Morishita, H., Hashimoto, T., Mitani, H., Tanaka, T., Higuchi, K., & Ozasa, T. (1979). Cervical mucus and prediction of the time of ovulation. Gynecologic and Obstetric Investigation, 10(4), 157-162. https://doi.org/10.1159/000299936
Morishita H, Hashimoto T, Mitani H, Tanaka T, Higuchi K, Ozasa T. Cervical mucus and prediction of the time of ovulation. Gynecol Obstet Invest. 1979;10(4):157-162. doi:10.1159/000299936
Morishita, H., et al. "Cervical mucus and prediction of the time of ovulation." Gynecologic and Obstetric Investigation, vol. 10, no. 4, 1979, pp. 157-162.
Clear mucus onset came about 2 days before the LH peak on average
Clear cervical mucus began increasing an average of about 2 days before the luteinizing hormone (LH) peak in 12 women. This 1979 study followed women with normal ovulation for 17 cycles. Mucus and blood were sampled daily around midcycle. The authors conclude the first day of increasing clear mucus can predict the time of ovulation in these women.
Study at a glance, cohort study of 12 women with normal ovulation: Clear mucus onset came about 2 days before the LH peak. Source: Morishita H et al., 1979, PMID 527887.
Key Findings
The study followed 12 women with normal ovulation, aged 22 to 32 years (mean 27 years), across 17 menstrual cycles.
Increasing quantities of clear cervical mucus (IQCCM) began a mean of 1.4 ± 0.2 (SE) days before the estradiol peak, ranging from 1 to 2 days.
The LH peak occurred a mean of 1.8 ± 0.2 (SE) days after IQCCM began, with a range from 1 to 3 days.
In 8 of the 12 women, IQCCM began 2 days before the LH peak.
Basal body temperature was biphasic in all cycles, and its significant rise came 2 days after the LH peak.
Interpretation
This cohort study followed 12 women with normal ovulation across 17 cycles. Researchers sampled cervical mucus and blood each day around midcycle. They aspirated mucus from the cervical canal with a syringe. Onset was the first day with 0.1 ml or more of clear mucus. They also tracked LH, FSH, estradiol, progesterone, and basal body temperature. Clear mucus onset tracked closely with the estradiol and LH peaks, coming about 1 to 2 days before the LH surge. The authors note that ovulation occurs about 16 hours after the LH peak, based on earlier work. The findings support larger studies of mucus observation as a way to predict ovulation.
RRM Context
Fertility awareness-based methods (FABMs) track cervical mucus as a key cycle sign. This study ties the mucus change to the hormone shifts of ovulation. Restorative reproductive medicine treats cycle signs as useful clues about how the body works.
Our editorial summary of this paper, not the article's abstract.
Abstract
12 normal ovulatory women were studied during 17 menstrual cycles. The first day on which the women had increasing quantities of 0.1 ml or more clear cervical mucus (IQCCM) was closely related to the time of ovulation as monitored by basal body temperature and radioimmunoassay of serum-luteinizing hormone, follicle-stimulating hormone, estradiol, and progesterone. The results show that the time of ovulation can be predicted clinically without specialized tests by observing the day of onset of IQCCM.
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