Table 2. Original and derived G0 cycle length variables (N (%)).
| Question | 28.6 years | 37.8 years | 40.3 years | 49.7 years | 51.3 years |
|---|---|---|---|---|---|
| Original variables | |||||
| If regular, how many days were there from the start of one period to the start of the next one? | |||||
| Mean (SD) | 27.54 (3.85) | 25.90 (6.36) | 25.73 (6.57) | - | - |
| < 15 days * | 107 (1.16) | 419 (7.24) | 388 (7.46) | - | - |
| 15–20 days * | 50 (0.54) | 47 (0.81) | 45 (0.87) | - | - |
| 21–25 days * | 1218 (13.15) | 873 (15.08) | 831 (15.98) | - | - |
| 26–30 days * | 7072 (76.35) | 4103 (70.89) | 3689 (70.96) | - | - |
| 31–35 days * | 747 (8.07) | 322 (5.56) | 226 (4.35) | - | - |
| 36–40 days * | 42 (0.45) | 16 (0.28) | 9 (0.17) | - | - |
| > 40 days * | 26 (0.28) | 8 (0.14) | 11 (0.21) | - | - |
| Are your periods regular? | |||||
| Yes, every 23 days or less | - | - | - | 283 (10.98) | - |
| Yes, between 24 and 35 days | - | - | - | 1420 (55.10) | - |
| Yes, more than every 35 days | - | - | - | 86 (3.34) | - |
| No | - | - | - | 788 (30.58) | - |
|
In the years before your last period, how many days do you usually have between the start of one period and
the start of the next period? | |||||
| Less than 21 days | - | - | - | - | 329 (11.14) |
| 21–25 days | - | - | - | - | 594 (20.12) |
| 26–31 days | - | - | - | - | 1066 (36.11) |
| 32–39 days | - | - | - | - | 161 (5.45) |
| 40–50 days | - | - | - | - | 78 (2.64) |
| More than 50 days | - | - | - | - | 96 (3.25) |
| Too irregular to estimate | - | - | - | - | 628 (21.27) |
| Derived variables | |||||
| Normal (24–38 days) | 8246 (89.03) | 4846 (83.72) | 4331 (83.30) | - | - |
| Frequent (<24 days) | 978 (10.56) | 926 (16.00) | 852 (16.39) | - | - |
| Infrequent (>38 days) | 38 (0.41) | 16 (0.28) | 16 (0.31) | - | - |
*Continuous responses recoded.