Time to Pregnancy for Women Using a Fertility Awareness Based Mobile Application  to Plan a Pregnancy

Favaro C, Pearson JT, Rowland SP, Jukic AM, Chelstowska M, Berglund Scherwitzl E, Scherwitzl R, Gemzell Danielsson K, Harper J

doi:10.1089/jwh.2021.0026

Journal of Women's Health (2002), 30(11), 1538-1545, 2021

Time to Pregnancy for Women Using a Fertility Awareness Based Mobile Application to Plan a Pregnancy

Simon P Rowland , Anne Marie Z. Jukic , Berglund Scherwitzl E

Author affiliations (4)

Natural Cycles USA Corp, New York, New York, USA. ROR
National Institute of Environmental Health Sciences ROR
Karolinska University Hospital ROR
Institute for Reproductive Health ROR

DOI10.1089/jwh.2021.0026 PMID34495761

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Abstract

Background

Time to pregnancy (TTP) is a biomarker of fecundability and has been associated with behavioral and environmental characteristics; however, these associations have not been examined in a large population-based sample of application (app) users.

Materials and Methods

This observational study followed 5,376 women with an age range of 18 to 45 years who used an app to identify their fertile window. We included women who started trying to conceive between September 30, 2017 and August 31, 2018. TTP was calculated as the number of menstrual cycles from when the user switched to "Plan" mode up to and including the cycle in which they logged a positive pregnancy test. We examined associations with several characteristics, including age, gravidity, body mass index, cycle length and cycle length variation, frequency of sexual intercourse, and temperature measuring frequency. Discrete time fecundability models were used to estimate fecundability odds ratios.

Results

For the complete cohort the 6-cycle and 12-cycle cumulative pregnancy probabilities were found to be 61% (95% confidence interval [CI]: 59-62) and 74% (95% CI: 73-76), respectively. The median TTP was four cycles. The highest fecundability was associated with an age of less than 35 years, with cycle length variation <5 days and logging sexual intercourse on at least 20% of days added (the proportion of days in which intercourse was logged) (11.5% [n = 613] of entire sample). This group achieved a 6and 12-cycle cumulative pregnancy probability of 88% (95% CI: 85-91) and 95% (95% CI: 94-97), respectively, and a TTP of 2 cycles.

Conclusions

Natural Cycles was an effective method of identifying the fertile window and a noninvasive educational option for women planning a pregnancy. Women under age 35 with regular cycles showed a high pregnancy rate.

Topics

fertility-awareness/effectiveness/fertile-window-estimation menstrual-cycle/cycle-biomarkers/basal-body-temperature

time to pregnancy fertility app, fertility awareness mobile application, fecundability biomarker app-based, TTP behavioral characteristics, digital fertility tracking outcomes, ovulation prediction app study, natural conception fertility tracking, app-based family planning effectiveness, demographic factors time to pregnancy, environmental exposures fecundability

PMID 34495761 34495761 DOI 10.1089/jwh.2021.0026 10.1089/jwh.2021.0026 Favaro et al. 2021, Favaro 2021

Cite this article

Favaro, C., Pearson, J. T., Rowland, S. P., Jukic, A. M., Chelstowska, M., Berglund Scherwitzl, E., Scherwitzl, R., Gemzell Danielsson, K., & Harper, J. (2021). Time to Pregnancy for Women Using a Fertility Awareness Based Mobile Application to Plan a Pregnancy. Journal of women's health (2002), 30(11), 1538-1545. https://doi.org/10.1089/jwh.2021.0026

fertility-awareness/effectiveness/fertile-window-estimation menstrual-cycle/cycle-biomarkers/basal-body-temperature Open Access

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

Pedersen ES et al., 2024 Paediatr Perinat Epidemiol

The use of fertility indicators to predict ovulation has largely been studied for contraceptive purposes, while less so as fertility-promoting tools. To investigate the association between fertility indicators and fecundability in Danish women trying to conceive. 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. 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). In this Danish preconception cohort, use of fertility indicators was associated with a higher fecundability, varying by type of indicator.

fertility-awareness/effectiveness/fertile-window-estimation diagnostics/cycle-biomarkers/temperature-trackingmenstrual-cycle/cycle-biomarkers/basal-body-temperature

Basal body temperature assessment: is it useful to couples seeking pregnancy?

Barron ML et al., 2005 MCN Am J Matern Child Nurs

Advanced practice nurses in primary care settings are often asked to give appropriate advice to couples seeking pregnancy. This article examines the issue of basal body temperature (BBT), a time-honored way to establish the presence of ovulatory cycles, and asks if BBT is an outdated recommendation. The article also reviews the benefits and limitations of recommending BBT to couples seeking pregnancy in light of recent fecundity research.

gynecology/breast-health/benign-breast-conditions reproductive-endocrinology/ovarian-hormones/progesteronemenstrual-cycle/cycle-biomarkers/basal-body-temperature Open Access

MON-154 Breast areolar diameter in healthy menstruating women—a single cycle cross-sectional study of associations with body size and ovulatory characteristics

Baaske AV et al., 2025 Journal of the Endocrine Society

A.V. Baaske: None. S. Shirin: None. C. Bos: None. D. Kalidasan: None. J.C. Prior: None. Tanner Breast Stage 3 (TB3, at menarche) and Tanner 5 (TB5, once ovulatory cycles established), despite being similar with an “upstanding” nipple, are different. Evidence suggests that steady and high ovulatory-level progesterone exposure accounts for the larger areolar diameter in TB5. Progesterone levels indicate whether the menstrual cycle is ovulatory and have crucial implications for women’s reproductive, metabolic, cardiovascular, and bone health. However, few data show average areolar diameter in regularly cycling women in whom SES, body size, and reproductive variables have been documented. As a step towards better understanding the role of areolar diameter in reflecting estradiol-progesterone balance, this study aims to document the average mean bilateral lateral areolar diameter (AD) in a cohort of regularly menstruating, premenopausal women in whom ovulation was documented in one cycle. We also aim to describe relationships between AD and demographic, anthropometric, and reproductive/ovulation variables. Women were eligible if aged 19-35 years with about month-apart cycles and no exogenous hormone use in the last 3-months. Participants completed one cycle with a daily Menstrual Cycle Diary© (cycle length, CL) and first morning temperatures for Quantitative Basal Temperature© (QBT©) ovulation analysis (normal luteal phase length ≥10 days). Questionnaires gathered SES, ethnic, general health, and reproductive characteristics. Bilateral horizontal areolar diameters were measured by a woman researcher with the participant supine in a warm room. From February 2020 to September 2022 (during the SARS-CoV-2 pandemic), 73 women from Metro Vancouver, British Columbia participated. Women were of median (min-max) age 30 (19-35) years, BMI 24.5 (17.1-41.4) and most identified as White (61.6%) with a median of 16 years of education. Median CL was 29 days (n=65) and QBT data showed 39.3% were normally ovulatory, 34.4% had short luteal phases and 26.2% were anovulatory. Median within-woman bilateral AD was 3.85 (2.35-8.00) cm. Left AD exceeded right (L 3.8 [2.3,8.2]; R 3.7 [ 2.4,7.8]; P=.003). Larger AD (≥3.85cm) was associated with greater body size (BMI r=.534), weight and waist circumference. However, earlier age at menarche (P=.02) was also significantly associated. No other reproductive variables (cycle length, luteal phase length, parity, ever use of CHC) were related to AD before body size adjustments. This study is the first to document, and describe demographic, anthropomorphic and reproductive associations with, AD in community dwelling, regularly cycling, premenopausal women. Future steps will determine the most influential of the anthropometric variables; adjustment for these will facilitate assessments of associations with ovulation related characteristics. Presentation: Monday, July 14, 2025

fertility-awareness/effectiveness/comparative-effectiveness research-methods/measurement-and-statistics/instrument-development-and-validationmenstrual-cycle/cycle-biomarkers/basal-body-temperature Open Access

Accuracy of an Overnight Axillary-Temperature Sensor for Ovulation Detection: Validation in 194 Cycles

Shpaichler Y et al., 2025 Sensors

Several studies have evaluated the reliability of using temperature sensors placed in different locations on the body to identify the day of ovulation. However, such demonstrations are lacking for axillary temperature wearable devices. This study aimed to evaluate the accuracy with which an axillary temperature armband sensor (Tempdrop) identifies the day of ovulation and the fertile window, using the Clearblue Connected Ovulation Test System as the reference method. A total of 194 cycles were analyzed from 125 women that participated in the study between April 2023 and June 2024. The performance parameters were high: the sensitivity (96.8% (95% CI 95.6; 97.7)), specificity (99.1% (98.8; 99.4)), accuracy (98.6% (98.2; 98.9)), positive predictive value (96.8% (95.6; 97.7)) and negative predictive value (99.1% (98.8; 99.4)). Furthermore, the results revealed a remarkably clear and better-than-expected change in temperature around the time of ovulation. This axillary temperature wearable sensor is an effective alternative to urine ovulation tests for determining the timing of ovulation. Another advantage is that it provides a clear temperature curve that can be used to evaluate the quality of the luteal phase.