Table 3.

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.