Table 1

Basic characteristics of study participants (n=32 748)

Number (percentage)Mean±SDMedian
Age, years28.6±8.628
 15–196141 (18.8)
 20–246118 (18.7)
 25–295825 (17.8)
 30–345483 (16.7)
 35–404687 (14.3)
 41–454494 (13.7)
Level of education
 Low4020 (12.3)
 Medium12 335 (37.9)
 High16 229 (49.8)
Hours/week
 Paid work21.7±14.724
 Study7.4±13.60
 Voluntary work0.8±3.10
Menstrual cycle
 Regular cycle25 717 (78.5)
  Duration28.8±3.028
 Amenorrhoea due to LG-IUD/OC3675 (11.2)
 Irregular, variation >10 days per cycle2495 (7.6)
 Do not know861 (2.6)
 Days with blood loss per cycle5.4±1.65
Visited a doctor for MRSs
 No17 873 (54.6)
 Yes, general practitioner10 141 (31.0)
 Yes, gynaecologist4698 (14.4)
Diagnosis for MRSs*
 No29 731 (90.8)
 Yes3017 (9.2)
  Endometriosis1120 (3.4)
  PCOS588 (1.8)
  Adenomyosis103 (0.3)
  Fibroids275 (0.8)
  Other1901 (5.8)
Contraception*
 Hormonal contraception11 993 (36.6)
  OC8650 (26.4)
  LG-IUD2752 (8.4)
  Other hormonal: injection, transdermal and so on882 (2.7)
 No hormonal contraception20 755 (63.4)
  Cu-IUD771 (2.4)
  Female sterilisation423 (1.3)
  No female contraception19 639 (60.0)
Nulliparous21 585 (66.0)
Paid work >5 hours a week26 104 (79.7)
 Age29.7±8.329
 Hours of paid work/week27.0±11.428
 Hours spent on study/week7.5±13.40
 >40 hours of paid work/week1047 (3.2)
Study >5 hours a week8764 (26.8)
 Age22.0±6.220
 Hours spent on study/week27.4±12.130
 Hours of paid work/week15.5±11.312
 >40 hours spent on study/week322 (1.0)
  •  Mean duration of cycle based on women with a regular cycle.

  • *More than one answer possible.

  • Cu-IUD, copper intrauterine device; LG-IUD, levonorgestrel-releasing intrauterine device; MRSs, menstruation-related symptoms; PCOS, polycystic ovary syndrome; OC, oral contraceptive.