Elsevier

Obstetrics & Gynecology

Volume 101, Issue 6, June 2003, Pages 1285-1293
Obstetrics & Gynecology

Original research
Vulvar mucus observations and the probability of pregnancy☆

https://doi.org/10.1016/S0029-7844(03)00358-2Get rights and content

Abstract

Objective

To assess the day-specific and cycle-specific probabilities of conception leading to clinical pregnancy, in relation to the timing of intercourse and vulvar mucus observations.

Methods

This was a retrospective cohort study of women beginning use of the Creighton Model Fertility Care System in Missouri, Nebraska, Kansas, and California. Data were abstracted from Creighton Model Fertility Care System records, including women’s daily standardized vulvar observations of cervical mucus discharge, days of intercourse, and clinically evident pregnancy (conception). Established statistical models were used to estimate day-specific probabilities of conception.

Results

Data were analyzed from 1681 cycles with 81 conceptions from 309 normally fertile couples (initially seeking to avoid pregnancy) and from 373 cycles with 30 conceptions from 117 subfertile couples (who were initially trying to achieve pregnancy). The highest probability of pregnancy occurred on the peak day of vulvar mucus observation (.38 for normally fertile couples and .14 for subfertile couples). The probability of pregnancy was greater than .05 for normally fertile couples from 3 days before to 2 days after the peak, and for subfertile couples from 1 day before to 1 day after the peak. The cycle-specific probability of conception correlated with the quality of mucus discharge in normally fertile couples but not in subfertile couples.

Conclusion

Standardized vulvar observations of vaginal mucus discharge identify the days with the greatest likelihood of conception from intercourse in normal fertility and subfertility and provide an indicator of the overall potential for conception in a given menstrual cycle in normal fertility.

Section snippets

Materials and methods

Ours was a retrospective cohort study using data extracted from existing standard teacher and user records of the Creighton Model Fertility Care System. All new users of the Creighton Model Fertility Care System from six different Creighton Model Fertility Care System centers in four different cities (in Missouri, Nebraska, Kansas, and California) for the years 1990–1996 were considered potentially eligible for this study. A detailed description of these new users has been published previously.

Results

The demographic characteristics and reproductive history of the initially screened sample have been reported in detail elsewhere.21 (One Creighton Model Fertility Care System center that initially contributed screening data withdrew from the study before contributing final data.) Of 1278 new users of the Creighton Model Fertility Care System at the six centers, 184 were excluded because they were breast-feeding or pregnant, 72 because they were younger than 18 years or older than 39, and six

Discussion

Our results confirm that the clinical observation of vaginal discharge at the vulva can be used to prospectively identify the fertile days of the menstrual cycle (ie, the days when intercourse is most likely to result in pregnan-cy).11, 25, 26 Vulvar observations of these changes are easily learned and interpreted by women of all socioeconomic backgrounds.27

The maximum probability of conception in our study in couples of apparently normal fertility (from intercourse on the peak day) is .38,

Acknowledgements

The authors thank Becky Crockett, Mary Bishop Stone, and Julie Fryer for research assistance. Thomas W. Hilgers, MD, and James Trussell, PhD, served as consultants to this study.

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    ☆

    Primary funding for this study was provided by the Robert Wood Johnson Foundation through the Generalist Physician Faculty Scholars Program (JBS). Additional funding was provided by the Health Studies Fund, Department of Family and Preventive Medicine, University of Utah.

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    Copyright © 2003 The American College of Obstetricians and Gynecologists. Published by Elsevier Inc. All rights reserved.