From the Guidelines
Clear cervical mucus is a sign that ovulation is approaching, but it doesn't definitively indicate that ovulation has occurred. According to the recommendations of the CDC and the U.S. Office of Population Affairs, as outlined in the study 1, providers should educate clients about peak days and signs of fertility, including the 6-day interval ending on the day of ovulation characterized by slippery, stretchy cervical mucus. This type of mucus is typically present 1-5 days before ovulation and is a result of rising estrogen levels. Some key points to consider when maximizing fertility include:
- Educating the client about peak days and signs of fertility
- Advising women with regular menstrual cycles to have vaginal intercourse every 1–2 days beginning soon after the menstrual period ends
- Discussing methods or devices designed to determine or predict the time of ovulation
- Noting that fertility rates are lower among women who are very thin or obese, and those who consume high levels of caffeine. It's essential to use clear cervical mucus as one indicator among several when tracking fertility, such as basal body temperature charting, ovulation predictor kits, or fertility monitoring devices, as the presence of clear mucus alone cannot confirm that an egg has been released. The pattern of cervical mucus changes throughout the menstrual cycle due to hormonal fluctuations, starting dry after menstruation, becoming sticky, then creamy, then clear and slippery near ovulation, before returning to thicker or drier consistency after ovulation has occurred.
From the Research
Clear Cervical Mucus and Ovulation
- Clear cervical mucus is often associated with ovulation, but its presence alone does not definitively indicate ovulation 2, 3.
- The peak mucus symptom is closely correlated with ovulation, and observed changes in cervical mucus patterns can be used to define the probable fertile period 2.
- Studies have shown that the peak day of cervical mucus is a reliable indicator of ovulation, with 97.8% of peak days falling within +/- 4 days of the estimated day of ovulation 4.
- Women's daily tracking of cervical mucus is a low-cost alternative for identifying the estimated day of ovulation, with a high agreement between cervical mucus peak day and the day of ovulation 5.
Characteristics of Cervical Mucus
- Cervical mucus is an aqueous or gel mixture of fluids, ions, and compounds, and cells, primarily produced by the endocervical epithelium 3.
- The amount of mucus secreted varies with menstrual phase, and its composition changes under hormonal influence 3.
- Dried mucus has a fern appearance due to NaCl crystals at ovulation, and its soluble proteins, amino acids, and simple sugars show wide fluctuation, influencing sperm penetration and nutrition 3.
Comparison with Other Indicators of Ovulation
- Urine LH monitors are becoming more widely available and less expensive, giving women the potential to assess the ovulatory status of their cycle in real time 6.
- Cervical mucus observation is an effective and cost-efficient method, but requires some teaching to increase the confidence of users 6.
- Basal body temperature (BBT) is at best a retrospective marker of ovulation and functions best in conjunction with other signs of ovulation 2, 6.