. 2012 Sep 11;176(7):635–641. doi: 10.1093/aje/kws145

Table 2.

Relation of Pregnancy-Related Factors to Sarcoidosis Incidence in the Black Women's Health Study, United States, 1995–2009

	No. of Cases	No. of Person-Years	IRR^a	95% CI	IRR^b	95% CI
Parity
Nulliparous women	124	212,222	1.00	Reference	1.00	Reference
Parous women	327	481,270	1.05	0.85, 1.30	1.00	0.80, 1.24
1	104	163,578	1.00	0.77, 1.30	0.97	0.74, 1.26
2	120	172,397	1.05	0.81, 1.36	1.00	0.77, 1.30
≥3	103	145,295	1.13	0.86, 1.49	1.03	0.78, 1.37
P-trend						0.77
Age at first birth, years^c
<20	119	150,219	1.00	Reference	1.00	Reference
20–24	117	161,506	0.95	0.73, 1.22	0.96	0.74, 1.25
25–29	61	100,439	0.78	0.57, 1.06	0.80	0.58, 1.11
≥30	26	65,347	0.51	0.33, 0.78	0.52	0.34, 0.82
P-trend					0.02
Years since last birth^c
<5	32	64,280	0.55	0.34, 0.88	0.56	0.35, 0.91
5–9	41	65,009	0.64	0.43, 0.96	0.66	0.44, 0.99
10–14	55	65,102	0.85	0.60, 1.19	0.85	0.61, 1.20
≥15	190	277,410	1.00	Reference	1.00	Reference
P-trend						0.01
Lactation^c
Never lactating	200	271,837	1.00	Reference	1.00	Reference
Ever lactating, months	123	204,566	0.83	0.66, 1.03	0.87	0.69, 1.09
<6	74	112,568	0.91	0.69, 1.19	0.95	0.72, 1.24
6–11	19	41,747	0.66	0.41, 1.05	0.69	0.43, 1.12
≥12	30	50,250	0.78	0.53, 1.15	0.82	0.56, 1.21
P-trend						0.25

Abbreviations: CI, confidence interval; IRR, incidence rate ratio.

^a Adjusted for age.

^b Adjusted for age, education, geographic region, smoking, and body mass index.

^c Restricted to parous women.