Table 1.

Percentage of Characteristics and Pregnancy Outcomes Within Derivation and Validation Cohorts

	Derivation cohort, % (n=263)	Validation cohort, % (n=146)	Chi-squared p-value
Maternal characteristics
Age<20 years	14.8	14.4	0.39
Unmarried	69.6	68.5	0.82
Unemployed	67.3	66.4	0.86
Primiparous	35.6	28.9	0.16
No high school degree	29.7	32.2	0.59
Maternal race			0.94
Black	59.2	57.0
White	28.5	30.5
Other	12.3	12.5
Tobacco use	19.8	26.0	0.14
Substance abuse within past year	17.5	23.3	0.16
History of childhood rape or abuse	5.7	5.5	0.93
Mental health condition	8.4	6.9	0.58
Homeless	1.9	0.7	0.33
Developmental delay	1.1	0.7	0.65
Hypertensive disorders	1.9	2.0	0.91
Other medical conditions	8.4	8.2	0.96
Body mass index>40	6.9	6.2	0.79
Twin gestation	0.8	2.0	0.25
Short cervix	0.0	0.7	0.18
Prenatal care entry>28 weeks	1.9	2.7	0.58
Interpregnancy interval<18 months	10.3	12.3	0.52
Prior low birth weight infant	4.6	4.8	0.92
Prior preterm birth	10.3	8.2	0.50
Prior intrauterine fetal demise/ neonatal death	4.6	6.9	0.33
Outcomes
Preterm birth	8.4	8.9	0.85
Birth weight<2500 grams	11.4	13.0	0.63
Intrauterine fetal demise/ neonatal death	0.4	0.7	0.67
Composite adverse outcome	15.2	15.8	0.88