Prenatal air pollution exposure and growth and cardio-metabolic risk in preschoolers

Objectives: We investigated the association between outdoor air pollutants exposure in the first trimester of pregnancy, and growth and cardio-metabolic risk at four years of age, and evaluated the mediating role of birth weight. Methods: We included mother-child pairs (N = 1,724) from the Spanish INMA birth cohort established in 2003-2008. First trimester of pregnancy nitrogen dioxide (NO2) and fine particles (PM2.5) exposure levels were estimated. Height, weight, waist circumference, blood pressure, and lipids were measured at four years of age. Body mass index (BMI) trajectories from birth to four years were identified. Results: Increased PM2.5 exposure in the first trimester of pregnancy was associated with decreased z-scores of weight (zWeight) and BMI (zBMI) (zWeight change per interquartile range increase in PM2.5 exposure = -0.12; 95% CI: -0.23, -0.01; zBMI change = -0.12; 95% CI: -0.23, -0.01). Higher NO2 and PM2.5 exposure was associated to a reduced risk of being in a trajectory with accelerated BMI gain, compared to children with the average trajectory. Birth weight partially mediated the association between PM2.5 and zWeight and zBMI. PM2.5 and NO2 were not associated with the other cardio-metabolic risk factors. Conclusions: This comprehensive study of many growth and cardio-metabolic risk related outcomes suggests that air pollution exposure during pregnancy may be associated with delays in physical growth in the early years after birth. These findings imply that pregnancy exposure to air pollutants has a lasting effect on growth after birth and require follow-up at later child ages. This study was funded by grants from the Eulji University (grant numbers ESCAPE project FP7-ENV-2007-1-211250, DENAMIC project FP7-ENV-2011-282957, HELIX project FP7-ENV-2012-308333, and MEDALL project HEALTH.2010.2.4.5-1), from the Spanish Instituto de Salud Carlos III (grant numbers Red INMA G03/176; CB06/02/0041; PI03/1615 incl. FEDER funds, PI04/1112 incl. FEDER funds, PI041436, PI04/1509 incl. FEDER funds, PI04/1931 incl. FEDER funds, PI042018 incl. FEDER funds, PI05/1079 incl. FEDER funds, PI05/1052 incl. FEDER funds, FIS-PI06/0867, PI06/1213 incl. FEDER funds, PI07/0314 incl. FEDER funds, PI081151 incl. FEDER funds, FIS-PI09/00090, PI09/02311 incl. FEDER funds, PI09/02647 incl. FEDER funds, PI11/01007 incl. FEDER funds, PI11/02591 incl. FEDER funds, PI11/02038 incl. FEDER funds, PI13/1944 incl. FEDER funds, PI13/2032 incl. FEDER funds, PI13/02429 incl. FEDER funds, PI14/00891 incl. FEDER funds, PI14/01687 incl. FEDER funds, PI15/00118 incl. FEDER funds, PI16/1288 incl. FEDER funds, and PI17/00663 incl. FEDER funds, PI18/00547 incl. FEDER funds, PI18/00909 incl. FEDER funds; CP11/00178, CP15/00025, and CPII16/00051; MS13/00054 incl. FEDER funds), CIBERESP, Department of Health of the Basque Government (grant numbers 2005111093, 2013111089), Generalitat de Catalunya-CIRIT (grant numbers 1999SGR 00241), Generalitat Valenciana: FISABIO (grant numbers UGP 15-230, UGP-15-244, and UGP-15-249), Provincial Government of Gipuzkoa (grant number DFG06/002), Alicia Koplowitz Foundation 2017, Fundacio La marato de TV3 (grant number 090430), Obra Social Cajastur/Fundacion Liberbank, Universidad de Oviedo, and annual agreements with the municipalities of the study area of the Gipuzkoa sub-cohort (Zumarraga, Urretxu, Legazpi, Azkoitia, Azpeitia and Beasain). ISGlobal is a member of the Agency for the Research Centres of Catalonia (CERCA) Programme, Generalitat de Catalunya.