Air pollution exposure during pregnancy and reduced birth size: a prospective birth cohort study in Valencia, Spain

Table 3 Association between individual exposure to ambient NO₂ >40 μg/m³ in different time periods during pregnancy and anthropometric measures at birth.*

	Birth weight (in g)^a (n:785)		Birth length (in cm)^a (n:784)		Birth head circumference (in cm)^a (n:782)
NO₂ exposure period	β	(95% CI)	β	(95% CI)	β	(95% CI)
Unadjusted
First trimester	-24.309	(-78.256; 29.638)	-0.300	(-0.526; -0.075)	-0.104	(-0.276; 0.069)
Second trimester	-9.648	(-65.156; 45.860)	-0.100	(-0.333; 0.133)	-0.173	(-0.352; 0.005)
Third trimester	28.325	(-26.475; 83.126)	0.150	(-0.079; 0.379)	0.051	(-0.123; 0.226)
Whole pregnancy	-16.912	(-71.233; 37.410)	-0.170	(-0.398; 0.058)	-0.152	(-0.326; 0.022)
Adjusted ^b
First trimester	-40.349	(-96.267; 15.568)	-0.271	(-0.514; -0.028)	-0.074	(-0.257; 0.108)
Second trimester	-37.546	(-96.231; 21.140)	-0.190	(-0.447; 0.066)	-0.177	(-0.368; 0.014)
Third trimester	26.656	(-28.239; 81.551)	0.077	(-0.161; 0.315)	0.011	(-0.167; 0.190)
Whole pregnancy	-33.292	(-84.874; 18.290)	-0.199	(-0.424; 0.027)	-0.171	(-0.339; -0.003)

*Estimates are expressed as the change in birth anthropometric measures comparing NO₂ exposure levels >40 μg/m³ vs. exposure levels ≤40 μg/m³ at each woman residence during the corresponding period. Unadjusted and adjusted models.
^a Standardized for gestational age.
^b Adjusted for:
-Birth weight: maternal age, maternal pre-pregnancy weight, maternal height, paternal height, gestational weight gain, parity, maternal education, smoking during pregnancy, country of origin, sex of the infant, and season of last menstrual period.
-Birth length: maternal age, maternal height, gestational weight gain, parity, maternal working status in the first trimester, smoking during pregnancy, country of origin, sex of the infant, and season of last menstrual period.
-Birth head circumference: maternal age, maternal pre-pregnancy weight, maternal height, gestational weight gain, parity, maternal education, smoking during pregnancy, working status in the third trimester, sex of the infant, and season of last menstrual period.

ISSN: 1476-069X