Table 1.

Participants’ characteristics by history of infertility for the index pregnancy (n = 2201)^a

	History of infertility
	Yes n = 414 (18.8%)b		No n = 1787 (81.2%)
Maternal characteristics at enrollment
	Mean	SD	Mean	SD
Pre-pregnancy BMI, kg/m2	25.1	5.6	24.8	5.6
	N	%	N	%
Age
18–29 years	63	15.2	602	33.7
30–34 years	151	36.5	764	42.8
≥ 35 years	200	48.3	421	23.6
Race/ethnicity
White	304	74.3	1149	65.3
Asian	19	4.6	104	5.9
Black	52	12.7	306	17.4
Hispanic	19	4.6	135	7.7
Other	15	3.7	66	3.8
College graduate
No	110	26.9	661	37.6
Yes	299	73.1	1099	62.4
Married/cohabiting
No	12	2.9	165	9.4
Yes	397	97.1	1594	90.6
Household income > $70,000/year
No	123	33.2	617	40.4
Yes	248	66.8	909	59.6
Pregnancy smoking status
Former smoker	84	20.9	312	18.3
Smoked during pregnancy	32	8.0	233	13.6
Never smoker	286	71.1	1162	68.1
Nulliparous
No	184	44.4	969	54.2
Yes	230	55.6	818	45.8
Age at first period
< 12 years	37	17.7	144	16.8
12 to 14 years	153	73.2	615	71.8
≥ 15 years	19	9.1	97	11.3

BMI body mass index

^aThe sample includes 2201 women with data on the exposure and ≥ 1 pregnancy outcome. The description was conducted using non-imputed data. The sample may not add to 2201 due to missing covariate values

^bAmong women with infertility for the index pregnancy, 135 (32.6%) used medically assisted reproduction: 46 (34.1%) used clomiphene citrate alone, or with gonadotropins or gonadotropin-releasing hormone agonists, 79 (58.5%) reported gonadotropins or gonadotropin-releasing hormone agonists, and 10 (7.4%) used other treatments