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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. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study is to evaluate socioeconomic determinants of fecundability., Methods: Among 8654 female pregnancy planners from Pregnancy Study Online, a North American prospective cohort study (2013-2019), we examined associations between socioeconomic status and fecundability (the per-cycle probability of conception). Information on income and education was collected via baseline questionnaires. Bimonthly follow-up questionnaires were used to ascertain pregnancy status. We estimated fecundability ratios (FRs) and 95% confidence intervals (CIs) using proportional probabilities regression, controlling for potential confounders., Results: Relative to an annual household income of greater than or equal to $150,000, adjusted FRs were 0.91 (95% CI: 0.83-1.01) for less than $50,000, 0.99 (95% CI: 0.92-1.07) for $50,000-$99,000, and 1.09 (95% CI: 1.01-1.18) for $100,000-$149,000. FRs for less than 12, 13-15, and 16 years of education, relative to greater than or equal to 17 years, were 0.90 (95% CI: 0.76-1.08), 0.84 (95% CI: 0.78-0.91), and 0.89 (95% CI: 0.84-0.95), respectively. Slightly stronger associations for income and education were seen among older women., Conclusions: Lower levels of education and income were associated with modestly reduced fecundability. These results demonstrate the presence of socioeconomic disparities in fecundability., (Copyright © 2020 Elsevier Inc. All rights reserved.)