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. 2019 Nov;112(5):892-899.
doi: 10.1016/j.fertnstert.2019.06.036.

Fecundability in relation to use of fertility awareness indicators in a North American preconception cohort study

Joseph Barney Stanford  1 , Sydney Kaye Willis  2 , Elizabeth Elliott Hatch  2 , Kenneth Jay Rothman  3 , Lauren Anne Wise  2
Affiliations

Fecundability in relation to use of fertility awareness indicators in a North American preconception cohort study

Joseph Barney Stanford et al. Fertil Steril. 2019 Nov.

Abstract

Objective: To quantify the frequency of use of selected fertility awareness indicators and to assess their influence on fecundability.

Design: Web-based prospective cohort study.

Setting: Not applicable.

Patient(s): Female pregnancy planners, aged 21-45 years, attempting conception for ≤6 cycles at study entry.

Intervention(s): None.

Main outcome measure(s): We ascertained time to pregnancy, in menstrual cycles, with bimonthly questionnaires. We estimated adjusted fecundability ratios (FRs) and confidence intervals (CIs) using proportional probabilities models, controlling for age, income, education, smoking, intercourse frequency, and other lifestyle and reproductive factors.

Result(s): A total of 5,688 women were analyzed, with a mean age of 29.9 years and mean time trying of 2.1 cycles at baseline; 30% had ever been pregnant. At baseline, 75% were using one or more fertility indicators (counting days or charting menstrual cycles [71%], measuring basal body temperature [BBT, 21%], monitoring cervical fluid [39%], using urine LH tests [32%], or feeling for changes in position of the cervix [12%]). Women using any fertility indicator at baseline had higher subsequent fecundability (adjusted FR 1.25, 95% CI 1.16-1.35) than those not using any fertility indicators. For each individual indicator, adjusted FRs ranged from 1.28-1.36, where 1.00 would indicate no relation with fecundability. The adjusted FR for women using a combination of charting days, cervical fluid, and urine LH was 1.48 (95% CI 1.31-1.67) relative to women using no fertility indicators.

Conclusion(s): In a North American preconception cohort study, use of fertility indicators indicating the fertile window was common, and was associated with greater fecundability.

Keywords: Fertility awareness; cohort studies; fertility; preconception; time to pregnancy.

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Conflict of interest statement

Conflict of Interest Disclosures: Drs. Hatch, Wise, Rothman, and Stanford and Ms. Willis report grants from National Institutes of Health during the conduct of the study. Dr. Wise reports in-kind donations from FertilityFriend.com (fertility apps for PRESTO), Swiss Precision Diagnostics (home pregnancy tests for PRESTO), and Sandstone Diagnostics (semen test kits for PRESTO) during the conduct of the study. Dr. Stanford reports personal fees from Swiss Precision Diagnostics, outside the submitted work; and is an unpaid member of Boards for two organizations that educate health professionals about fertility awareness methods: the International Institute for Restorative Reproductive Medicine (Board of Directors), and the Fertility Appreciation Collaborative to Teach the Science (Advisory Board).

Figures

Figure 1.
Figure 1.
Prevalence of reported use of individual fertility indicators at baseline and bimonthly follow-up questionnaires.
See this image and copyright information in PMC

Comment in

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