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Paediatric and Perinatal Epidemiology, 38(8), 641-650, 2024

The association between the use of fertility indicators and fecundability in a Danish preconception cohort

Elizabeth E Hatch , Anne Sofie Dam Laursen , Ellen M Mikkelsen

Author affiliations (4)
  • Department of Epidemiology Boston University School of Public Health Boston MA USA ROR
  • Department of Clinical Epidemiology, Aarhus University Hospital Aarhus University Aarhus N Denmark ROR
  • University of Utah ROR
  • Slone Epidemiology Center at Boston University, Boston, Massachusetts and 2Lombardi Comprehensive Cancer Center at Georgetown University Medical Center, Washington, District of Columbia ROR
DOI10.1111/ppe.13108 PMID39109606
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Abstract

Background

The use of fertility indicators to predict ovulation has largely been studied for contraceptive purposes, while less so as fertility-promoting tools.

Objective

To investigate the association between fertility indicators and fecundability in Danish women trying to conceive.

Methods

Web-based preconception cohort study. We analysed data from 11,328 females aged 18-49 years trying to conceive without fertility treatment for ≤6 menstrual cycles, from the Danish SnartGravid.dk and SnartForældre.dk cohorts (2007-2023). Participants reported the use of fertility indicators (counting days since the last menstrual period, cervical fluid monitoring, urinary ovulation testing, feeling ovulation, using a smartphone fertility app and measuring basal body temperature [BBT]). Time to pregnancy was measured in menstrual cycles ascertained by self-reported pregnancy status. We estimated fecundability ratios (FR) and 95% confidence intervals (CI) using proportional probabilities regression models adjusted for age, socio-economic position, health indicators, reproductive history and gynaecological factors.

Results

Fertility indicators were used by 63.3% of participants at study entry. Counting days was the most common (46.9%), while measuring BBT was the least (3.0%). Other indicators ranged from 17.0% to 23.6%, with 69.7% using more than one indicator. Compared with non-use, use of any fertility indicator was associated with greater fecundability (adjusted FR 1.14, 95% CI 1.08, 1.19). Cervical fluid monitoring showed the strongest association (aFR 1.46, 95% CI 1.03, 2.07), followed by urinary ovulation testing (aFR 1.35, 95% CI 1.16, 1.58) and counting days (aFR 1.18, 95% CI 1.09, 1.29). Feeling ovulation and fertility apps were modestly associated with fecundability, while measuring BBT was not associated. Sensitivity analysis restricting to ≤2 cycles of attempt time and two cycles of follow-up showed an aFR for any indicator use of 1.21 (95% CI 1.13, 1.31).

Conclusion

In this Danish preconception cohort, use of fertility indicators was associated with a higher fecundability, varying by type of indicator.

Topics

Fertility Awareness > Methods > Effectiveness for ConceptionFertility Awareness > Biomarkers > Multiple Indicator ComparisonResearch Methodology > Cohort Studies > Preconception Danish
fertility indicators fecundability Danish preconception cohort, ovulation detection methods time to pregnancy Denmark, Pedersen Mikkelsen Stanford fertility indicator use TTP, cervical mucus BBT OPK fecundability association, fertility awareness method use pregnancy planning outcomes, Paediatric Perinatal Epidemiology fertility indicators 2024, preconception fertility monitoring behavior pregnancy rate, timed intercourse fertility indicator Danish women, Rothman Wise Hatch Snart Gravid fertility cohort
PMID 39109606 39109606 DOI 10.1111/ppe.13108 10.1111/ppe.13108

Cite this article

Pedersen, E. S., Mikkelsen, E. M., Sørensen, H. T., Hatch, E. E., Wise, L. A., Rothman, K. J., Stanford, J. B., & Laursen, A. S. D. (2024). The association between the use of fertility indicators and fecundability in a Danish preconception cohort. *Paediatric and perinatal epidemiology*, *38*(8), 641-650. https://doi.org/10.1111/ppe.13108

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