Table 2.

Mean unadjusted change within individuals in cycle length and menses length, and adjusted difference in the change from three prevaccination cycle average to first or second vaccination cycle and cycle after the second vaccination cycle

Outcome per cycle	Unvaccinated		Vaccinated		Adjusted difference in change (days; 99.3% CI)*
	No	Unadjusted change from prevaccination average (99.3% CI)	No	Unadjusted change from prevaccination average (99.3% CI)
Cycle length
First dose	4686	0.09 (–0.08 to 0.27)	14 936	0.81 (0.68 to 0.93)	0.71 (0.47 to 0.96)
Second dose	4423	0.21 (0.02 to 0.39)	9600	0.76 (0.60 to 0.93)	0.56 (0.28 to 0.84)
Cycle after second dose	4134	0.20 (0.01 to 0.39)	8871	0.09 (–0.03 to 0.20)	–0.11 (–0.33 to 0.10)
Menses length
First dose	4686	–0.06 (–0.12 to 0.00)	14 560	0.01 (–0.02 to 0.04)	0.07 (0.00 to 0.13)
Second dose	4423	−0.10 (–0.15 to –0.04)	9085	0.03 (–0.01 to 0.07)	0.13 (0.06 to 0.20)

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.