A population-based study of race-specific risk for placental abruption

Table 1 Baseline characteristics by race for individual births (n = 664,303)

Characteristics	Black	White
	n (%)	n (%)	P*
Total births	108,806 (16.4)	555,497 (83.6)	< 0.001
Mean gestational age at delivery	38.4 ± 3.1	39.1 ± 2.2	< 0.001
Maternal age (years)	23.9 ± 5.9	26.6 ± 5.7	< 0.001
Maternal age categories			< 0.001
Age < 20 years	28,727 (26.4)	65,785 (11.8)
Age ≥ 20 and < 35 years	73,736 (67.8)	437,468 (78.8)
Age ≥ 35 years	6,326 (5.8)	52,218 (9.4)
Maternal education < 12 years	35,192 (33.0)	94,925 (17.2)	< 0.001
Indicators of low socioeconomic status†	86,303 (79.8)	207,159 (37.4)	< 0.001
Unmarried	84,362 (77.6)	120,187 (21.7)	< 0.001
Primigravida	40,163 (37.0)	231,226 (41.7)	< 0.001
No prenatal care	5,094 (4.9)	3,966 (0.7)	< 0.001
Body mass index categories			< 0.001
Body mass index < 20	17,814 (17.1)	116,300 (21.5)
Body mass index ≥ 20 and ≤ 30	67,678 (65.0)	355,828 (65.8)
Body mass index > 30	18,661 (17.9)	68,875 (12.7)
Type I or II Diabetes	2,480 (2.3)	13,400 (2.4)	0.120
Chronic hypertension	1,408 (1.3)	3,932 (0.7)	< 0.001
Gestational hypertension	5,570 (5.1)	21,515 (3.9)	< 0.001
Renal disease	326 (0.3)	1,258 (0.2)	< 0.001
Alcohol use	3,644 (3.4)	11,311 (2.0)	< 0.001
Cigarette use	19,340 (17.9)	126,897 (22.9)	0.002

* The p value for a chi-square test, adjusted for clustering for more than one birth to one mother.
† The composite indicator of low socioeconomic status, which includes Medicaid, WIC or food stamps.
Some percentages do not add up due to missing values (less than 5% for any given variable).

ISSN: 1471-2393