Table 1.

Case-control analyses in the overall sample (all ages, all indications).

Characteristica	Bilateral Oophorectomy (n=1,653)			Control Women (n=1,653)		Adjusted Odds Ratio (95% Cl)b	p Value
	N	%		N	%
Age at menarchec
<12	147	9.8		135	10.0	1.00 (reference)	--
12	548	36.7		458	34.0	1.17(0.87, 1.58)	0.30
13	572	38.3		488	36.3	1.06(0.79, 1.42)	0.70
>13	226	15.1		265	19.7	0.79(0.57, 1.10)	0.16
Oral contraceptive use (ever vs. never)d	841	50.9		1,000	60.5	0.65 (0.57, 0.75)	<0.001
Years of oral contraceptive usec,e
0 or <0.5	812	51.3		653	42.1	1.00 (reference)	--
0.5–4.9	402	25.4		349	22.5	0.90(0.75, 1.08)	0.26
≥5.0	369	23.3		550	35.4	0.51 (0.43, 0.61)	<0.001
Gravidityc
0d	253	15.3		227	13.7	1.00 (reference)	--
1	164	9.9		179	10.8	0.82(0.62, 1.09)	0.17
2	496	30.0		481	29.1	0.91 (0.73, 1.14)	0.40
≥3	740	44.8		766	46.3	0.86(0.70, 1.07)	0.17
Twin or multiple gestationd	42	2.5		33	2.0	1.25(0.79, 1.98)	0.34
Pregnancy lossd	550	33.3		531	32.1	1.07(0.92, 1.25)	0.36
Induced abortiond,f	92	5.6		118	7.1	0.77(0.58, 1.02)	0.07
Spontaneous abortion or still birthd	488	29.5		454	27.5	1.13(0.96, 1.32)	0.13
Parityc
0d	313	18.9		279	16.9	1.00 (reference)	--
1	194	11.7		216	13.1	0.80(0.62, 1.04)	0.09
2	619	37.4		595	36.0	0.91 (0.74, 1.11)	0.35
≥3	527	31.9		563	34.1	0.83(0.67, 1.02)	0.08
Breast feeding	493	40.8		655	51.2	0.68(0.56, 0.81)	<0.001
lnfertilityd	292	17.7		164	9.9	1.95(1.59, 2.40)	<0.001
Fibrocystic breast diseased	1,083	65.5		1,128	68.2	0.85(0.72, 1.00)	0.047
Smoking statusc
Neverd	897	54.3		957	57.9	1.00 (reference)	--
Former	393	23.8		377	22.8	1.06(0.90, 1.26)	0.49
Current	363	22.0		319	19.3	1.15(0.96, 1.39)	0.13
Pack-yearsc,e
0	897	54.6		957	59.1	1.00 (reference)	--
0.1–5.9	180	10.9		167	10.3	1.11 (0.88, 1.40)	0.39
≥6.0	567	34.5		495	30.6	1.16(0.99, 1.36)	0.06
Height (cm)c,e
<161.0	509	30.8		529	32.1	1.00 (reference)	--
161.0–166.9	602	36.4		579	35.2	1.04(0.87, 1.23)	0.67
≥167.0	542	32.8		538	32.7	1.01 (0.85, 1.21)	0.92
Weight (kg)c,e
<64.0	455	27.5		573	35.0	1.00 (reference)	--
64.0–78.9	556	33.6		564	34.5	1.23(1.03, 1.46)	0.02
≥79.0	642	38.8		499	30.5	1.58(1.32, 1.89)	<0.001
Body mass index (kg/m2)c
<25.0	596	36.1		700	42.9	1.00 (reference)	--
25.0–29.9	481	29.1		488	29.9	1.17(0.99, 1.39)	0.07
≥30.0	576	34.8		442	27.1	1.51 (1.27, 1.79)	<0.001

^aWomen with missing or unknown data were not included in the respective analysis for the following characteristics: 467 for age at menarche (160 cases and 307 controls), 171 for years of birth control use (70 cases and 101 controls), 817 for breast feeding status (444 cases and 373 controls), 43 for smoking pack-years (9 cases and 34 controls), and 23 women for height, weight, and/or body mass index (0 cases and 23 controls).

^bThe odds ratios and confidence intervals for each characteristic were calculated using conditional logistic regression models (matched pairs) adjusted for years of education (≤12; 13–16; >16), race (white; non-white) and quartiles of household income (<$42,000; $42,000–56,999; $57,000–71,999; ≥$72,000). Women with unknown education (3 cases and 35 controls) were assigned to the ≤12 years group, and women with unknown income (6 cases and 2 controls) were assigned to the $42,000–56,999 group (second quartile).

^cOrdinal characteristics were also tested for dose-effect (i.e., linear) trends adjusted for years of education, race, and household income: age at menarche (p=0.02), years of oral contraceptive use (p<0.001), gravidity (p=0.31), parity (p=0.18), smoking status (p=0.13), pack-years (p=0.06), height (p=0.93), weight (p<0.001), and body mass index (p<0.001).

^dFor these characteristics, women with missing or unknown data were included in the no exposure category.

^eYears of oral contraceptive use, smoking pack-years, height, and weight were stratified using tertiles calculated from the overall sample (case-control groups pooled).

^fWe may have underestimated induced abortions performed outside of the medical care facilities included in the REP.