Self identification of the clinical fertile window and the ovulation period

Cervical mucus resulting from estrogen changes, observed by self-inspection, is 88% sensitive in identifying a 2-day OW, as confirmed by daily ultrasound.

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Rene Ecochard, M.D., Ph.D., Olivia Duterque, M.D., Rene Leiva, M.D., Thomas Bouchard, M.D., Pilar Vigil, M.D.

Volume 103, Issue 5, Pages 1319-1325



To assess the sensitivity and specificity of the self-identified fertile window.


Observational study.


Not applicable.


A total of 107 women.


Women recorded cervical mucus observation and basal body temperature daily while undergoing daily ovarian ultrasound.

Main Outcome Measure(s):

The biological fertile window, defined as the 6 days up to and including the day of ovulation; and the 2-day ovulation window, defined as the day before and the day of ovulation.


The self-identification of the biological fertile window by the observation of any type of cervical mucus provides 100% sensitivity but poor specificity, yielding a clinical fertile window of 11 days. However, the identification of the biological fertile window by peak mucus (defined as clear, slippery, or stretchy mucus related to estrogen) yielded 96% sensitivity and improved specificity. The appearance of the peak mucus preceded the biological fertile window in less than 10% of the cycles. Likewise, this type of mucus identified the ovulation window with 88% sensitivity.


These results suggest that, when perceived accurately, more accurate clinical self-detection of the fertile window can be obtained by identification of peak mucus. This may improve efforts to focus intercourse in the fertile phase for couples with fertility concerns.

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Fertility and Sterility

Editorial Office, American Society for Reproductive Medicine

Fertility and Sterility® is an international journal for obstetricians, gynecologists, reproductive endocrinologists, urologists, basic scientists and others who treat and investigate problems of infertility and human reproductive disorders.