How Exposure to Environmental Tobacco Smoke, Outdoor Air Pollutants, and Increased Pollen Burdens Influences the Incidence of Asthma-0

<p><b>Copyright information:</b></p><p>Taken from "How Exposure to Environmental Tobacco Smoke, Outdoor Air Pollutants, and Increased Pollen Burdens Influences the Incidence of Asthma"</p><p>Environmental Health Perspectives 2006;114(4):627-633.</p><p>Published online 26 Jan 2006</p><p>PMCID:PMC1440792.</p><p>This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original DOI.</p

A Study on Mediation by Offspring BMI in the Association between Maternal Obesity and Child Respiratory Outcomes in the Amsterdam Born and Their Development Study Cohort

<div><p>Background</p><p>A causal relationship between maternal obesity and offspring asthma is hypothesized to begin during early development, but no underlying mechanism for the found association is identified. We quantitatively examined mediation by offspring body mass index (BMI) in the association of maternal pre-pregnancy BMI on risk of asthma and wheezing during the first 7–8 years of life in a large Amsterdam born birth cohort.</p><p>Methods</p><p>For 3185 mother-child pairs, mothers reported maternal pre-pregnancy BMI and offspring outcomes “ever being diagnosed with asthma” and “wheezing in the past 12 months” on questionnaires. We measured offspring height and weight at age 5–6 years. We performed a multivariate log linear regression comparing outcomes in offspring of mothers with different BMI categories. For each category we quantified and tested mediation by offspring BMI and also investigated interaction by parental asthma.</p><p>Results</p><p>At the age of 7–8 years, 8% of the offspring ever had asthma and 7% had current wheezing. Maternal pre-pregnancy obesity was associated with higher risks of asthma (adjusted RR 2.32 (95% CI: 1.49–3.61) and wheezing (adjusted RR 2.16 (95% CI: 1.28–3.64). Offspring BMI was a mediator in the association between maternal BMI and offspring wheezing, but not for asthma. There was no interaction by parental asthma.</p><p>Conclusions</p><p>Maternal pre-pregnancy obesity was associated with higher risks of offspring asthma and wheezing. The association between maternal obesity and offspring wheezing was both direct and indirect (mediated) through the child’s own BMI.</p></div

Illustration of sample size.

<p>LRTIs- lower respiratory tract infections. ^aSome versions of questionnaires did not ask about frequency/number of LRTIs. </p

Indirect effect of pre-pregnancy BMI on current wheezing at age 7–8 years through offspring BMI z-score at age 5 years (n = 1781).

<p>Adjusted for: maternal age, parental asthma, ethnicity, maternal education. A-path: a-coefficient describing the change in offspring’s zBMI per BMI category in comparison to normal maternal BMI. B-path: b-coefficient describing change in offspring current wheezing risk per 1 point change in offspring zBMI when maternal BMI is constant. C’(C)-path: direct (total) effect.</p

study outline.

<p>study outline.</p

Indirect effect of pre-pregnancy BMI on ever asthma at age 7–8 years through offspring BMI z-score at age 5 years (n = 1787).

<p>Adjusted for: maternal age, parental asthma, ethnicity, maternal education, A-path: a-coefficient describing the change in offspring’s zBMI per BMI category in comparison to normal maternal BMI. B-path: b-coefficient describing change in offspring asthma risk per 1 point change in offspring zBMI when maternal BMI is constant. C’(C)-path: direct (total) effect.</p

Differences in demographics (mean or prevalence), as a function of prepregnancy BMI in mothers and their offspring (n = 3185) ^{^}.

<p>^{^} Mother-child pairs of life-singleton births with returned pregnancy-questionnaires, including maternal weight and height, and a response at 7 years. BMI: body mass index.</p><p>* p-value calculated with chi-square test, ttest or Mann-Whitney U test.</p><p>Differences in demographics (mean or prevalence), as a function of prepregnancy BMI in mothers and their offspring (n = 3185) <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0140641#t001fn001" target="_blank">^{^}</a>.</p

Breathing patterns (mean (SD)) measured by respiratory inductance plethysmography.

<p>N = 18 for obese, one subject’s data was not recorded.</p

Sputum PMNs (concentration and %of recovered cells) and Sputum IL-6 concentration (pg/ml).

<p>Sputum PMNs (concentration and %of recovered cells) and Sputum IL-6 concentration (pg/ml).</p

Mean (SD) decrements in lung function variables (delta % fall) expressed as ((Pre-Post Ozone)/Pre Ozone)–(Pre-Post Air)/Pre Air)) X 100.

<p>Mean (SD) decrements in lung function variables (delta % fall) expressed as ((Pre-Post Ozone)/Pre Ozone)–(Pre-Post Air)/Pre Air)) X 100.</p