Menstrual cycle characteristics and fecundability in a North American preconception cohort

Amelia K Wesselink; Lauren A Wise; Elizabeth E Hatch; Kenneth J Rothman; Ellen M Mikkelsen; Joseph B Stanford; Craig J McKinnon; Shruthi Mahalingaiah

doi:10.1016/j.annepidem.2016.05.006

Menstrual Cycle Cycle Across the Lifespan

Menstrual cycle characteristics and fecundability in a North American preconception cohort

Wesselink AK, Wise LA, Hatch EE, Rothman KJ, Mikkelsen EM, Stanford JB, McKinnon CJ, Mahalingaiah S

Published July 2016 Annals of epidemiology, 26(7), 482-487.e1

DOI 10.1016/j.annepidem.2016.05.006 PMID 27449569 PMC PMC4964792

RRM Academy Synopsis

First period before age 12 linked to a lower monthly pregnancy chance

Among pregnancy planners, a first period before age 12 went with a slightly lower chance of pregnancy each cycle (ratio 0.87, 95% CI: 0.76–0.99). The online cohort included 2,189 women in North America. Cycles under 25 days had a ratio of 0.81 (95% CI: 0.54–1.22).

Key Findings

Menarche before age 12 gave an adjusted fecundability ratio of 0.87 (95% CI: 0.76–0.99) against menarche at 12–13 years, across 2,542 cycles and 287 pregnancies.
Usual cycle length under 25 days gave an adjusted ratio of 0.81 (95% CI: 0.54–1.22), and 25–26 days gave 0.92 (95% CI: 0.75–1.14), against 27–29 days.
Women whose cycles did not become regular after menarche had an adjusted ratio of 0.93 (95% CI: 0.81–1.06) against women whose cycles regularized within 2 years.
Bleed length was not appreciably associated with fecundability. Heavy bleeds gave an adjusted ratio of 0.85 (95% CI: 0.58–1.24), which the authors call imprecise.
The early-life analysis covered 2,189 women with 9,832 cycles and 1,355 pregnancies. The cycle-length analysis covered 1,260 regularly cycling women with 5,719 cycles and 777 pregnancies.

Interpretation

This cohort study followed pregnancy planners enrolled in PRESTO, an internet-based study in the United States and Canada. Participants were aged 21–45, in a stable relationship with a male partner, and had tried to conceive for 6 cycles or fewer at entry. Earlier menarche and shorter usual cycle length were each linked with lower fecundability, and cycles of 34 days or longer gave a ratio of 1.25 (95% CI: 0.96–1.62). The authors note that cycle history came from participants' own reports. The findings support larger studies of menstrual cycle characteristics and fertility.

RRM Context

Restorative reproductive medicine reads the cycle as a vital sign. This cohort adds data on cycle features and time to pregnancy. The authors suggest menarche before age 12 and short cycles may signal lower fertility potential. Prospective Fertility Friend charting gave cycle lengths averaging 2.0 days longer than women reported at baseline (SD=4.2, 73 women).

Our editorial summary of this paper, not the article's abstract.

Abstract

Purpose

The aim of this study was to evaluate the association between menstrual cycle characteristics in early life and adulthood and fecundability.

Methods

Pregnancy Study Online (PRESTO) is an Internet-based preconception cohort study of pregnancy planners from the United States and Canada. During the preconception period, we enrolled 2189 female pregnancy planners aged 21-45 years who had been attempting conception for ≤6 cycles. Women self-reported menstrual cycle characteristics via an online baseline questionnaire, and pregnancy status was ascertained through bimonthly follow-up questionnaires. Proportional probabilities models were used to estimate fecundability ratios (FRs) and 95% confidence intervals (CIs), adjusting for potential confounders.

Results

Compared with usual menstrual cycle lengths of 27-29 days, cycle lengths of <25 (FR = 0.81, 95% CI: 0.54-1.22) and 25-26 days (FR = 0.92, 95% CI: 0.75-1.14) were associated with reduced fecundability. Compared with women who reached menarche at the age of 12-13 years, those who reached menarche at <12 years had reduced fecundability (FR = 0.87, 95% CI: 0.76-0.99). Women whose cycles never regularized after menarche (FR = 0.93, 95% CI: 0.81-1.06) had slightly reduced fecundability compared with women whose cycles regularized within 2 years of menarche. Bleed length and heaviness of bleeding were not appreciably associated with fecundability.

Conclusions

Menstrual cycle characteristics, specifically cycle length and age at menarche, may act as markers of fertility potential among pregnancy planners.

Topics

Menstrual Cycle Cycle Across the Lifespan Adolescent Cycles

Menstrual Cycle › Cycle Across the Lifespan › Adolescent Cycles

Amelia K Wesselink, Lauren A Wise, Elizabeth E Hatch, Kenneth J Rothman, Ellen M Mikkelsen, Joseph B Stanford, Craig J McKinnon, Shruthi Mahalingaiah

A Wesselink, L Wise, Liz Hatch, Beth Hatch, Betsy Hatch, E Hatch, Ken Rothman, K Rothman, E Mikkelsen, Joe Stanford, Joey Stanford, J Stanford, C McKinnon, S Mahalingaiah

PMID 27449569 27449569 DOI 10.1016/j.annepidem.2016.05.006 10.1016/j.annepidem.2016.05.006 Wesselink et al. 2016, Wesselink 2016

Menstrual cycle characteristics and fecundability in a North American preconception cohort

First period before age 12 linked to a lower monthly pregnancy chance

Key Findings

Interpretation

RRM Context

Abstract

Topics

By this author

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