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Table 1 Socio-demographic characteristics of all enrolled participants

From: Risk factors for ectopic pregnancy: a multi-center case-control study

 

EP

IUP

OR [95 % CI]

p value

n a

(%)

n a

(%)

Age (year)

 ≤20

24

(1.00)

32

(1.33)

Reference

0.16

 20–24

363

(15.06)

398

(16.47)

1.22 [0.70, 2.10]

 25–29

753

(31.23)

772

(31.95)

1.30 [0.76, 2.23]

 30–34

793

(32.89)

755

(31.25)

1.40 [0.82, 2.40]

 35–39

332

(13.77)

322

(13.33)

1.38 [0.79, 2.39]

 ≥40

146

(6.06)

137

(5.67)

1.42 [0.80, 2.53]

Marital status

 Married

2067

(85.80)

2088

(86.42)

Reference

0.56

 Unmarried

342

(14.20)

328

(13.58)

0.92 [0.78, 1.08]

Birth place

      

 Shanghai

698

(28.95)

775

(32.08)

Reference

<10−3

 Outside of Shanghai

1713

(71.05)

1641

(67.92)

1.16 [1.03, 1.31]

Education attainment

 Collage or above

1061

(44.01)

1378

(57.04)

Reference

<10−3

 High school

314

(13.02)

280

(11.59)

1.46 [1.22, 1.74]

 Middle school

178

(7.38)

195

(8.07)

1.19 [0.95, 1.48]

 Primary school or lower

858

(35.59)

563

(23.30)

1.98 [1.73, 2.26]

Occupation

 Employed

1682

(69.88)

1897

(78.58)

Reference

<10−3

 Self-employed

262

(10.89)

184

(7.62)

1.61 [1.32, 1.96]

 Unemployed

463

(19.24)

333

(13.80)

1.57 [1.34, 1.83]

Personal annual income (RMB)

 <50,000

1165

(48.32)

1093

(45.24)

Reference

0.13

 50,000-100,000

777

(32.23)

841

(34.81)

0.87 [0.76, 0.99]

 > 100,000

469

(19.45)

482

(19.95)

0.91 [0.79, 1.06]

Smokingb

 None smoker

2298

(95.31)

2294

(96.18)

Reference

0.41

 Occasional smoker

63

(2.61)

57

(2.39)

1.10 [0.77, 1.59]

 Regular smoker

50

(2.07)

34

(1.43)

1.47 [0.95, 2.28]

Institutionsc

 1

1404

(58.23)

1409

(58.32)

Reference

1.00

 2

276

(11.45)

274

(11.34)

1.01 [0.84, 1.21]

 3

291

(12.07)

293

(12.13)

1.00 [0.83, 1.19]

 4

272

(11.28)

272

(11.26)

1.00 [0.84, 1.21]

 5

168

(6.97)

168

(6.95)

1.00 [0.80, 1.26]

  1. EP ectopic pregnancy, IUP intrauterine pregnancy, OR odds ratio, CI confidence interval
  2. aThe sum does not necessarily equal the sample size for all variables because of missing data
  3. 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
  4. cCenter 1 = International Peace Maternity and Child Health Hospital; Center 2 = Shanghai First People's Hospital; Center 3 = Songjiang Central Hospital; Center 4 = Songjiang Maternity and Child Health Hospital; Center 5 = Minhang Central Hospital