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.
PMID 527887 527887 DOI 10.1159/000299936 10.1159/000299936 Morishita et al. 1979, Morishita 1979
Cite this article
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.
Keywords
Adult, Body Temperature, Cervix Mucus/metabolism/physiology, Estradiol/blood, Female, Follicle Stimulating Hormone/blood, Humans, Luteinizing Hormone/blood, Ovulation, Ovulation Detection, Progesterone/blood, Progesterone, Estradiol, Luteinizing Hormone, Follicle Stimulating Hormone, Basal Body Temperature Method, Biology, Cervical Mucus--analysis, Cervix, Correlation Studies, Endocrine System, Estradiol, Estrogens, Examinations And Diagnoses, Family Planning, Family Planning, Behavioral Methods, Follicle Stimulating Hormone, Genitalia, Genitalia, Female, Gonadotropins, Gonadotropins, Pituitary, Hormones, Laboratory Examinations And Diagnoses, Laboratory Procedures, Luteinizing Hormone, Natural Family Planning, Ovulation Detection, Physiology, Progestational Hormones, Progesterone, Prospective Studies, Research Methodology, Statistical Studies, Studies, Urogenital System, Uterus
Nine healthy fertile women were studied during 29 menstrual cycles. A cervical mucus grading system, assessed by the patient and used in conjunction with basal body temperature, was correlated with plasma levels of luteinizing hormone (LH), oestradiol and plasma progesterone. The results show that a patient can be taught to predict the time of ovulation by observing the changes in the cervical mucus.
What is the normal range of cervical mucus patterns and number of days with high or moderate day-specific probability of pregnancy (if intercourse occurs on a specific day) based on cervical mucus secretion, in women without known subfertility, and how are these patterns related to parity and age? The mean days of peak type (estrogenic) mucus per cycle was 6.4, the mean number of potentially fertile days was 12.1; parous versus nulliparous, and younger nulliparous (<30 years) versus older nulliparous women had more days of peak type mucus, and more potentially fertile days in each cycle. The rise in estrogen prior to ovulation supports the secretion of increasing quantity and estrogenic quality of cervical mucus, and the subsequent rise in progesterone after ovulation causes an abrupt decrease in mucus secretion. Cervical mucus secretion on each day correlates highly with the probability of pregnancy if intercourse occurs on that day, and overall cervical mucus quality for the cycle correlates with cycle fecundability. No prior studies have described parity and age jointly in relation to cervical mucus patterns. STUDY DESIGN, SIZE, This study is a secondary data analysis, combining data from three cohorts of women: 'Creighton Model MultiCenter Fecundability Study' (CMFS: retrospective cohort, 1990-1996), 'Time to Pregnancy in Normal Fertility' (TTP: randomized trial, 2003-2006), and 'Creighton Model Effectiveness, Intentions, and Behaviors Assessment' (CEIBA: prospective cohort, 2009-2013). We evaluated cervical mucus patterns and estimated fertile window in 2488 ovulatory cycles of 528 women, followed for up to 1 year. PARTICIPANTS/MATERIALS, SETTING, Participants were US or Canadian women age 18-40 years, not pregnant, and without any known subfertility. Women were trained to use a standardized protocol (the Creighton Model) for daily vulvar observation, description, and recording of cervical mucus. The mucus peak day (the last day of estrogenic quality mucus) was used as the estimated day of ovulation. We conducted dichotomous stratified analyses for cervical mucus patterns by age, parity, race, recent oral contraceptive use (within 60 days), partial breast feeding, alcohol, and smoking. Focusing on the clinical characteristics most correlated to cervical mucus patterns, linear mixed models were used to assess continuous cervical mucus parameters and generalized linear models using Poisson regression with robust variance were used to assess dichotomous outcomes, stratifying by women's parity and age, while adjusting for recent oral contraceptive use and breast feeding. MAIN The majority of women were <30 years of age (75.4%) (median 27; IQR 24-29), non-Hispanic white (88.1%), with high socioeconomic indicators, and nulliparous (70.8%). The mean (SD) days of estrogenic (peak type) mucus per cycle (a conservative indicator of the fertile window) was 6.4 (4.2) days (median 6; IQR 4-8). The mean (SD) number of any potentially fertile days (a broader clinical indicator of the fertile window) was 12.1 (5.4) days (median 11; IQR 9-14). Taking into account recent oral contraceptive use and breastfeeding, nulliparous women age ≥30 years compared to nulliparous women age <30 years had fewer mean days of peak type mucus per cycle (5.3 versus 6.4 days, P = 0.02), and fewer potentially fertile days (11.8 versus 13.9 days, P < 0.01). Compared to nulliparous women age <30 years, the likelihood of cycles with peak type mucus ≤2 days, potentially fertile days ≤9, and cervical mucus cycle score (for estrogenic quality of mucus) ≤5.0 were significantly higher among nulliparous women age ≥30 years, 1.90 (95% confidence interval (CI) 1.18, 3.06); 1.46 (95% CI 1.12, 1.91); and 1.45 (95% CI 1.03, 2.05), respectively. Between parous women, there was little difference in mucus parameters by age. Thresholds set a priori for within-woman variability of cervical mucus parameters by cycle were examined as follows: most minus fewest days of peak type mucus >3 days (exceeded by 72% of women), most minus fewest days of non-peak type mucus >4 days (exceeded by 54% of women), greatest minus least cervical mucus cycle score >4.0 (exceeded by 73% of women), and most minus fewest potentially fertile days >8 days (found in 50% of women). Race did not have any association with cervical mucus parameters. Recent oral contraceptive use was associated with reduced cervical mucus cycle score and partial breast feeding was associated with a higher number of days of mucus (both peak type and non-peak type), consistent with prior research. Among the women for whom data were available (CEIBA and TTP), alcohol and tobacco use had minimal impact on cervical mucus parameters. LIMITATIONS, We did not have data on some factors that may impact ovulation, hormone levels, and mucus secretion, such as physical activity and body mass index. We cannot exclude the possibility that some women had unknown subfertility or undiagnosed gynecologic disorders. Only 27 women were age 35 or older. Our study participants were geographically dispersed but relatively homogeneous with regard to race, ethnicity, income, and educational level, which may limit the generalizability of the findings. Patterns of cervical mucus secretion observed by women are an indicator of fecundity and the fertile window that are consistent with the known associations of age and parity with fecundity. The number of potentially fertile days (12 days) is likely greater than commonly assumed, while the number of days of highly estrogenic mucus (and higher probability of pregnancy) correlates with prior identifications of the fertile window (6 days). There may be substantial variability in fecundability between cycles for the same woman. Future work can use cervical mucus secretion as an indicator of fecundity and should investigate the distribution of similar cycle parameters in women with various reproductive or gynecologic pathologies. STUDY FUNDING/COMPETING INTEREST(S): Funding for the three cohorts analyzed was provided by the Robert Wood Johnson Foundation (CMFS), the Eunice Kennedy Shriver National Institute of Child Health and Human Development (TTP), and the Office of Family Planning, Office of Population Affairs, Health and Human Services (CEIBA). The authors declare that they have no conflict of interest. N/A.
In order to evaluate the relationship between the urinary luteinizing hormone (LH) surge as detected by the OvuSTICK (Monoclonal Antibodies, Inc., Mountain View, CA) method and daily cervical mucus parameters, ten spontaneously ovulating women undergoing infertility evaluation were followed during their cycles with twice daily urinary LH testing as well as daily ultrasound, mucus evaluation, and hormonal assays of serum LH, progesterone (P), and estradiol (E2). Maximal cervical mucus scores, as determined using a modified Insler score, were noted to coincide consistently with the urinary LH surge as detected by twice daily testing and to precede ultrasound evidence of ovulation by 0 to 24 hours. Mucus scores rapidly declined in the 24-hour period following the urinary LH surge. Detection of the urinary LH surge may therefore help identify that period of time during which cervical mucus parameters are optimal and therefore facilitate the timing of artificial insemination, intercourse, or postcoital testing.
Natural methods of family planning make use of the naturally occurring signs and symptoms of the fertile and infertile phases of the menstrual cycle. Recognizable signs and symptoms occur cyclically, and women can be taught to recognize them. Changes take place in basal body temperature, cervical mucus, and the cervix uteri. Basal body temperature rises about .2 degrees C (.4 degrees F) immediately after ovulation when the blood levels of progesterone increase. Following menstruation, cervical mucus is composed of cense cellular matter that forms an impenetrable barrier (typeG). As the cycle progresses under the influence of increasing estrogen, there is a predominance of characteristically lumpy opaque mucus (type L). A few days before ovulation, the characteristically thin slippery crystal clear stretchy mucus is produced (type S). Fertile mucus is composed of a combination of L-type and S-type mucus. Estrogen casuses changes to take place in the muscle and connective tissue of the cervix. As estrogen levels rise during the pre-ovulatory phase, the cervix softens and the cervical os opens. A woman can be aware of these changes by gently palpating the cervix with her finger tip. These signs and symptoms which reflect accurately the rise and fall of the hormones estrogen and progesterone are the basis of fertility awareness on which natural methods of family planning are based. In addition to knowing when ovulation takes place, it is also necessary to know the length of time the ovum can be fertilized after ovulation and the life span of the sperm in the female genital tract before ovulation. In fertile mucus, sperm will live an average of 3 days, but it must be understood that it is possible for sperm to survive for 5 days if conditions are right. To make allowances for sperm survuval, the fertile phase starts when follicular development begins and estrogen levels start to rise. The life span of the ovum is less than 24 hours. Natural family planning methods--including the temperature method, the ovulation method (Billings), the calandar method (rhythm), and the sympto-thermal method are explained.