Menstrual Cycle Characteristics of U. S. Adolescents According to Gynecologic Age and Age at Menarche

Kim G Harley; Annalisa Watson; Samantha Robertson; Virginia J Vitzthum; Amanda Shea

doi:10.1016/j.jpag.2024.03.005

Menstrual Cycle Characteristics of U. S. Adolescents According to Gynecologic Age and Age at Menarche

J Pediatr Adolesc Gynecol. 2024 Apr 1:S1083-3188(24)00206-7. doi: 10.1016/j.jpag.2024.03.005. Online ahead of print.

Authors

Kim G Harley¹, Annalisa Watson², Samantha Robertson³, Virginia J Vitzthum⁴, Amanda Shea⁵

Affiliations

¹ Wallace Center for Maternal, Child, and Adolescent Health, School of Public Health, University of California, Berkeley, California. Electronic address: kharley@berkeley.edu.
² Wallace Center for Maternal, Child, and Adolescent Health, School of Public Health, University of California, Berkeley, California.
³ Department of Electrical Engineering and Computer Science, University of California, Berkeley.
⁴ Department of Medicine, University of British Columbia, Canada; Indiana University, Bloomington, Indiana.
⁵ Clue, Berlin, Germany.

PMID: 38570085
DOI: 10.1016/j.jpag.2024.03.005

Abstract

Study objective: To characterize typical menstrual cycle characteristics in adolescents and determine how these differ with age at menarche or years since menarche (gynecologic age).

Methods: We surveyed 13 to 18-year-old U.S. users of the Clue app (N = 6,486) and linked their responses to app-recorded cycle data (N=38,916 cycles). We analyzed cycle characteristics including cycle length, cycle variability, period length, experience of heavy flow, and dysmenorrhea in relation to gynecologic age and menarcheal age using mixed effects models.

Results: With increasing gynecologic age, we observed dose-dependent associations of lower odds of cycle irregularity (defined as cycles that were highly variable, short, or long) and higher odds of reporting ≥1 day of heavy flow. Individuals <1 year post-menarche had lower odds of heavy flow (Odds Ratio (OR) = 0.3; 95% confidence interval (CI): 0.1, 0.6), and increased odds of having a highly variable cycle (OR = 2.6; 95% CI: 1.3, 5.2) or short cycles (OR = 5.0; 95% CI: 2.3, 11.0) compared to those who were 6+ years post-menarche. We also found associations with early and late age at menarche. Compared to menarcheal age of 14+ years, menarcheal age ≤10 years was associated with shorter cycle length (β = -1.63 days; 95% CI: -2.51, -0.75), increased odds of dysmenorrhea (OR = 3.2; 95% CI: 2.3, 4.6), and decreased odds of high cycle variability (OR = 0.8; 95% CI: 0.6, 1.0).

Conclusion: Cycle characteristics in adolescence are associated with menarcheal age and gynecologic age. Notably, highly variable cycles are common, especially among those with younger gynecologic age or older menarcheal age.

Keywords: Adolescents; Age at menarche; Menstrual cycle.