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Tracking Your Fertile Days

A guide to basal body temperatures, ovulation predictor test kits, and cervical fluid.

I get asked a lot of questions in my practice when working with patients to optimize their fertility. For example:

How come my basal body temperature chart does not line up with my increase in cervical fluid and a positive ovulation predictor test kit (OPK for short).”

 Or, “I don’t know when or if I’m ovulating so how can I possibly know when the right time to have intercourse is.”  

Or, “My cervical fluid changes and my temperature rises several days before I get a positive OPK.”  

You can see where I am going with this. It can be really tricky to determine when is the best time to conceive! The first step in the process is really getting to know your body. We are going to do a deep dive into how to properly read and assess your cervical fluid, basal body temperature chart, and your OPK and most importantly when is the best time to conceive.

What is an Ovulation Predictor Test Kit?

First it’s helpful to understand exactly what is an ovulation predictor test kit. This test will help determine when ovulation may be approaching. It measures the amount of luteinizing hormone, or LH, in the urine towards the end of the follicular phase. LH is is produced in the pituitary as the dominant follicle ripens, LH surges right before the egg is released. The OPK is best used between the hours of 10 a.m. and 8 p.m. and not using the first morning urine.  It’s also helpful to make sure you do not drink too much water beforehand as it will dilute the LH. Once you have a positive OPK you will likely ovulate within 12 to 48 hours. It is helpful to use the OPK in conjunction with the BBT (basal body temperature) especially if cervical mucus is not very strong.

What is your Basal Body Temperature or BBT?

Basal body temperature or BBT chart records the temperature of the body upon waking, a time when the body is deeply rested and metabolism and temperature is at its baseline. The temperature will begin to rise once a woman has ovulated and begins to produce progesterone. Historically, the BBT started in the Catholic religion in menstrual charting to detect the body’s rhythm. It’s helpful to have at least three months of temperature charts to see the consecutive changes in the temperature so you can see when the rise is occurring to track ovulation. All you need to take your BBT is a digital thermometer and a piece of paper, however now there are many great apps that you fill in your temp daily to see your monthly pattern. There are also trackers, like the Ava bracelet, that will do all the work for you. The temperature should be taken first thing in the morning before doing anything else. Note that temps are very sensitive to poor sleep, alcohol, and stress and will impact the temp each day. Temps will be most accurate when you have had three to four hours of consecutive sleep.

It’s important to note that BBT’s do not predict ovulation, they can only tell you that ovulation has already occurred. OPK’s will help you predict that ovulation will occur within the window of 12 to 48 hours. It is also helpful to know that hormone levels are constantly changing and LH can vary woman to woman in how long it remains at its peak. Some women experience mini-surges of LH prior to ovulation and some women don’t produce enough to be detected on the OPK but are still ovulating. Remember when I said to use the OPK it later in the day? This is because LH begins to rise in the morning so it will not be as strong as it is at 2 p.m., and the time your LH surges may vary. In some women it may last less than 24 hours.  if you’re only testing one time per day at 2 p.m. but the peak is occurring at 7 p.m., you will miss it. This is why it is important to test up to three times per day if you suspect you will be ovulating soon.

What is cervical mucus and how to I determine it’s quality?

Cervical mucus is another helpful sign to determine when ovulation is approaching.  Observing this will help you learn more about your body and when conception can take place.  There are four types of cervical mucus, G, L, S, and P. When estrogen peaks, it stimulates the production of cervical mucus, generally starting six days before ovulation. During the “dry” times of your cycle, when there is little moisture or fluid being produced from the vagina fertility is lower. This is when G type is present, it is impenetrable by sperm. As you approach ovulation, more liquid is produced moving from G to L type when the discharge will be more sticky and wet and finally to stretchy and slippery or egg white (S type). The S type mixes with the L type to make spinnbarkeit, or spinn. Next the mucus loses its stretch as the cervix produces P type that is very lubricative and slippery to aid the sperm during the most fertile day. It is helpful to recognize the changes in the fertile mucus because it precedes ovulation and can help you determine your most fertile days. The last day of cervical mucus is the peak day or best time for conceiving as it is the day of or day before the egg is released. Cervical fluids job is to help get the sperm inside the reproductive tract before the egg is released showing that the best time for intercourse is two days before ovulation.

A few final things to keep in mind. Previous birth control use may impair cervical mucus causing the body to only produce G type stopping the sperm from making it through the cervix despite ovulation occurring. Many medications can inhibit fertilization, this includes antibiotics, NSAIDs, antidepressants, antihistamines, and clomid.

How does Chinese Medicine fit in with tracking your fertility?

As an acupuncturist one of our greatest strengths is to see what is happening inside the body by watching or feeling what is happening on the outside of the body. This is done through taking pulse, looking at your tongue, a detailed intake, and palpation. In fertility, we look closely at the change in temperature throughout the whole cycle, not just during ovulation. We also discuss the cervical mucus, any symptoms that arise before menses and then what is happening during a woman’s bleed. All of these signs together can give us detailed information on how the body is performing and what may be happening hormonally. It is for this reason that the BBT will mean more to a Chinese medicine practitioner than to a Western specialist.  

Chinese medicine is also very beneficial to help encourage the body’s production of cervical mucus by nourishing blood and yin in the first half of the cycle (day 3 to 14) and by boosting yang in the second half (day 15 to the start of the period). If the cycles are irregular, it can also help to bring the cycle back to the optimal length of 26 to 33 days and can help regulate the temperature. When the temperature is too high or too low, it is a sign that something is out of balance. It will also detect what may be happening if either the follicular or luteal phase is to short or too long. If the follicular phase is too short, it is likely that the egg is unable to fully develop and if the luteal phase is too short it is likely there is insufficient progesterone to support a pregnancy. This can be treated by acupuncture and herbal medicine. Your practitioner will support you by treating you according to your cycle and recommending specific lifestyle and dietary changes as well as Chinese and western herbs to regulate the cycle and optimize fertility.  

I hope this guide helps you better determine how to track ovulation during your cycle!


Lyttleton, Jane. Treatment of Infertility with Chinese Medicine. Churchill Livingstone/Elsevier, 2013.


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