Table 1.

Population characteristics (N=476).

		N	Weighted %
Age	<25 years	52	12%
	25–30 years	95	20%
	30–35 years	187	39%
	>35 years	142	29%
Race/ethnicity	White	279	59%
	African American	77	16%
	Other	120	25%
Pre-pregnancy BMI (missing=11)	< 25 kg/m2	257	56%
	25–30 kg/m2	119	26%
	>30 kg/m2	89	18%
Health insurance (missing=12)	Private	375	80%
	Public	89	20%
Education (missing=11)	High school	67	14%
	Technical school	77	16%
	Junior/some college	136	29%
	College graduate	185	41%
Fetal sex	Male	210	44%
	Female	266	56%
Assisted reproductive technology	No	426	89%
	Yes	50	11%
In vitro fertilization	No	446	94%
	Yes	30	6%
Nulliparous	No	266	55%
	Yes	210	45%
Gravid	No	140	30%
	Yes	336	70%
Tobacco use in pregnancy	No	448	95%
	Yes	28	5%
Alcohol use in pregnancy (missing=10)	No	447	95%
	Yes	19	5%
Preterm	No	347	88%
	Yes	129	12%