Table 1.

Baseline clinical characteristics of tubal EM and Non tubal EM.

Variables	Non Tubal EM (n=951)		Tubal EM (n=161)		P value
	n a	%	n a	%
Socio-demographic characteristics
Age (years) (mean±SD)	45.90 ± 5.97		44.89 ± 6.00		0.02
BMI (kg/m2) (mean±SD)	23.01 ± 3.17		22.61 ± 2.99		0.09
Marital status
Married	885	93.05	145	90.06	0.18
Unmarried	66	6.95	16	9.94
Birth place
Shanghai	625	65.72	111	68.94	0.42
Out of Shanghai	326	34.28	50	31.06
Educational attainment
Primary school or lower	223	23.45	37	22.98	0.99
Middle school	104	10.94	17	10.56
High school	142	14.93	23	14.29
University or above	482	50.68	84	52.17
Individual annual income (¥)
<50,000	257	27.02	46	28.57	0.89
50,000-100,000	456	47.95	77	47.83
>100,000	238	25.03	38	23.60
Smoking status b
Non-smoker	890	93.58	151	93.79	0.99
Occasional smoker	48	5.05	8	4.97
Regular smoker	13	1.37	2	1.24
Reproductive history
Previous abortions (mean ± SD)	1.05 ± 1.01		0.98 ± 0.81		0.38
Parity (mean ± SD)	1.13 ± 0.73		1.24 ± 0.78		0.28
Cesarean section	214	22.50	44	27.33	0.18
Gynecologic history
Abnormal uterine bleeding c	476	50.05	126	78.26	<10-3
Previous confirmed endometriosis d	38	2.52	31	14.29	<10-3
Pelvic inflammatory disease	76	7.99	14	8.70	0.76
Previous tubal ligation	60	6.31	18	11.18	0.02
Previous IUD use	80	8.41	10	6.21	0.34

EM:endometriosis; SD:standard deviation; BMI:Body Mass Index.

^aThe sum does not necessarily equal the sample size for all variables because of missing data.

^bOccasional smoker:cigarette smoking more than 4 times a week, but a day on average less than 1 cigarette. Regular smoker:cigarette smoking more than 1 cigarettes per day, continuous or accumulated 6 months.

^cAbnormal uterine bleeding was diagnosed using the FIGO classification system [9].

^dIt was confirmed by previous operation pathology.