Table 1.

Demographic and selected ovarian cancer risk factors among participants; the Shanghai Women’s Health Study

Characteristics	Cases*	Non-Cases*	P**
Participants (N)	174	70085	–
Total person-years	1132.4	887126.0	–
Age at recruitment	52.6±8.7	52.5±9.1	0.90
Education			0.83
Elementary School or below	40 (23.0%)	15074 (21.5%)
Junior high shool	59 (33.9%)	26179 (37.4%)
High School	51 (29.3%)	19504 (27.8%)
College or above	24 (13.8%)	9315 (13.3%)
Ever married	173 (99.43%)	69480 (99.12%)	1.00
Age at menarche	14.9±1.7	14.9±1.7	0.63
Ever had irregular ovulatory cycles	5 (2.9%)	4688 (6.7%)	0.04
History of infertility	3 (1.7%)	362 (0.5%)	0.06
Ever pregnant	167 (96.0%)	68297 (97.5%)	0.22
Ever had a live birth	167 (96.0%)	67873 (96.8%)	0.51
Ever had an abortion	89 (51.2%)	40973 (58.5%)	0.05
Ever had a miscarriage	27 (15.5%)	8347 (11.9%)	0.14
Ever had salpingocyesis or ectopic pregnancies	3 (1.7%)	702 (1.0%)	0.25
Number of pregnancies	2.8±1.5	2.8±1.5	0.89
Number of live births	1.8±1.3	1.8±1.2	0.97
Premenopausal	87 (50.0%)	36653 (52.3%)	0.54
Age at menopause1	50.1±3.4	49.2±3.7	0.03
Total weeks of pregnancies	77.7±50.4	78.2±49.8	0.88
Total months of breastfeeding	16.0±20.0	15.6±18.4	0.78
Total years of ovulation	29.5±4.8	28.7±5.0	0.03
Ever used hormone replacement therapy (HRT)	3 (1.7%)	1154 (1.7%)	0.77
First-degree family history of cancer	50 (28.7%)	18443 (26.3%)	0.47
Family history of breast cancer or ovarian cancer	4 (2.3%)	1473 (2.1%)	0.79
Exercised regularly in past 5 years	60 (34.5%)	24372 (34.8%)	0.94
Ever smoked regularly	8 (4.6%)	1951 (2.8%)	0.16
Ever drank regularly	5 (2.9%)	1585 (2.3%)	0.60
Ever drank tea regularly	53 (30.5%)	20946 (29.9%)	0.87
BMI	24.4±3.8	24.0±3.4	0.15

¹Among women with natural menopause

^*n (%) for categorical variables or mean ± sd for continuous variables

^**P-values derived from χ² or exact tests for categorical variables or t-tests for continuous variables