Does breastfeeding protect against childhood overweight? Hong Kong's 'Children of 1997' birth cohort.

BACKGROUND

Observational studies from mainly Western settings suggest breastfeeding may protect against childhood adiposity; however, breastfeeding and adiposity share social patterning potentially generating confounding, making evidence from other settings valuable.

METHODS

We used multivariable linear regression to examine the prospective adjusted associations of breastfeeding with body mass index (BMI), height and weight z-scores at 7 years of age relative to the 2007 World Health Organization (WHO) growth reference, in a large (n = 8327), population-representative Hong Kong Chinese birth cohort, recruited between April and May 1997 with high follow-up (n = 7026).

RESULTS

Low socio-economic position (SEP) was associated with never breastfeeding and with exclusive breastfeeding for > or =3 months. We did not find any association between breastfeeding and BMI [z-score mean difference 0.07, 95% confidence interval (CI) -0.05 to 0.19], height (0.02, 95% CI -0.07 to 0.11) or weight (0.07, 95% CI -0.05 to 0.18), adjusted for sex, birth weight, gestational age, SEP, second-hand smoke (SHS) exposure, parity, mother's age at birth, mother's place of birth and serious infant morbidity.

CONCLUSIONS

In a non-European setting, breastfeeding was not associated with child adiposity, suggesting that observed protective effects may be due to socially patterned confounding by SEP, maternal adiposity and maternal smoking.