Table 1.

Characteristics of Participants (n = 283) in the Study for Future Families, a US Multicenter Pregnancy Cohort Study, 2000–2004

Characteristic	Overall		Study Center
			California		Iowa		Minnesota		Missouri
	No. or Mean	%	No. or Mean	%	No. or Mean	%	No. or Mean	%	No. or Mean	%
No. of subjects	283	100	48	17	80	28	87	31	68	24
Time between urine collection and delivery, weeksa
Mean	12 (8)b		14 (8)		11 (8)		12 (8)		12 (6)
First trimester	5	2	1	2	0	0	4	5	0	0
Second trimester	119	42	24	51	34	43	34	39	27	40
Third trimester	157	56	22	47	45	57	49	56	41	60
Sex of baby
Male	143	51	24	50	38	47	45	52	36	53
Female	140	49	24	50	42	53	42	48	32	47
Parity (no. of prior livebirths)***
0	145	51	30	63	32	40	52	60	31	46
1	87	31	11	23	25	31	27	31	24	35
≥2	51	18	7	15	23	29	8	9	13	19
Racec,***
White	238	84	22	46	72	91	84	97	60	88
Hispanic	26	9	20	42	2	3	0	0	4	6
Other	18	6	6	13	5	6	3	3	4	6
Education*
High school or less	25	9	9	19	6	8	3	3	7	10
Some college	63	22	19	40	14	18	20	23	10	15
College graduation	106	38	10	21	34	43	33	38	29	43
Graduate school	89	31	10	21	26	33	31	36	22	32
History of miscarriage (yes/no)	60	21	9	19	20	25	14	16	17	25
Employed during pregnancy (yes/no)	231	82	33	69	63	79	79	91	56	82
Job-related stress
No work-related stress	52	18	15	31	17	21	8	9	12	18
Not at all stressful	17	6	2	4	4	5	6	7	5	7
Not too stressful	80	28	14	29	21	26	29	33	16	24
Somewhat stressful	105	37	12	25	32	40	35	40	26	38
Very stressful	29	10	5	10	6	8	9	10	9	13
Maternal health
Diabetes	14	5	4	8	6	8	1	1	3	4
Thyroid disorders	17	6	5	10	5	6	2	2	5	7
Fibroids*	16	6	1	2	8	10	2	2	5	7
High blood pressure	19	7	4	8	5	6	5	6	5	7
Respiratory conditions	26	9	4	8	10	13	5	6	7	10
Mean creatinine level, mg/dL	92 (61)		99 (63)		93 (64)		82 (51)		97 (66)
Mean maternal age, years*	30.2 (6.0)		28.3 (6.0)		30.6 (4.6)		30.8 (5.3)		30.3 (4.6)
Gestational age at delivery (clinical estimate), weeksd
Mean**	39.2 (1.5)		38.9 (1.3)		38.9 (1.3)		39.7 (1.3)		39.1 (1.8)
<37	14	5	3	6	4	5	2	2	5	7
37–41	262	93	45	94	76	95	81	93	60	88
>41	7	2	0	0	0	0	4	5	3	4

* P < 0.05; **P < 0.01; ***P < 0.001 (P for difference between at least 2 of the 4 study centers).

^aInformation on timing of urine sample collection was missing for 2 participants.

^bNumbers in parentheses, standard deviation.

^cInformation on race was missing for 1 participant.

^dClinical estimate of gestational age abstracted from the birth medical record; values were reported rounded to the next-highest week. Information was missing for 1 participant.