Long-term adverse influence of smoking during pregnancy on height and body size of offspring at ten years old in the UK Biobank cohort.

BACKGROUND

To explore the long-term relationship between maternal smoking during pregnancy and early childhood growth in the UK Biobank cohort.

METHODS

To estimate the effect of maternal smoking during pregnancy on offspring height and body size at ten years old, we performed binary logistic analyses and reported odds ratios (OR) as well as 95% confidence intervals (95%CIs). We also implemented the cross-contextual comparison study to examine whether such influence could be repeatedly observed among three different ethnicities in the UK Biobank cohort ( = 22,140 for White,  = 7094 for South Asian, and  = 5000 for Black). In particular, we conducted the sibling cohort study in White sibling cohort ( = 9953 for height and  = 7239 for body size) to control for unmeasured familial confounders.

RESULTS

We discovered that children whose mothers smoked during pregnancy had greater risk of being shorter or plumper at age ten in the full UK Biobank White cohort, with 15.3% (95% CIs: 13.0%∼17.7%) higher risk for height and 32.4% (95%CIs: 29.5%∼35.4%) larger risk for body size. Similar associations were identified in the South Asian and Black ethnicities. These associations were robust and remained significant in the White sibling cohort (12.6% [95%CIs: 5.0%∼20.3%] for height and 36.1% [95%CIs: 26.3%∼45.9%] for body size) after controlling for family factors.

CONCLUSION

This study robustly confirms that maternal smoking during pregnancy can promote height deficit and obesity for offspring at ten years old. Our findings strongly encourage mothers to quit smoking during pregnancy for improving growth and development of offspring.