Association between maternal smoking during pregnancy and risk of bone fractures in offspring: a systematic review and meta-analysis

Abstract

This study aimed to investigate the effect of maternal smoking during pregnancy (MSDP) on the risk of bone fractures in the offspring through a systematic review and meta-analysis. The PubMed, Web of Science, and Scopus databases were systematically searched for relevant articles published through July 2019. According to heterogeneity, the pooled risk ratio (RR) and odds ratio (OR) and their corresponding 95% confidence interval (CI) were obtained using fixed or random effects models. The heterogeneity and quality of the included studies were assessed by the I-squared (I2 ) statistic and the Newcastle-Ottawa scale, respectively. Sensitivity analyses were performed to test the effect of MSDP misclassification on the results. The review of 842 search records yielded 5 studies including 8,746 mother-child pairs that were included in the meta-analysis. Pooling adjusted effect measures showed that MSDP was not associated with a later risk of bone fractures in the offspring (pooled RR, 1.15; 95% CI, 0.84-1.58; I2 =66.8%; P=0.049). After the adjustment for misclassification, MSDP may be associated with a 27% increased risk of bone fracture (pooled OR, 1.27; 95% CI, 1.00-1.62; I2 =0%; P=0.537). After the adjustment for misclassification, MSDP is associated with an increased risk of bone fractures among children whose mothers smoked during pregnancy.

Keywords: Bone fractures; Maternal smoking; Meta analyses; Misclassification; Pregnancy.

Fig. 1.

Preferred Reporting Items for Systematic Reviews and Meta-Analyses flow diagram of the study selection process for a systematic review and meta-analysis of the association between maternal smoking during pregnancy and the risk of fractures.

Fig. 2.

Forest plot of 4 studies showing the crude effect of maternal smoking during pregnancy on the risk of bone fractures in offspring through a fixed effect model. CI, confidence interval; D+L, DerSimonian and Laird; I-V, inverse variance; OR, odds ratio.

Fig. 3.

Forest plot of 3 studies showing the adjusted effect of maternal smoking during pregnancy on the risk of bone fractures in offspring through a random effects model. CI, confidence interval; D+L, DerSimonian and Laird; I-V, inverse variance; OR, odds ratio; RR: risk ratio.

Fig. 4.

Forest plot of 4 studies showing the crude effect of MSDP on the risk of bone fractures in offspring after the adjustment for MSDP misclassification through fixed-effect model: (A) deterministic sensitivity analysis; and (B) probabilistic sensitivity analysis. MSDP, maternal smoking during pregnancy; CI, confidence interval; D+L, DerSimonian and Laird; I-V, inverse variance; OR, odds ratio.