Objective Studies of secondhand smoke (SHS) exposure especially childhood SHS exposure and pregnancy loss are limited. We used baseline data of the Guangzhou Biobank Cohort Study (GBCS) to examine the association of childhood SHS exposure with a history of pregnancy loss.
Methods Never smoking women aged 50 years or above in GBCS from 2003 to 2008 were included. Propensity score matching (PSM) was used to control for confounding. Negative binomial regression and logistic regression were used to examine the association of childhood SHS, assessed by number of smokers in childhood household and frequency of exposure, with past pregnancy loss.
Results Of 19 562 women, 56.7% (11 096) had SHS exposure during childhood. In negative binomial regression, after adjusting for age, education, past occupational dust exposure, past home fuel exposure, oral contraceptive, adulthood SHS exposure, age at first pregnancy and age at first menarche, compared to non-exposure, the incidence rate ratio of one more pregnancy loss was 1.20 (95% CI1.05 to 1.37) in those who lived with ≥2 smokers in the same household, and 1.14 (95% CI 1.04 to 1.25) in those exposed ≥5 times/week. After similar adjustment, logistic regression showed that the OR of pregnancy loss ≥2 times (versus 0 to 1 time) was 1.25 (95% CI 1.00 to 1.57) and 1.20 (95% CI 1.03 to 1.40) for high density (≥2 smokers in the same household) and frequency (≥5 times/week) of childhood exposure, respectively.
Conclusions Childhood SHS exposure was associated with higher risks of pregnancy loss in middle-aged and older Chinese women.
- Secondhand smoke
- Low/Middle income country
- Priority/special populations
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SY and LX contributed equally.
Contributors SY, LX and YH contributed to data analysis and manuscript writing. CJ, KKC, YJ and WZ contributed to study design and data collection. THL contributed to study design, manuscript revision and approval of the final submission. All authors contributed to the drafting and editing of this manuscript and approved the final version submitted for publication.
Funding This study was supported by research grants from the Guangdong Natural Science Foundation of China, Guangdong, China (Grant number: 9451062001003477), the Guangzhou Science and Information Bureau, Guangzhou, China (2012J5100041), the National Natural Science Foundation of China (81373080) and the Beijing Municipal Science and Technology Commission (Z121107001012070).
Competing interests None declared.
Patient consent Obtained.
Ethics approval The study has ethics approval from the Guangzhou Medical Ethics Committee of the Chinese Medical Association, Guangzhou, China.
Provenance and peer review Not commissioned; externally peer reviewed.
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