Table 4.

Independent factors associated with either a short (1–3 days) or long (8+ days) duration of menstrual bleeding compared to an average duration (4–7 days), from logistic regression using backward elimination

Factor	Short period vs. average duration: 1252 observations – 145 short and 1107 normal – from 649 women Odds ratio (95% CI)	Long period vs. average duration: 1346 observations – 239 long and 1107 normal – from 669 women Odds ratio (95% CI)
Baseline ovulatory status/concurrent ovulatory status:
Ovulatory – Ovulatory	Reference	Reference
Ovulatory – Anovulatory	1.78 (0.79, 4.02)	3.92 (2.25, 6.81)
Anovulatory – Ovulatory	0.72 (0.15, 3.48)	2.26 (0.90, 5.68)
Anovulatory – Anovulatory	2.36 (1.22, 4.59)	2.46 (1.41, 4.27)
Baseline fibroids	--(a)	1.46 (1.01, 2.13)

^(a)Excluded from model using backward elimination