Table 4.

Independent effects of traffic and land use (not including SEM variables: education, race, APNCU, and median household income) in a study of singleton births in Eastern Massachusetts between 1996 and 2002.

	Birth weight		Small for gestational age		Preterm birth
Model covariates*	Change (in grams)	95% CI	OR	95% CI	OR	95% CI
Cumulative traffic density	-2.0	-3.7, -0.3	1.02	1.01, 1.04	1.00	0.98, 1.01
Distance to major highways	5.7	3.4, 7.9	0.98	0.97, 0.99	1.00	0.99, 1.02
% land use for recreation and conservation (open space)	13.4	10.4, 16.5	0.96	0.95, 0.97	1.01	1.00, 1.03

APNCU – adequacy of prenatal care utilization; CI – confidence interval; OR – odds ratio; SD – standard deviation; SEM – socioeconomic measures

Model controlled additionally for race (where appropriate) mother age, gestational age (for models with birth weight as the outcome), cigarette smoking during pregnancy, previous infant greater than 4000 grams, previous preterm birth, chronic or gestational conditions of mother, and year of birth.

*The effect is for 1 SD change in distribution of log-transformed traffic exposures and 1 SD change in distribution of % open space by census tract.