Tools to help predict ovulation are a valuable resource for couples who wish to conceive a child. The normal conception rate for fertile couples who are attempting to achieve pregnancy is 15–25% per cycle.[4,5] Therefore, most couples will achieve pregnancy within one year. However, 1 in 10 couples of reproductive age encounter some level of infertility, and these couples often seek methods to help predict the window of maximum fertility. A number of home testing devices can help patients more accurately predict ovulation ( Table 1 ).[6,7,8,9,10] If a couple does not conceive after one year of unprotected intercourse around the time of maximum fertility, the pair should be advised to seek medical care for infertility evaluation. However, if the woman is 35 years or older, has a complicated gynecological history (e.g., uterine disease, tubal disease, endometriosis, oligomenorrhea, amenorrhea), or has a partner with known subfertility, the couple should seek medical advice sooner. In the meantime, home fertility monitoring can help guide the couple as they attempt to conceive.
Ovulation-prediction devices monitor natural changes that occur in a woman's body during the menstrual cycle. During the follicular phase of the menstrual cycle, there is a gradual rise in follicle-stimulating hormone (FSH), luteinizing hormone (LH), and estrogen.[5,11,12] Once estrogen levels reach a critical concentration and duration, the pituitary gland releases an LH surge, which results in the final maturation of the follicle, follicle release, and corpus luteum formation. After ovulation, estrogen and progesterone levels continue to rise in order to promote a thick, fertile endometrium for optimal implantation.[11,12] Around the time of ovulation, a woman experiences variations in her basal body temperature (BBT) and changes in the consistency of her oral and vaginal secretions. She might also notice increased libido and abdominal or lower-back discomfort. FSH and LH increase in the bloodstream and the urine.[4,5,11,13] After ovulation, the ovum is viable for only about 12–24 hours, while sperm survive for up to 72 hours in the female reproductive tract. Therefore, the window for maximum fertility extends from two days before to 24 hours after ovulation. Wilcox et al. found the highest conception rate when couples had intercourse within six days of ovulation, with the highest probability (estimated conception rate ± S.E.) occurring two days before (0.27 ± 0.7), one day before (0.31 ± 0.6), and on the day of ovulation (0.33 ± 0.9). Therefore, to identify the time of maximum fertility, it is important to accurately predict the time of ovulation.[4,5,13,14]
Reproductive endocrinologists predict ovulation by drawing daily blood samples in midcycle to monitor changes in plasma FSH, LH, and estradiol and by conducting daily vaginal ultrasound monitoring to visualize follicular growth and collapse. Evaluating serum progesterone concentrations during the luteal phase may also confirm ovulation.[4,12] These techniques, although very accurate, involve invasive testing and daily physician office visits. They are often used for the management of infertility, especially when couples pursue artificial reproductive technologies.[4,5,15] Several more affordable, noninvasive testing options are sold in pharmacies that can help patients monitor fertility at home.
One simple and useful method for predicting fertility is BBT monitoring.[4,5,16] The female body temperature measured orally typically ranges from 96 to 98 °F before ovulation. Just before ovulation there is a slight dip in temperature, followed by an increase of 0.5 to 1.6 °F in the basal reading because of increased progesterone levels in the body. Therefore, after ovulation the female body temperature taken orally is typically 97 to 99 °F.[16,17,18] The temperature remains high throughout the remainder of the cycle. By carefully monitoring, documenting, and charting temperature readings, a woman can track small changes that might signal that ovulation has occurred.[16,17,18]
To facilitate monitoring, special BBT thermometers are available. These thermometers measure temperatures from 96 to 101 °F in 0.1 °F increments. BBT thermometers on the market range from simple, mercury-free glass thermometers to digital models with memory. The digital models often report temperature to within 0.01 °F. Charts are often included in the packaging so that women can graph the results; alternatively, blank charts can be downloaded from the Internet. Computer software programs are also available for tracking.[19,20]
BBT monitoring should begin on the first day of a woman's menstrual cycle. Women must take their temperature after at least three to four hours of sleep.[5,17] They should take their temperature as soon as they wake up, while they are still lying in bed. It is important that they do not eat, drink, or exercise before the reading. Temperatures should be measured for five minutes, and then the scale should be carefully read and the results recorded. Digital models usually take less time to detect a stable reading and beep when ready to be read. Temperatures can be measured orally or vaginally, but the method of measurement should be consistent throughout the month. At the time of ovulation, BBT will rise 0.4–0.8 °F; this temperature change may be gradual or rapid.[5,17,18]
BBT monitoring is most useful to analyze menstrual cycle trends from month to month so that a woman can become more aware of her ovulation patterns, enabling the couple to time intercourse during the projected window of fertility in future months. Patients should be aware that BBT indicates that ovulation has already occurred. Once the trend in BBT is noted, the 24-hour window for fertilization has already passed for the current month. To predict the time of ovulation, other devices are necessary.[4,16]
Because BBT monitoring is most effective when the temperature is measured at approximately the same time each day after a good night's sleep, it might not be a good alternative for a woman who has an unpredictable schedule, disrupted sleep, or inconsistent sleep patterns. BBT readings can be affected by factors such as illness, infection, anxiety, stress, fatigue, jet lag, nightmares, insomnia, smoking, exercise, and electric blanket use.[5,16]
Several ovulation-prediction devices monitor changes in urinary LH concentrations. The surge in LH that triggers ovulation is detectable in the urine within 8–12 hours; ovulation should follow within 12–24 hours. Home devices for testing urinary LH contain monoclonal antibodies or a mixture of monoclonal and polyclonal antibodies that bind LH in the urine. During the test, if LH is present in the urine sample it is "sandwiched" between two antibodies. An enzyme-linked immunosorbent assay then detects the LH–antibody complex, causing a color change that the patient can view and interpret.[21,22] The intensity of the color change increases with higher concentrations of LH. The color for a positive result varies among products but is usually blue, blue-green, or pink.[16,21]
All products contain a control window that must activate after the urine sample is applied to show that the testing device is working correctly and the test result is valid. This control window may display a change in color or a line or symbol. Most products also have a window that displays the test results in the same manner as the control data.[13,21] A positive result may be difficult for the patient to interpret. For instance, with some test devices, the patient must watch for a peak change in color, indicating the highest concentration of LH. To simplify interpretation, newer products display an unambiguous symbol (such as a "smiley face") when the LH complex is detected.
Some clinicians define the LH surge as beginning when detectable LH reaches a concentration of 35–60 mIU/mL.[21,24] However, others define the surge as starting when the serum LH level reaches 1.5 times the mean preovulatory level observed during the follicular phase.[21,25] Most home urinary LH kits can detect LH concentrations at or above 20–40 mIU/mL, and when the devices are used as directed the results generally agree with those of more invasive laboratory tests used to predict ovulation.[15,21,26]
Studies have been conducted to evaluate the value of urinary LH kits for predicting ovulation in both fertile and infertile women.[21,26] In infertile women, ovulation was accurately predicted within 48 hours after the peak measured urinary LH level in 90–100% of cases; among fertile women, the predictive value ranged from 92% to 97%. However, some test devices are more sensitive than others. In one study, the ClearPlan Easy Ovulation Test Pack (Inverness Medical) was found to have the best sensitivity for detecting urinary LH—concentrations as low as 22 mIU/mL were detected. Other devices were comparable with good sensitivity, except Answer Quick (Carter–Wallace) and Simple One Step Ovulation Test (Carter–Wallace), which showed poor LH sensitivity.[22,27]
Patients may dislike collecting and handling urine samples, so some manufacturers have developed onestep testing strips that can be held in the urine stream.
Patients should be instructed to perform all urine tests first thing in the morning with the first urination of the day, when LH is most concentrated in the urine. It is very important that the patient read and follow the product-specific instructions for testing. If the test cannot be performed at the time of the day's first urination, then the urine sample can be refrigerated and tested later in the day; the sample should be returned to room temperature before testing.
The optimal time to begin daily urine testing varies from patient to patient, depending on the length of her menstrual cycle. For instance, if a woman has a 21-day cycle she should begin testing on day 6, but if she has a 30-day cycle she should delay testing until day 13. A table indicating when to initiate testing is included in the kit. Once started, testing should be continued for five to seven days. If a woman has an irregular menstrual cycle, she should continue testing for at least nine consecutive days until she detects an LH surge or begins her menstrual period. Failure to detect a surge between cycles might indicate that the surge was missed or that the patient had an anovulatory cycle.[13,22] An irregular menstrual cycle that necessitates an expanded testing window increases the cost of monitoring significantly.
Several health conditions related to infertility, and the drugs used to treat them, can interfere with the accuracy of urinary LH test results. This is an important counseling point.[13,22] Health conditions include endometriosis, polycystic ovarian syndrome, premature ovarian failure, perimenopause, menopause, and hyperthyroidism;[13,22] others include renal failure, gonadotropin-producing neoplasia, and pregnancy. Medications include menotropins, danazol, clomiphene, human chorionic gonadotropin (HCG), hormone supplementation, and steroids.
The Clear-blue Easy Fertility Monitor (CBEFM) (formerly known as the ClearPlan Easy Fertility Monitor, Inverness Medical) tests for two hormones in the urine, LH and estrone-3-glucuronide (E3G), which is the dominant metabolite of estradiol. Studies have found that urinary E3G concentrations are a good marker of the fertility window, while LH levels are the best predictors of imminent ovulation. Therefore, evaluating these two hormones together may provide more data on fertility status than either alone.[8,22] The CBEFM requires the patient to monitor her urine daily for 20 consecutive days in one month in order to collect baseline data on hormone levels before fertility testing begins. After this, the patient tests her urine once daily for 10–20 days per month. The monitor stores data and compares readings from day to day. The results are displayed on an easy-to-read screen that indicates low, high, or peak fertility on a bar graph. An egg symbol appears in the testing window on days of maximum fertility.[22,28]
Behre and colleagues found very good results with the CBEFM. The device never indicated peak fertility before ovulation occurred, and 63.5% of patients had up to seven days of warning before ovulation occurred; 91.1% of patients ovulated during the two-day window of maximum fertility indicated by the device; and 97.0% ovulated either during the two-day window or during the one day of high fertility that was indicated after the peak.
The CBEFM is an expensive initial investment compared with urinary LH test strips. In addition to the monitor, test strips must be purchased separately. However, the device is easy to use, results are very clear, and the patient receives more information concerning the fertility window than with other urine-testing methods.
During a woman's menstrual cycle, as estrogen levels increase in the body there is a corresponding increase in the amount of sodium chloride in mucus secretions (saliva and cervical–vaginal mucus), which results in crystallization or "ferning" of mucus when it is dried.[10,29] Therefore, one method that has been used to monitor fertility is visual inspection of saliva throughout the month. When a saliva sample is placed on a glass microscope slide and dried, a characteristic pattern of crystals may be seen. During the fertile period, the pattern changes from small dots to small ferns to large ferns, indicating low, intermediate, and high fertility, respectively.
Several compact, portable, and inexpensive microscopes are available for home monitoring of saliva. Several come in containers shaped and sized like lipstick cases. According to the manufacturers' websites, when used as directed these devices can provide 24–72 hours of advance notification of ovulation. However, for best results the patient should collect a "passive saliva" sample first thing in the morning, before she eats, drinks, or brushes her teeth. The sample should be evenly distributed across the slide. Air bubbles or excess saliva can alter the results. After the sample has air dried, it is visually inspected under the microscope, and the pattern is compared with reference patterns. Pregnancy, perimenopause, menopause, hormone imbalance, hormone replacement therapy, and hormonal contraception can interfere with the results.
Studies that have assessed home saliva microscopy for fertility monitoring have yielded conflicting results. One small study (n = 12) found a high correlation between saliva microscopy results and those of home urinary LH monitoring (r = 0.98, p < 0.001). However, the subjects found it very difficult to define the beginning and end of the fertility window. The subjects were not blinded to their urinary LH results, so this could have influenced saliva-ferning interpretation. Also, the subjects were fertility-planning teachers, which may have decreased the generalizability of the findings. One subject observed ferning throughout the menstrual cycle. One male investigator who tested the microscope observed ferning of his own saliva; similarly, Braat and colleagues found positive results for both men and postmenopausal women.
Guida et al. observed that saliva microscopy detected ovulation 36.8% of the time but that 58.7% of the results were uninterpretable. Saliva testing was found to be an option for detecting ovulation, but only after many samples were excluded because of unclear results. Freundl et al. reported a high rate of false-negatives (a low indicated level of fertility on days of high fertility). When considering the total number of fertile days within a cycle, the false-negative rates for three microscopes studied were 73.4%, 58.0%, and 51.6%.
Although home saliva microscopes are inexpensive and portable, the results can be difficult to read and interpret, and it is difficult to define the window of fertility. In general, this technique requires more steps, skill, and interpretation than other fertility-monitoring methods, and the results are not very reliable.
Saliva and cervical–vaginal mucus can be tested for electrolytic changes during the menstrual cycle by using a monitor that measures changes in electrical resistance. Zetek, Inc., manufactures an electronic saliva monitor for use at home and offers two models, the Cue II and the OvaCue. An optional vaginal sensor can be used in conjunction with these monitors to test vaginal mucus to confirm ovulation. Using the oral and vaginal data together provides information about the beginning and end of the fertility window. The OvaCue model is newer and has been upgraded for data storage; an optional software package is available for downloading data from the device for expanded analysis, charting, and tracking.
Oral saliva fertility monitoring (OSFM) is straightforward. The patient applies a spoon-sized sensor to her tongue for five seconds first thing in the morning. The monitor displays the patient's current cycle day, her current level of fertility, the window of possible fertility for this cycle, the time of maximum fertility, and whether ovulation has occurred. Fertility status is depicted by one to seven bars, indicating low to high fertility. The optional vaginal probe is required for ovulation confirmation. According to the manufacturer, when used exactly as recommended on consecutive days, OSFM can predict ovulation five to seven days in advance.[6,32] The OSFM device uses a patented technology called the Electrolyte Method. The monitor tests for changes in levels of electrolytes, such as sodium and potassium, in secretions. Salivary electrolytes reach a peak approximately seven days before ovulation. By measuring these electrolytes daily, OSFM can predict the LH surge and subsequent ovulation.
The LH surge is also associated with changes in electrolyte concentrations in vaginal secretions. After the LH surge, the cervical mucus becomes less viscous to give sperm maximum motility; therefore, electrolyte levels in the mucus temporarily drop. After ovulation, the cervical mucus returns to normal and there is a rise in vaginal electrolytes. The vaginal probe tests for this temporary dip and subsequent rise, confirming that ovulation has occurred and defining the end of the fertility window.[6,26] In studies, subjects were instructed to limit dietary sodium and the use of sodium-containing antacids during the testing window. Also, study participants were instructed to avoid sexual intercourse and douching before analysis.
Studies have reported conflicting results concerning the accuracy of OSFM for ovulation prediction. A 1988 study found no significant salivary resistance peak during menstrual cycles and concluded that the OSFM device tested was not useful for fertility monitoring.[32,33] In another study, an OSFM device with both oral and vaginal probes was tested in a sample of spontaneously ovulating infertile women. The correlation coefficient for the association between the peak in salivary electrical resistance and the serum LH peak was 0.61 (p < 0.01). However, the LH peak occurred four to nine days after the salivary peak. Urinary LH testing performed twice daily was the best predictor of ovulation (r = 0.93, p = 0.0001). In 1997, Moreno et al. reported that, on average, OSFM (the Cue) predicted ovulation eight days in advance. The method was found to be a reliable predictor of ovulation as part of natural family planning.
OSFM is more expensive than other options and requires a substantial initial investment by the patient. The vaginal probe and software are sold separately, so the customer can customize components. However, no test strips or other supplies have to be purchased, and the instrument can be used repeatedly. This technology does not require urine or saliva collection, and the results are clear and easy to interpret. However, the conflicting results in the literature raise doubts about accuracy and reliability for ovulation prediction.
The choice of a device for ovulation prediction depends on the couple's timetable for conception, desire for accuracy, comfort with technology, and willingness to pay. Pharmacists should review the patient's medical and medication histories to screen for any health conditions or medications that might interfere with the accuracy of results for the device being considered.
Patients must be educated on how to use the device and should understand the basic principles of the menstrual cycle, including viability of the ovum and sperm in the reproductive tract. The patient should know how to time intercourse to maximize the likelihood of successful fertilization.
Patients should always check expiration dates, and supplies should be stored according to the manufacturer's specifications.
Patients should understand that BBT and saliva testing must be completed first thing in the morning—immediately after waking and before eating, drinking, exercising, or brushing the teeth.
Urine tests must use the first urine of the day, which is the most concentrated urine and should provide the most accurate results. The test should be completed with the first voiding. If this opportunity is missed, the patient should avoid drinking too much fluid for four to six hours before a sample is collected.
If a urine test cannot be completed immediately, the patient should refrigerate the sample and bring it to room temperature before testing.
If the patient is using a vaginal sensor in conjunction with OSFM, the probe should be used in the evening before intercourse or douching.
Patients should understand that there are multiple causes of infertility. If a couple uses a product exactly as directed and does not conceive, a gynecologist or infertility specialist should be consulted for further assessment.
Am J Health Syst Pharm. 2008;65(4):299-314. © 2008 American Society of Health-System Pharmacists
Cite this: Devices for Home Evaluation of Women's Health Concerns - Medscape - Feb 15, 2008.