Effects of Residential Indoor Air Quality and Household Ventilation on Preterm Birth and Term Low Birth Weight in Los Angeles County,California

Objectives. The purpose of our study was to examine the effects of indoor residential air quality on preterm birth and term low birth weight (LBW).Methods. We evaluated 1761 nonsmoking women from a case-control survey of mothers who delivered a baby in 2003 in Los Angeles County, California. In multinomial logistic regression models adjusted for maternal age, education, race/ethnicity, parity and birthplace, we evaluated the effects of living with smokers or using personal or household products that may contain volatile organic compounds and examined the influence of household ventilation.Results. Compared with unexposed mothers, women exposed to secondhand smoke (SHS) at home had increased odds of term LBW (adjusted odds ratio [OR] = 1.36; 95% confidence interval [CI] =  0.85, 2.18) and preterm birth (adjusted OR = 1.27; 95% CI = 0.95, 1.70), although 95% CIs included the null. No increase in risk was observed for SHS-exposed mothers reporting moderate or high window ventilation. Associations were also observed for product usage, but only for women reporting low or no window ventilation.Conclusions. Residential window ventilation may mitigate the effects of indoor air pollution among pregnant women in Los Angeles County, California.Although numerous studies have examined the effects of outdoor air pollution on birth outcomes, less information is available on the effects of residential indoor air quality in high resource countries, even though pregnant women spend on average more than 15 hours per day at or near their home, and 7 hours per day at work or other indoor locations.1,2 Indoor air quality is influenced not only by the intrusion of outdoor pollutants, but also by the indoor sources such as tobacco smoke, and off-gassing of chemical agents from personal and household products or furniture may also be important contributors.3 Although studies have reported increased risk of preterm birth and low birth weight (LBW) with maternal smoking and secondhand smoke (SHS) exposures,4–10 no pregnancy outcome study to date has evaluated the effects of other agents affecting indoor air quality in high resource countries, nor the potential protective effect of home ventilation. The majority of pregnancy outcome studies addressing indoor air pollution beyond SHS were conducted in occupational settings,11–18 or in low or medium resource countries focusing on smoke from biomass fuels.19–23Volatile organic compounds (VOCs) are present in organic solvents used in many personal products, cleaners, adhesives, and residential-use insecticides.3,24–26 Most epidemiologic studies of organic solvents examined only occupational exposures, and reported increased risks of spontaneous abortion, small for gestational age (SGA), preterm birth, birth defects, and reductions in birth weight.11–15,17,18,27,28 Only 2 studies in high resource countries examined residential indoor air exposures from VOC-emitting household products, and neither examined whether ventilation mitigated the effects of exposure.29,30In this study, we describe how SHS, personal and household product usage, as well as household ventilation together influence the risk of preterm birth and term LBW for women in Los Angeles County, California.