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The best at home tests to predict ovulation in women with PCOS are Ovulation Predictor Kits (OPKs) and the cervical mucus method. These tests however are not perfect and do not confirm ovulation like ultrasound.
To confirm ovulation, the best at home tests are progesterone specific tests or core body temperature.
To understand why one ovulation test is better than another, for women with PCOS, some basic knowledge of the menstrual cycle is helpful.
The Menstrual Cycle
Normally at the start of the menstrual cycle, follicle‐stimulating hormone (FSH), luteinizing hormone (LH) and estrogen levels start low. During this (follicular) phase, a dominant follicle begins to emerge and secrete high levels of oestrogen. This causes a surge in LH (and FSH) which triggers ovulation, i.e. the release of a mature egg from the follicle.
After ovulation, LH and FSH slowly declines back to initial levels and the follicle transforms into a corpus luteum which secretes progesterone along with estrogen. This helps prepare the endometrium for embryo implantation and supports development of early pregnancy.
Similarly, basal body temperature (BBT) also changes throughout the menstrual cycle. Shortly after ovulation, BBT increases to between 36.4°C and 37°C. BBT will then drop if pregnancy doesn’t occur, to help induce the uterus lining to shed. A similar rise is also seen in a woman’s core body temperature (i.e. temperature of body’s internal organs). Specifically, core body temperature is 0.4°C to 0.7°C higher in the post-ovulatory luteal phase, than during the pre-ovulatory follicular phase.
Changes in the cervical mucus is also seen across the menstrual cycle. Pre-ovulation cervical mucus is low in quantity, whitish, thick and inelastic, hampering the entry and movement of sperm. However during ovulation, cervical mucus increases in quantity, is clearer, elastic and slippery. This naturally assists sperm cells to enter the uterine cavity at the optimal time in a woman’s cycle.
It is well-established that women who keep track of these physiological changes, and determine their fertility window, are more likely to become pregnant per cycle.
However, tracking these changes is not so straight forward, especially in women with PCOS.
The 5 most common ovulation tests are:
- Ovulation Predictor Kits (OPKs)
- Basal Body Temperature
- Core Body Temperature
- Cervical Mucus
Learn more about each of these tests below and why some are better than others for women with PCOS.
Ovulation Predictor Kits
|Limitations||Requires trial and error to find optimal LH threshold|
Ovulation Predictor Kits (OPKs) are used to identify the surge of luteinising hormone (LH) that precedes ovulation. This is particularly useful in women with irregular or longer than normal menstrual cycles.
However, OPKs do not actually predict the day of ovulation. This means couples still need to do the deed several times following an LH surge to maximise their chances of pregnancy.
In women with no underlying factors, daily testing for an LH surge is consistently more accurate than basal body temperature at predicting imminent ovulation.
However in women with PCOS, the accuracy of this method is questionable due to the overproduction of LH. Although not all women with PCOS have elevated LH levels. Fortunately, experts agree that the LH surge (and not LH peak) is the better predictor of ovulation. This means selecting OPKs with an LH threshold well above your baseline levels will minimise false positives.
Although, even in the best case scenarios, OPKs are less than perfect. Specifically, OPKs fail to correctly predict ovulation (within 24 hours) in approximately 33-50% regular menstrual cycles. Hence the need to do the deed more than once after a positive OPK.
This is also why fertility experts usually suggest combining OPKs with other ovulation tests, such as peak-type cervical mucus, to better predict ovulation at home.
Nevertheless, women with PCOS keen to use OPKs are recommended to consult their doctor to determine baseline LH levels and discuss how OPKs may be suitable.
Basal Body Temperature
|Limitations||Highly variable temperature reading.|
Using basal body temperature (BBT) as a method to identify the ovulation time is an easy, inexpensive, and self-administered method. This is made possible due to the thermogenic (heating) effect of progesterone on the body.
In the first half of the menstrual cycle (follicular phase), BBT stays between 36.1 and 36.7°C. However, approximately 1 day before ovulation, coinciding with peak estrogen levels, BBT drops to its lowest point in the cycle, also known as nadir.
In the second half of the menstrual cycle (luteal phase), shortly after ovulation, the corpus luteum begins secreting progesterone. This causes BBT to slowly increase 1-2 days later, by approximately 0.5 to 0.8°C, where it then remains for the majority of the luteal phase.
Eventually, the corpus luteum begins to regress in the later part of the luteal phase and serum progesterone levels decrease. This causes BBT to return to initial levels over the next 1-2 days, just prior to the onset of menstrual bleeding.
In this manner, the biphasic pattern of BBT can retrospectively indicate ovulation.
However BBT is also affected by many factors other than hormonal changes, such as fever, alcohol, emotional or physical stress, sleep disturbances and a change in waking time.
To complicate matters more, its been reported that some women may ovulate without a clear rise in temperature. Therefore, the use of BBT as a method to predict ovulation is not entirely reliable.
Of the 5 ovulation tests listed here, studies consistently show that BBT is the least accurate method to detect ovulation.
Even the introduction of wearable electronic devices, with continuous temperature measurement failed to dramatically to improve the accuracy of this method.Source: Zhu T Y, et al. (2021)
Core Body Temperature
|Limitations||Retrospective and invasive test.|
Core body temperature refers to the temperature of the body’s internal organs, such as the heart, liver and brain. Among these organs, the hypothalamus deep within the brain, is considered the gold standard for core body temperature. However, studies also show that esophageal, rectal, vaginal and gastrointestinal temperature all correlate well with the true core body temperature.
During a woman’s menstrual cycle, core body temperature varies according to hormonal changes. In particular progesterone, which has a thermogenic (heating) effect on the body.
In short, 24 to 36 hours after ovulation progesterone levels begin to rise. This then causes core body temperature to rise some 24 hours later (i.e. 48 to 60 hours after ovulation). Over the next 24 hours, this rise in core body temperature eventually plateaus and sits somewhere between 0.3°C to 0.7°C higher than normal (i.e follicular phase core body temperature) for the majority of the luteal phase. Eventually towards the end of the luteal phase, the corpus luteum begins to degenerate and progesterone levels decline causing core body temperature to drop down to preovulatory levels.
This well-studied change of core body temperature over a menstrual cycle allows women (and experts) to estimate the day of ovulation retrospectively.
Not surprisingly, studies assessing the reliability of vaginal based temperature sensors (OvuSense and OvulaRing) for ovulation tracking, report high accuracy (>95%) even in women with irregular cycles and PCOS.
Interestingly, manufacturers claim this technique along with proprietary software, can predict the fertile window of users in advance. However no evidence to date has been published which supports this claim among women with irregular cycles and or PCOS.
Theoretically, the increase in estrogen (or estrogen:progesterone ratio) just before ovulation causes a slight fall in core body temperature. However this phenomenon does not occur consistently enough in women to be considered a reliable indicator of upcoming ovulation.
|Limitations||Requires optimal hormone levels.|
The appearance of cervical mucus, secreted by cervical and endocervical glands, varies throughout the menstrual cycle.
Outside of the periovulatory (ovulation) period, cervical mucus appears scant (minimal), viscous (thick) and white (or cloudy) in colour. As ovulation approaches, and estrogen levels begin to rise, cervical mucus increases in quantity, becomes less cloudy and more sticky. This change continues to the day of ovulation, when cervical mucus is most abundant, clear, slippery and/or stretchy (≥ 3 cm).
In women with regular cycles, tracking cervical mucus predicts ovulation with similar accuracy to OPKs (LH surge). While, both methods (cervical mucus and OPKs) are more accurate than BBT.
However, in women with PCOS, cervical mucus is altered structurally according to hormone levels, specifically oestradiol and progesterone.Source: Vigil P, et al. (2009)
In this study, women with PCOS and ovulatory cycles, had slightly higher progesterone levels but similar oestradiol levels to control women during the periovulatory (ovulation) period. Under high resolution microscopy, cervical mucus from these women appeared the closest in ultrastructure to control women, although pore diameter was significantly smaller (8.4 vs. 15 μm). On the contrary, women with PCOS and anovulatory cycles, had significantly reduced levels of oestradiol compared to controls, and a more denser ultrastructure (average pore diameter 1.8 μm) which would naturally impede sperm movement.
This explains somewhat why most women with PCOS report their cervical mucus to be more sticky and less elastic than non-PCOS women.
With that said, tracking cervical mucus is still very likely to predict when hormone levels are optimal for ovulation among women with PCOS, trying to conceive naturally, without any mediation or supplements.
For greater accuracy, this method should be used in combination with OPKs or progesterone based tests.
Just 24 to 36 hours after ovulation, progesterone levels begin to rise naturally before peaking around the mid-luteal phase (or 7 days before menstruation). Specifically, progesterone levels ≥16 nmol/l (or ≥5 ng/ml) during the mid-luteal phase indicates ovulation has occurred.
This is the primary method Doctors use to assess subfertile women for ovulation. However this requires taking a blood sample during the correct day of a woman’s mid-luteal phase.
In women with PCOS or irregular cycles, several blood samples may need to be taken every 5 or so days with this method to ‘catch’ the mid-luteal phase.
An alternative to blood sampling is pregnanediol-3a-glucuronide (PDG). PDG is the major urinary metabolite of post-ovulatory progesterone. This means urine sampling post-ovulation for PDG can also confirm ovulation under certain conditions.
Specifically, 3 or more consecutive days of PDG levels above 5 μg/mL, after the first day of a positive urinary LH test (threshold ≥20 mIU/mL) OR the end of peak-fertility type cervical mucus, confirms ovulation with no false positives (100% specificity). However studies clearly show PDG testing is not perfect, missing approximately 5 to 15% true ovulations, i.e. 5 to 15% false negative results, compared to progesterone blood tests.
HOW DO I KNOW IF I’M OVULATING WITH PCOS
Ovulation in women with PCOS is usually confirmed with a progesterone blood test 5 to 7 days after suspected ovulation. Some Doctors may also use transvaginal ultrasound to definitively confirm ovulation in women with PCOS.
A Tip From Fertility Science
As you can see, other than a progesterone blood test or transvaginal ultrasound, no at home tests will predict or confirm ovulation with the same accuracy.
Each type of at home ovulation test has inherent strengths and weaknesses. Using a predictive type test (OPKs) and a confirmation type test (PDG or core body temperature) together significantly increases this accuracy.
On a related note, if you find you are not ovulating at least 2 out of 3 cycles, or have been trying to conceive for over 2 years, please go and speak to a Doctor specialising in PCOS.
There are an infinite number of ways nowadays to manage PCOS, naturally and or with medication, according to your specific phenotype. In fact, you may feel better and find it easier to conceive when your body is in harmony.
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Bouchard T P, et al. (2019). Pilot Evaluation of a New Urine Progesterone Test to Confirm Ovulation in Women Using a Fertility Monitor. https://doi.org/10.3389/fpubh.2019.00184
Leiva R, et al. (2019). Pilot observational prospective cohort study on the use of a novel home-based urinary pregnanediol 3-glucuronide (PDG) test to confirm ovulation when used as adjunct to fertility awareness methods (FAMs) stage 1. https://doi.org/10.1136/bmjopen-2018-028496
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