Paternal smoking and childhood overweight: evidence from the Hong Kong "Children of 1997".
OBJECTIVE
This study examined, in a non-Western sociohistorical context, whether prenatal or postnatal secondhand smoke (SHS) exposure for children of nonsmoking mothers was associated with higher childhood BMI, and it clarified whether the observed associations were biologically mediated or socioeconomically confounded.


METHODS
A total of 6710 and 6519 children of nonsmoking mothers (N = 7924) with BMI data at approximately 7 and approximately 11 years, respectively, from a population-representative (N = 8327), Hong Kong Chinese birth cohort ("Children of 1997"), born in April or May 1997, were included in the analysis.


RESULTS
Compared with no SHS exposure, daily paternal smoking increased mean BMI z scores, but not height, at 7 years (difference: 0.10 [95% confidence interval: 0.02-0.19]) and at 11 years (difference: 0.16 [95% confidence interval: 0.07-0.26]), with adjustment for gender, birth order, socioeconomic position, mother's place of birth, breastfeeding, serious morbidity, and pubertal status.


CONCLUSIONS
Our findings, although preliminary, suggest that the association of paternal smoking with child overweight might be biologically mediated. Given the known harms of smoking, reducing SHS exposure from conception as a precautionary action for childhood overweight might be warranted.
Kwok
Man Ki
MK
University of Hong Kong, Li Ka Shing Faculty of Medicine, Department of Community Medicine and School of Public Health, Hong Kong, China.
Schooling
C Mary
CM
Lam
Tai Hing
TH
Leung
Gabriel M
GM
D017677:Age Distribution; D000886:Anthropometry; D015992:Body Mass Index; D015984:Causality; D002648:Child; D015331:Cohort Studies; D016001:Confidence Intervals; D005192:Family Health; D005260:Female; D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D016014:Linear Models; D008297:Male; D015999:Multivariate Analysis; D050177:Overweight / Q000453:epidemiology*; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000453:epidemiology*; D011446:Prospective Studies; D012307:Risk Factors; D017678:Sex Distribution; D012959:Socioeconomic Factors; D014028:Tobacco Smoke Pollution / Q000009:adverse effects / Q000706:statistics & numerical data*
D014028:Tobacco Smoke Pollution