ADHD	attention deficit and hyperactivity disorder
AMICS	Asthma Multicentre Infant Cohort Study
AQG	Air Quality Guide
Al	aluminium
As	arsenic
B(a)P	benzo(a)pyrene
BC	black carbon
BDNF	brain-derived neurotrophic factor
BF	breastfeeding
BILD	Bern–Basel Infant Lung Development
CCHH	China, Children, Homes, and Health study
Cd	cadmium
CD14	cluster of differentiation 14
CO	carbon monoxide
Cu	copper
DHS	Demographic and Health Survey
EBF	exclusive breastfeeding
ET-1	endothelin-1
Fe	iron
FEF50	mid-expiratory flows
FEV1	forced expiratory volume
FLN	fluorene
FVC	forced vital capacity
GDNF	glial cell line-derived neurotrophic factor
GDP	gross domestic product
GPx	glutathione peroxidase
Hg	mercury
IgA, IgM, IgG	immunoglobins A, M, G
IGF-1	insulin-like growth factor 1
INMA	Infancia y Medio Ambiente, the Spanish for Childhood and Environment study
IUGR	intrauterine growth restriction
IQ	intelligence quotient
LC PUFA	long chain polyunsaturated fatty acids
LRI	lower respiratory tract infections
Mn	manganese
NDHS	Nigeria Demographic and Health Survey
Ni	nickel
NMHC	nonmethane hydrocarbon
NOx	nitrogen oxides
O3	ozone
OECD	Organisation for Economic Co-operation and Development
PAF	platelet-activating factor acetylhydrolase
PAHs	polycyclic aromatic hydrocarbons
Pb	lead
PDHS	Pakistan Demographic and Health Survey
PM	particulate matter
PRISMA	Preferred Reporting Items for Systematic Reviews and Meta-Analyses
PROBIT	Promotion of Breastfeeding Intervention Trial
RCT	randomized controlled trial
sCD14	soluble cluster of differentiation 14
SCD	stearoyl-CoA Desaturase
SIDS	sudden infant death syndrome
sIgA	secretory immunoglobin A
SNECCS	Seven Northeastern Cities Chinese Children’s Study
SO2	sulfur dioxide
SOD	superoxide dismutase
TGF-β	transforming growth factor β
TNF-β	tumor necrosis factor β
UFP	ultrafine particles
UVB	ultraviolet B
WHO	World Health Organization
Zn	zinc