Self-identification of the clinical fertile window and the ovulation period

Fertil Steril. 2015 May;103(5):1319-25.e3. doi: 10.1016/j.fertnstert.2015.01.031. Epub 2015 Feb 24.


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

Design: Observational study.

Setting: Not applicable.

Patient(s): A total of 107 women.

Intervention(s): 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.

Result(s): 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.

Conclusion(s): 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.

Keywords: Fertile window; cervical mucus; fertility awareness methods; menstrual cycle; ovulation.

Publication types

  • Multicenter Study
  • Observational Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Body Temperature Regulation
  • Cervix Mucus / metabolism
  • Europe
  • Female
  • Fertile Period*
  • Fertility*
  • Humans
  • Ovary / diagnostic imaging
  • Ovary / physiology*
  • Ovulation Detection / methods*
  • Ovulation*
  • Predictive Value of Tests
  • Self Care*
  • Time Factors
  • Ultrasonography