Table 1 Baseline (T1) characteristics of all T1 participants by premenstrual syndrome
|  | None to mild (n = 2593) | Moderate to severe (n = 497) | P |
|---|---|---|---|
Demographics | |||
 Age, median (IQR) | 35 (30–40) | 33 (29–38) |  < 0.001 |
 Married (n, %) | 1275 (49.2) | 241 (48.5) | 0.78 |
 Having a child (n, %) | 1065 (41.1) | 182 (36.6) | 0.06 |
 University education (n, %) | 1314 (50.7) | 220 (44.3) | 0.009 |
 Annual household income (n, %) | |||
    < 4 million JPY | 682 (26.3) | 152 (30.6) | 0.14 |
    ≥ 4 & < 6 million JPY | 586 (22.6) | 109 (21.9) |  |
    ≥ 6million JPY | 766 (29.5) | 141 (28.4) |  |
   Unknown | 559 (21.6) | 95 (19.1) |  |
 Living in densely populated area (n, %)a | 1489 (57.4) | 274 (55.1) | 0.34 |
Lifestyles | |||
 Current smoker (n, %) | 305 (11.8) | 71 (14.3) | 0.12 |
 Habitual drinker (n, %) | 485 (18.7) | 107 (21.5) | 0.14 |
 Working hours per week (median, IQR) | 38 (20–40) | 35 (20–40) | 0.95 |
     ≥ 38 h/week (n, %) | 1317 (50.8) | 244 (49.1) | 0.49 |
Total scores on the Menstrual Distress Questionnaire, median (IQR) | |||
 Premenstrual score | 20 (9–38) | 57 (42–74) |  < 0.001 |
 Menstrual score | 15 (7–32) | 54 (35–74) |  < 0.001 |
 Intermenstrual score | 4 (1–11) | 23 (10–48) |  < 0.001 |
WHO Health and Work Performance Questionnaire, median (IQR) | |||
 Absolute absenteeism | 0 (− 7 to 18) | 0 (− 10 to 22) | 0.34 |
 Relative absenteeism | 0 (− 0.05 to 0.125) | 0 (− 0.08 to 0.225) | 0.33 |
 Absolute presenteeism (0–100) | 60 (50–70) | 50 (40–70) |  < 0.001 |
 Relative presenteeism (0.25–2.0) | 1 (1–1) | 1 (0.83–1) | 0.07 |