Table 3.

Associations between average 8-hour daily maximum O₃ at the residential address during pregnancy and infant weight and adiposity outcomes.

	Birth weight (n=1,125)^a			Adiposity at birth (n=951)^b			Adiposity at 5-month follow-up (n=574)^c

Time interval of O₃ average	Difference (g) per IQR^dand 95% CI		p-value for sex interaction	Difference (%) per IQR^d and 95% CI		p-value for sex interaction	Difference (%) per IQR^dand 95% CI		p-value for sex interaction
Both sexes
Trimester 1	24.5	(−100.7, 149.8)	0.61	1.05	(−0.36, 2.46)	0.61	−0.69	(−3.11, 1.74)	0.97
Trimester 2	−18.3	(−140.5, 103.9)	0.38	0.24	(−1.11, 1.59)	0.69	0.10	(−2.33, 2.54)	0.38
Trimester 3	20.3	(−88.0, 128.7)	0.31	0.40	(−0.80, 1.60)	0.96	2.16	(0.07, 4.26)	0.53
Full pregnancy	−1.0	(−63.0, 61.0)	0.81	0.58	(−0.11, 1.26)	0.75	0.31	(−0.86, 1.47)	0.73

Abbreviations: CI, confidence interval; IQR, interquartile range; O₃, ozone; PM_2.5, particulate matter with diameter ≤ 2.5 micrometers.

Model 1: Adjusted for maternal age, pre-pregnancy BMI, gestational weight gain, education, race/ethnicity, smoking during pregnancy, gravidity, infant sex, gestational age at birth, year of birth, season of birth, average temperature and average daily PM_2.5 concentration during the specified pregnancy period, and percentage of persons below the poverty level in the Census tract of residence.

Model 2: Adjusted for Model 1 variables and infant age in days at neonatal body composition measurement.

Model 3: Adjusted for Model 1 variables except gestational age at birth, and additionally adjusted for infant age in days at follow-up and exclusive breastfeeding.

IQRs for O₃: Trimester 1, 19.6 ppb; Trimester 2, 18.6 ppb; Trimester 3, 18.4 ppb; Full pregnancy, 5.9 ppb.