Mean unadjusted within-individual change in cycle length, and adjusted difference in the change from three prevaccination cycle average to first or second vaccination cycle and cycle following the second vaccination cycle, stratified by the number of doses received in a single cycle
| Doses per cycle | Unvaccinated | Vaccinated | Adjusted difference in change (days; 99.3% CI)* | ||
| No | Unadjusted change from prevaccination average (days; 99.3% CI) | No | Unadjusted change from prevaccination average (days; 99.3% CI) | ||
| One dose per cycle | |||||
| First dose | 4686 | 0.09 (−0.08 to 0.27) | 14 193 | 0.64 (0.53 to 0.76) | 0.55 (0.33 to 0.77) |
| Second dose | 4423 | 0.21 (0.02 to 0.39) | 8857 | 0.50 (0.36 to 0.64) | 0.29 (0.06 to 0.53) |
| Cycle after second dose | 4134 | 0.20 (0.01 to 0.39) | 8169 | 0.02 (−0.10 to 0.14) | −0.18 (−0.39 to 0.03) |
| Two doses per cycle | |||||
| First and second dose | 4686 | 0.21 (0.02 to 0.39) | 743 | 3.91 (2.53 to 5.28) | 3.70 (2.98 to 4.42) |
| Cycle after first and second dose | 4134 | 0.20 (0.01 to 0.39) | 702 | 0.85 (0.24 to 1.46) | 0.65 (0.13 to 1.18) |
Data are mean (99.3% confidence interval), unless otherwise stated. CI=confidence interval.
*Differences between groups come from mixed effects models with random intercepts and slopes at the individual level, an interaction between vaccination status and before and after vaccination timing, and are adjusted for age, body mass index, educational attainment, parity, relationship status, and global region.