Abstract
OBJECTIVE Investigate the effect of exposure to smoking during pregnancy and early childhood on changes in the body mass index (BMI) from birth to adolescence.METHODS A population-based cohort of children (0-5 years old) from Cuiabá, Midwest Brazil, was assessed in 1999-2000 (n = 2,405). Between 2009 and 2011, the cohort was re-evaluated. Information about birth weight was obtained from medical records, and exposure to smoking during pregnancy and childhood was assessed at the first interview. Linear mixed effects models were used to estimate the association between exposure to maternal smoking during pregnancy and preschool age, and the body mass index of children at birth, childhood and adolescence.RESULTS Only 11.3% of the mothers reported smoking during pregnancy, but most of them (78.2%) also smoked during early childhood. Among mothers who smoked only during pregnancy (n = 59), 97.7% had smoked only in the first trimester. The changes in body mass index at birth and in childhood were similar for children exposed and those not exposed to maternal smoking. However, from childhood to adolescence the rate of change in the body mass index was higher among those exposed only during pregnancy than among those who were not exposed.CONCLUSIONS Exposure to smoking only during pregnancy, especially in the first trimester, seems to affect changes in the body mass index until adolescence, supporting guidelines that recommend women of childbearing age to stop smoking.
Highlights
The prevalence of overweight and obesity in childhood and adolescence is increasing mainly among low-middle income countries,[17] challenging health systems in areas of limited resources
Among 2,405 children evaluated in childhood (1999/2000), length and weight at birth was obtained from 99.5%; in preschool age the height and weight of all children were measured, and 71.4% of them were evaluated in adolescence (2009-2011) at ages between 10 and 17 years old
As previously reported,[21] loss to follow-up was higher among adolescents with low height-for-age at preschool age, mothers with lower education level and among those exposed to maternal smoking during pregnancy
Summary
The prevalence of overweight and obesity in childhood and adolescence is increasing mainly among low-middle income countries,[17] challenging health systems in areas of limited resources. Some studies, including systematic review and meta-analysis, report an association between maternal smoking during pregnancy and overweight in later life.[14,23] Studies confirmed a dose-dependence relationship between the number of cigarettes smoked during pregnancy and overweight[13,15] and independence of intrauterine growth restriction.[28] Most studies were performed in high-income countries and approached the effects of maternal smoking during pregnancy on the risk of overweight and adiposity in childhood, and the effects of these factors in adolescence have been reported.[2,13] The underlying mechanisms of this association are not well understood It is not clear how the period of exposure to maternal smoking affects the risk of obesity in offspring. Exposure after birth is highly correlated with prenatal exposure and appears to be associated with overweight in childhood.[9,18,24] few studies have considered the prenatal period in their analyses
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
