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Monday, March 5th., 2018

INMA: "Child overweight related to passive and active tobacco smoke"

The prevalence of childhood obesity has increased worldwide during the past few decades. Smoking during pregnancy has already been associated with childhood obesity in several studies, however, is the relationship with secondhand (passive) exposure to tobacco smoke during pregnancy or child passive exposure to tobacco smoke during childhood known as well?

Previous studies, which assessed the effect of partner smoking during pregnancy found a positive association with child body mass index (BMI). Nevertheless, there is disagreement regarding whether this is an altered effect because of familial factors, biological ones, or a combination of both. Furthermore, only a few studies have assessed direct measures of maternal prenatal passive smoke exposure, through questionnaires or biomarkers, in association with weight status, and results were inconsistent.

That is why a study was made to study the effect of maternal active and passive smoke exposure during pregnancy and child passive smoke exposure during childhood on child weight status. Until now no previous study had used biomarker measurements in children to strengthen exposure classification.

This study was made with the Asturias, Gipuzkoa, Sabadell and Valencia INMA cohorts, established between 2003 and 2008, and followed up until 4 years of age (1927 mothers and children in total), alongside with the older Menorca subcohort, established between 1997 and 1998 and followed up until 14 years of age (427 mothers and children in total). Tobacco exposure was assessed by questionnaires and confirmed by cotinine measurement in urine, along with extensive information on lifestyle and demographic factors.

Results indicate that both passive and active maternal exposures to tobacco smoke are associated to child BMI and overweight. A greater association was found in Menorca compared to the other cohorts (Asturias, Gipuzkoa, Sabadell and Valencia)s; in addition, in Menorca an association was observed between children’s passive smoke exposure and child BMI. These findings can be explained by the greater number of mothers that actively smoked in this subcohort, or by the fact that the relationship may only become apparent at later ages.

The association was independent of lifestyle factors, strengthening the possibility, supported by growing epidemiological and toxicological evidence, that tobacco smoke exposure contributes to childhood overweight.

REFERENCE: Robinson O, Martínez D, Aurrekoetxea JJ, Estarlich M, Somoano AF, Íñiguez C, Santa-Marina L, Tardón A, Torrent M, Sunyer J, Valvi D, Vrijheid M. The association between passive and active tobacco smoke exposure and child weight status among Spanish children. Obesity (Silver Spring). 2016 Aug;24(8):1767-77.