Evans-Hoeker, E., Pritchard, D. A., Long, D. L., Herring, A. H., Steiner, A. Z., & Stanford, J. B. (2013). Cervical mucus monitoring prevalence and associated fecundability in women trying to conceive. Fertility and Sterility, 100(4), 1033-1038.e1. https://doi.org/10.1016/j.fertnstert.2013.06.002
Evans-Hoeker E, Pritchard DA, Long DL, Herring AH, Steiner AZ, Stanford JB. Cervical mucus monitoring prevalence and associated fecundability in women trying to conceive. Fertil Steril. 2013;100(4):1033-1038.e1. doi:10.1016/j.fertnstert.2013.06.002
Evans-Hoeker, E., et al. "Cervical mucus monitoring prevalence and associated fecundability in women trying to conceive." Fertility and Sterility, vol. 100, no. 4, 2013, pp. 1033-1038.e1.
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Consistent cervical mucus monitoring associated with more pregnancies
A cohort study of 331 women aged 30 to 44 trying to conceive found that consistent cervical mucus monitoring was associated with higher chances of pregnancy each cycle. Only 6 out of 100 women monitored consistently in their first cycle. Adjusting for intercourse frequency left the association in place.
Key Findings
In the first study cycle, 20 of 331 women (6%) monitored consistently (more than 66% of pertinent days), 60 (18%) inconsistently, 73 (22%) infrequently, and 178 (54%) not at all.
Consistently monitored cycles were associated with more conceptions than unmonitored cycles: fecundability ratio 2.29 (95% CI 1.22 to 4.32), adjusted for age, race, previous pregnancy, BMI and urinary LH monitoring.
Adding intercourse frequency in the fertile window to the adjustment gave a fecundability ratio of 2.32 (95% CI 1.23 to 4.40).
Infrequent monitoring gave 1.10 (95% CI 0.71 to 1.74) and inconsistent monitoring 1.36 (95% CI 0.81 to 2.30). Fecundability rose with consistency (P = .01).
Across all cycles, women monitored mucus in 42% of cycles. Type 3 mucus was reported most often (40%) and type 4 least often (15%).
Interpretation
The cohort design shows an association between monitoring and pregnancy. The authors name hidden confounding as a possible explanation, and alcohol and caffeine use were not adjusted for. Participants were highly educated, enrolled early in their attempts to conceive, and the cohort lacked women of younger reproductive ages. The fertile window was estimated from cycle length. Only 20 women monitored consistently in their first cycle. The authors call for a randomized trial.
RRM Context
Cervical mucus observation is a core biomarker in fertility awareness-based methods, which chart the cycle to locate the fertile window. The authors cite earlier work linking the mucus type seen on the day of intercourse to the chance of conception. Charting gives couples day-by-day information from the body's own cycle.
Our editorial summary of this paper, not the article's abstract.
Abstract
Objective
To assess the use of cervical mucus monitoring (CMM) in women trying to conceive and determine whether monitoring is associated with increased cycle-specific probability of conception (fecundability).
Design
Time-to-pregnancy cohort study.
Setting
Population-based cohort.
Patients
Three hundred thirty-one women trying to conceive, ages 30 to 44 years, without known infertility.
Interventions
None.
Main Outcome Measures
CMM prevalence and fecundability.
Results
During the first cycle of the study, CMM was performed consistently (checked on >66% of pertinent cycle days) by 20 women (6%), inconsistently (34% to 66% of days) by 60 women (18%), infrequently (≤33% of days) by 73 women (22%), and not performed by 178 women (54%). Cycles in which CMM was consistently performed were statistically significantly more likely to result in conception after adjusting for age, race, previous pregnancy, body mass index, intercourse frequency, and urinary luteinizing hormone (LH) monitoring. Fecundability also increased with increasing consistency of CMM.
Conclusions
Among women trying to conceive, CMM is uncommon, but our study suggests that CMM-a free, self-directed method to determine the fertile window-is associated with increased fecundability independent of intercourse frequency or use of urinary LH monitoring.
