Table 4

 Odds ratio (OR) and 95% confidence interval (CI) for dysmenorrhoea in association with self perceived stress in the preceding menstrual cycle and a reported history of dysmenorrhoea at baseline

History of dysmenorrhoea‡Stress in the preceding cyclesTotal cycles (% dysmenorrhoea)OR†§95% CI§
†The outcome was defined as a binary variable adjusted for age, BMI, shift work, dust exposure, cycle length, education, and passive smoking.
‡History of dysmenorrhoea refers to experience of dysmenorrhoea within a year prior to enrolment, obtained from baseline questionnaire.
§OR, odds ratio; CI, confidence interval.
¶Reference group.
NoLow257 (10.9)1.0¶
NoMedium243 (17.3)1.30.7 to 2.2
NoHigh73 (24.7)2.10.9 to 5.2
YesLow237 (33.8)4.22.3 to 7.6***
YesMedium252 (39.7)4.62.6 to 8.3***
YesHigh98 (58.2)10.44.9 to 22.3***