Fig 2.

Maternal smoking during pregnancy and risk of fractures in offspring by attained age. Hazard ratios (95% confidence intervals) for fractures comparing offspring exposed to maternal smoking during pregnancy (any, 1-9 cigarettes/day, ≥10 cigarettes/day) with those unexposed (reference group). Hazard ratios are presented by attained age (0 to <1 year, 1 to <5 years, 5 to <15 years, ≥15 years) and for the different analysis models: model 1: whole cohort analysis adjusted for birth year; model 2: whole cohort analysis adjusted for birth year, sex of offspring, maternal age, parity, height, body mass index, parental education, occupation, and marital status; and model 3: within-sibship analysis including all covariates included in model 2 except for maternal height, a variable which is unlikely to vary among siblings in the same family