Table 2.

ORs and 95% CIs of change in menstrual cycle characteristics concerning SARS-CoV-2 infection and COVID-19 vaccination status, the Nurses’ Health Study 3 (N=3116)

Change in usual menstrual characteristics	SARS-CoV-2 infectiona n=349 OR (95% CI)	COVID-19 vaccinationb n=2835 OR (95% CI)
Change in cycle length or regularity
Any change (n=2227)	0.84 (0.66–1.08)	1.10 (0.84–1.45)
Change in cycle length
Any change (n=1408)	0.89 (0.71–1.12)	1.27 (0.98–1.65)
Change in cycle lengthc
Shorter (n=858)	0.89 (0.68–1.16)	1.17 (0.88–1.57)
Longer (n=550)	0.89 (0.64–1.22)	1.48 (1.00–2.19)
Change in cycle regularity
Any change (n=1735)	0.90 (0.72–1.14)	0.86 (0.67–1.12)
Change in cycle regularityc
More regular (n=709)	0.81 (0.60–1.10)	0.89 (0.65–1.22)
Less regular (n=1026)	0.97 (0.74–1.27)	0.83 (0.61–1.12)

Change in cycle characteristics was defined by change in 3 categories: cycle regularity ([1] very regular [±3 days], [2] regular [within 5–7 days], or [3] usually irregular or always irregular or no period) and cycle length ([1] <26 days, [2] 26–31 days, or [3] ≥32 days). Models were adjusted for age at baseline, follow-up time, body mass index at end of follow-up, weight change, race and ethnicity, educational attainment, region, and mutually adjusting for SARS-CoV-2 infection and vaccination. Of note, 742 hormonal contraception users at MOD2 were excluded from the analysis.

CI, confidence interval; OR, odds ratio.

Wang. COVID-19 infection and vaccination and menstrual cycle changes. Am J Obstet Gynecol 2022.

^aReference: uninfected

^bReference: unvaccinated

^cMultinomial logistic model.