Table 3.
Correlates of long menstrual flow duration compared with normal menstrual flow duration among nulliparous Danish women in the Snart-Gravid study (n = 1,940*)
| Menstruation duration (≥5 days), n (%) | Prevalence ratio† | 95% CI | |
|---|---|---|---|
| Age (years) | |||
| <25 | 158 (38.9) | 1.00 | (reference) |
| 25–29 | 326 (35.9) | 0.93 | 0.80–1.09 |
| 30–34 | 132 (32.7) | 0.86 | 0.71–1.04 |
| 35–40 | 16 (21.3) | 0.55 | 0.34–0.87 |
| BMI (kg/m2) | |||
| <20 | 113 (41.4) | 1.21 | 1.03–1.43 |
| 20–24 | 338 (33.0) | 1.00 | (reference) |
| 25–29 | 114 (34.7) | 1.03 | 0.87–1.22 |
| ≥30 | 67 (40.6) | 1.17 | 0.95–1.45 |
| Physical activity (METs) | |||
| <5 | 25 (39.7) | 1.22 | 0.88–1.69 |
| 5–9 | 54 (38.6) | 1.14 | 0.90–1.45 |
| 10–19 | 195 (37.9) | 1.21 | 1.04–1.42 |
| 20–39 | 219 (31.1) | 1.00 | (reference) |
| ≥40 | 139 (37.5) | 1.21 | 1.02–1.44 |
| Alcohol (drinks/week) | |||
| Does not drink | 207 (41.0) | 1.00 | (reference) |
| 1–2 | 189 (35.9) | 0.87 | 0.75–1.02 |
| 3–6 | 175 (31.7) | 0.78 | 0.66–0.92 |
| 7–13 | 47 (27.5) | 0.69 | 0.53–0.91 |
| ≥14 | 14 (38.9) | 0.95 | 0.62–1.46 |
| Smoking (cigarettes/day) | |||
| Does not smoke | 517 (35.2) | 1.00 | (reference) |
| <1 | 37 (35.2) | 1.09 | 0.83–1.43 |
| 1–9 | 29 (31.2) | 0.87 | 0.64–1.19 |
| ≥10 | 49 (38.9) | 1.08 | 0.86–1.37 |
| Caffeine (mg/day) | |||
| <100 | 374 (36.2) | 1.00 | (reference) |
| 100–199 | 134 (34.8) | 1.04 | 0.88–1.22 |
| 200–299 | 65 (32.0) | 1.00 | 0.81–1.25 |
| ≥300 | 59 (34.3) | 1.13 | 0.90–1.43 |
Notes:
*
We excluded women with missing information on duration of menstruation (n = 3) and with missing covariate information (n = 145);
†
mutually adjusted for all other covariates and most recent method of birth control.
Abbreviations: n, number; CI, confidence interval; BMI, body mass index; METs, metabolic equivalents.