Table 3 The odds ratio of infertility by demographic characteristics and fertility experiences

Age(years)

16–29

–

–

–

–

–

30–34

0.960–1.555

0.104

1.094

0.817–1.466

0.547

35–39

1.773–3.172

0.000

1.885

1.307–2.719

0.001

40–44

2.199–5.134

0.000

2.554

1.490–4.375

0.001

45–50

1.647–9.448

0.002

2.897

1.068–7.859

0.037

Body mass index (kg/m²)

 < 18.5

–

–

–

–

–

18.5–24.9

0.792–1.410

0.708

0.895

0.650–1.233

0.498

25–29.9

0.842–1.812

0.279

0.815

0.527–1.260

0.357

 ≥ 30

1.193–3.550

0.009

1.364

0.738–2.519

0.322

Smoking

Never or former smoker

–

–

–

–

–

Current smoker

1.102–1.943

0.008

1.156

0.832–1.607

0.387

Delivery status

Nullipara

–

–

–

–

–

Have children

1.445–2.197

0.000

1.450

1.144–1.837

0.002

Experience of abortion or miscarriage

No

–

–

–

–

–

Yes

1.363–2.290

0.000

1.183

0.882–1.585

0.262

Menstrual cycle

Regular

–

–

–

–

–

Variable length ≥ 7-day difference

0.991–1.947

0.056

1.536

1.076–2.193

0.018

Interval of amenorrhea of ≥ 60 days

0.849–2.226

0.196

1.430

0.848–2.409

0.179

Age of partner (years)

18–29

–

–

–

–

–

30–39

1.295–2.146

0.000

1.326

0.973–1.806

0.074

40–49

1.955–3.649

0.000

1.519

1.030–2.240

0.035

50–64

1.207–5.301

0.014

1.201

0.525–2.747

0.665

Body mass index of partner (kg/m²)

 < 18.5

–

–

–

–

–

18.5–24.9

0.447–1.264

0.282

0.727

0.408–1.295

0.279

25–29.9

0.508–1.512

0.635

0.759

0.414–1.392

0.373

 ≥ 30

0.715–2.812

0.318

1.187

0.560–2.520

0.655

Smoking of partner

Never or former smoker

–

–

–

–

–

Current smoker

1.219–1.840

0.000

1.383

1.088–1.759

0.008