Maternal Smoking During Pregnancy and Offspring's Risk for Bone Fracture in Childhood and Adolescence

Abstract

Conditions during gestation, such as maternal smoking, may affect offspring's bone structure. This could increase the offspring's risk of bone fractures during childhood. In this study we aimed to assess the association between prenatal exposure to maternal smoking and childhood bone fracture risk. We used a register‐based birth cohort that included all children born in Finland between January 1987 – September 1990. After exclusions the final study population consisted of 220 699 persons. Using a unique national identification number, we linked the cohort data to the fracture diagnosis in specialty care and covariate data using the Medical Birth Register (MBR), Statistics Finland and Care Register for Health Care (CRHC). The fractures were analyzed in three groups: all fractures, non‐high energy fractures and high energy fractures. The analyses were adjusted for sex, parity, child's year of birth, mother's age at childbirth, mother's and father's educational level and mother's fracture status. We tested the association in three age groups: < 1 year, 1‐ < 5 years and 5‐ < 15 years using Cox and (recurrent fractures) Poisson regression. A total of 18 857 (8.5%) persons had at least one bone fracture diagnosis before the age of 15. In the age group 5‐ < 15 years, maternal smoking during pregnancy was associated with higher fracture risk in all of the studied fracture groups: HR 1.12 (95% Cl 1.06–1.17) in all fractures, 1.13 (95% Cl 1.07–1.19) in non‐high energy and 1.15 (95% Cl 1.00–1.32) in high energy fractures. There were no significant associations in other age groups in any of the fracture groups. No statistically significant association between maternal smoking during pregnancy and offspring's risk of recurrent fractures was found. In conclusion, 5‐ to 15‐year‐olds whose mothers have smoked during pregnancy have an increased risk of bone fractures treated in specialty care.This article is protected by copyright. All rights reserved.