Assessing the impact of race, social factors and air pollution on birth outcomes: a population-based study

Table 1 Demographics and clinical metrics of the study population overall and among births with adverse birth outcomes

	All births (n= 457 642)	LBW (n = 30 458)	SGA (n = 42 663)	PTB (n = 40 746)
Mean BWT in g (SD)	3320.8 (573.7)	2003.1 (508.0)	2534.1 (387.2)	2392.6 (717.0)
Gestational age (%)
24-34 weeks	3.3	43.3	4.3	37.2
35-36 weeks	5.6	25.0	7.6	62.8
37-42 weeks	91.1	31.7	88.0	N/A
Infant sex male (%)	51.2	46.9	50.3	53.2
First born (%)	42.7	50.9	52.5	45.7
Trimester prenatal care began (%)
First	84.9	81.0	79.6	83.2
Second	12.6	15.0	16.7	12.4
Third	1.9	1.9	2.6	2.1
None	0.6	2.1	1.1	2.3
Year of birth (%)
2002	19.2	19.1	19.0	19.0
2003	19.3	19.4	19.3	19.5
2004	19.9	19.5	19.2	20.0
2005	20.4	20.5	20.6	20.5
2006	21.1	21.5	22.0	20.9
Race/ethnicity (%)
Non-hispanic white	62.4	39.0	48.2	57.5
Non-hispanic black	22.8	50.2	37.7	31.2
Hispanic	14.8	10.8	14.1	11.3
Maternal education (%)
<9 years	6.2	5.6	6.8	5.3
9-11 years	15.0	21.2	22.5	17.4
12 years	28.4	33.1	33.3	30.7
13-15 years	22.4	21.6	20.0	23.5
>15 years	28.1	18.5	17.4	23.1
Maternal age (%)
15-19 years	11.4	16.4	17.8	13.5
20-24 years	27.2	30.4	33.0	27.6
25-29 years	27.2	23.8	23.7	25.3
30-34 years	22.7	18.3	16.4	21.0
35-39 years	9.9	9.1	7.6	10.5
40-44 years	1.7	2.0	1.6	2.2
Tobacco use (%)	11.7	21.0	22.2	15.5
Married (%)	64.4	49.7	48.1	58.1
Household median income ($)
Mean (SD)	424000 (15490)	39187 (13753)	39284 (14083)	40605 (14403)
Household median income (%)
Low	24.4	30.9	31.2	27.6
Moderate	32.5	34.2	33.9	33.8
High	43.1	34.9	34.9	38.6
PM_2.5 (μg/m³)
Mean (SD)	13.6 (1.7)	13.6 (1.8)	13.7 (1.7)	13.6 (1.8)
Interquartile range	2.0	2.3	2.0	2.3
O₃ in ppb
Mean (SD)	43.2 (4.0)	43.3 (5.0)	43.3 (4.1)	43.2 (5.0)
Interquartile range	5.9	7.4	6.0	7.5

ISSN: 1476-069X