohort 1986 (NFBC 1986) and the Sodankylä Jaeger Brigade, Finland, in 2005–6. Population: Mothers and the 508 offspring in the NFBC 1986 who entered military service at the Sodankylä Jaeger Brigade in 2005. Methods: Associations of weight, 12–minute running test (Cooper test), and muscle fitness index (MFI) of offspring on entry to military service were evaluated with antenatal factors, including maternal smoking, pre-pregnancy BMI, and GWG. Main outcome measures: Aerobic and muscle fitness of the offspring were evaluated by the Cooper test and MFI. Results: Maternal smoking during pregnancy was associated with lower aerobic fitness of male adolescents, measured by the Cooper test (2356 m; 95% confidence interval, 95% CI 2265–2446 m), compared with the offspring of mothers who did not smoke during pregnancy (2537 m, 95% CI 2499–2574 m). This association was independent of the BMIs of both the mother and the offspring, GWG, and the smoking and physical activity of offspring (regression coefficient −140.6 m, 95% CI −273.1 to −8.0 m). High maternal pre-pregnancy BMI and excessive GWG were also associated with lower aerobic fitness of the offspring; however, this association was mediated via the weight of the offspring. Conclusions: Maternal smoking during pregnancy may have a negative impact on the aerobic fitness of the offspring. Tweetable abstract: Study shows that young men have lower aerobic fitness if their mothers smoked during pregnancy.