Prenatal Ambient Particulate Matter Exposure and Longitudinal Weight Growth Trajectories in Early Childhood

Abstract

Air pollution exposure during pregnancy has been associated with impaired fetal growth and postnatal weight gain, but few studies have examined the effect on weight growth trajectories. We examine the association between validated 1 km2 resolution particulate matter (PM2.5) concentrations, averaged over pregnancy, and sex-specific growth trajectories from birth to age six of participants in the Boston-based Children’s HealthWatch cohort (4797 participants, 84,283 measures). We compared weight trajectories, predicted using polynomial splines in mixed models, between prenatal PM2.5 above or below the median (9.5 µg/m3), and examined birth weight as an effect modifier. Females exposed to average prenatal PM2.5 ≥ 9.5 µg/m3 had higher weights compared to females exposed to < 9.5 µg/m3 throughout the study period (0.16 kg at 24 months, 0.61 kg at 60 months). In males, higher prenatal PM2.5 exposure was associated with significantly lower weights after 24 months of age, with differences increasing with time (−0.17 at 24 months, −0.72 kg at 60 months). Associations were more pronounced among low birth weight (<2500 g) females, but did not differ by birth weight status in males. Our findings demonstrate the complex association between air pollution exposures and childhood weight trajectories and emphasize the importance of sex-stratified analyses.

Prenatal exposure to ambient air pollutants and early infant growth and adiposity in the Southern California Mother’s Milk Study

“…Upon examination of non-linearity, positive associations of particulate matter with infant body composition appeared to plateau beyond the first tertile of exposure. Consistent with previous studies [ 11 , 22 ], we observed sex-specific findings. O x wt was associated with change in umbilical circumference and a modestly larger increase in CTSF, with these associations observed only among females and males, respectively, following stratification by sex.…”

“…These covariates were chosen based on known associations with infant growth parameters and/or AAP exposure levels [ 34 ]. Based upon previous literature [ 11 ], infant sex was also examined as a potential effect modifier of the relationship between ambient air pollution and early infant growth. Sensitivity analyses were also performed, which additionally adjusted for birth weight and the baseline variable of each change outcome.…”

“…Recent work supports the hypothesis that developmental programming during the pre-, peri-, and early postnatal periods is sensitive to certain exposures (e.g., maternal nutrition/obesity) that appear to play a critical role in future obesity risk [ 6 ]. Exposure to air pollutants during these periods is also suggested as a risk factor for low birth weight, accelerated growth in early life, and/or childhood obesity [ 7 – 11 ]. This may partially explain the aforementioned disparities in childhood obesity, as Hispanics are exposed to higher levels of ambient (AAP) and traffic-related air pollutants [ 12 , 13 ].…”

“…Another important consideration with respect to in utero exposures and both fetal and infant growth patterns is the existence of sex-specific effects [ 19 – 21 ]. For instance, greater prenatal PM 2.5 (particulate matter < 2.5 microns in aerodynamic diameter) exposure has been linked to lower weight at 2 years of age and beyond in males and an increased weight trajectory in females across the first 6 years of life [ 11 ] and greater waist-to-hip ratio among girls and increased fat mass and BMI z-score among boys at 4 years [ 22 ]. Two studies examining 1 st trimester PM 2.5 exposure found decreased adiposity among 5-month-old girls [ 17 ] and attenuated weight z-scores among pre-school males [ 23 ], respectively.…”

Particulate Matter, an Intrauterine Toxin Affecting Foetal Development and Beyond

“…However, the situation seems more complex in humans, whose mothers are normally exposed to PM during both pre-conceptional and gestational periods. In humans, only girls show this predicted trend, whereas boys with intrauterine exposure to a higher level of PM remain underweight in childhood [ 60 ]. This may suggest that there is an additive effect between pre-conceptional and gestational exposures or even postnatal exposure, as babies normally live in the same environment as mothers.…”