Determining Ovulation: Egg White Cervical Mucus vs. Basal Body Temperature

The day of ovulation is determined by the rise in basal body temperature rather than the presence of egg white cervical mucus. The basal body temperature typically increases after ovulation due to the rise in progesterone levels. Therefore, ovulation occurs on the day before the temperature increase?

Hello doctor, I have been measuring my basal body temperature for a few months.
From last month to this month, I measured it at specific times.
Since the month before last, my cycle has stabilized at 29 days, whereas previously it varied between 28, 29, 30, 31, and 32 days.
My menstrual period is quite regular; usually, if it starts on a certain day last month, it will start on the same day next month.
However, I stopped measuring my temperature about a week before my period.
I started measuring on the first day of my period.
After observing for two months, I noticed that on days 13 and 14 after my period, I had cervical mucus resembling egg whites.
This month, my temperatures were as follows: 11/30 36.38, first day of period 12/1 35.17, 12/2 36.08, 12/4 36.08, 12/5 36.17, 12/6 36.68, end of period 12/7 36.18, 12/8 36.18, 12/9 36.08, 12/10 36.14, 12/11 36.18, 12/12 36.18, 12/13 36.39.

I would like to ask, is the actual ovulation day the same as the day of intercourse? Or is it sufficient to have egg white cervical mucus? Regarding basal body temperature, is the day of temperature drop the ovulation day, or is it the day after when the temperature rises? I observed egg white cervical mucus on 12/10, and the temperature dropped on 12/9.
Does this mean that intercourse on 12/10 and 12/11 would be effective? I'm confused about whether the day of temperature drop and the following day is the fertile window, or if it is the day of egg white cervical mucus and the following day that is the fertile window.

Fang, 30~39 year old female. Ask Date: 2015/12/13

Dr. Lü Lizheng reply Obstetrics and Gynecology

1.
A rise in basal body temperature indicates that ovulation has already occurred.
The day before is typically the ovulation period.

2.
The day when the egg white cervical mucus is most abundant and viscous may indicate the ovulation period.

Respectfully, Dr.
Li-Cheng Lu, Taoyuan Hospital.

Reply Date: 2015/12/13

More Info

Determining ovulation can be a complex process, and it often involves tracking multiple indicators, including basal body temperature (BBT) and cervical mucus characteristics. Both of these methods can provide valuable insights into your ovulation cycle, but they do so in different ways.

Basal Body Temperature (BBT): BBT is your body's temperature at rest, and it typically rises slightly after ovulation due to increased progesterone levels. This rise usually occurs about 24 to 48 hours after ovulation. To effectively use BBT for ovulation tracking, it is essential to take your temperature at the same time every morning before getting out of bed. A sustained increase in temperature for at least three days indicates that ovulation has likely occurred. In your case, you noted a temperature drop on December 9 and a rise on December 10, which suggests that ovulation likely occurred on December 10 or possibly December 9.

Cervical Mucus: The consistency and appearance of cervical mucus change throughout your menstrual cycle. Around ovulation, cervical mucus often becomes clear, stretchy, and resembles raw egg whites—this is referred to as "egg white cervical mucus" (EWCM). The presence of EWCM is a strong indicator that you are in your fertile window, which typically lasts for a few days leading up to and including ovulation. In your observation, you noted the presence of egg white cervical mucus around December 10, which aligns with the fertile window.

Timing of Intercourse: The timing of intercourse in relation to ovulation is crucial for conception. Sperm can live inside the female reproductive tract for up to five days, while an egg is viable for about 12 to 24 hours after ovulation. Therefore, the best time to have intercourse is during the days leading up to ovulation and on the day of ovulation itself. Given your observations, having intercourse on December 10 and 11 would be ideal, as this coincides with the presence of EWCM and the rise in BBT.

Conclusion: Based on your data, it appears that ovulation likely occurred on December 10, with the presence of egg white cervical mucus indicating peak fertility. The drop in BBT on December 9 followed by a rise on December 10 further supports this. Therefore, engaging in intercourse on December 10 and 11 would be considered optimal for conception.

In summary, both BBT and cervical mucus are valuable tools for determining ovulation. While BBT indicates that ovulation has already occurred, cervical mucus can help identify the fertile window leading up to ovulation. For the best chances of conception, it is advisable to have intercourse during this fertile window, particularly on the day of ovulation and the days leading up to it. If you continue to track these indicators over several cycles, you may gain a clearer understanding of your ovulation patterns, which can be beneficial for family planning. If you have further questions or concerns about your menstrual cycle or fertility, consulting with a healthcare provider or a fertility specialist can provide personalized guidance and support.

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