In order to get pregnant, it is critical that the egg and sperm meet at exactly the right time. Ovulation tracking can help a couple plan intercourse around her most fertile time of the month. It has become big business and there are many different options out there to choose from. As a fertility doctor, I have some patients who tell me they are using multiple different test methods simultaneously! I thought it would be appropriate to discuss the most fundamental part of a woman's fertility: ovulation.
Men don't have to worry much about timing. Sperm can live in a woman's body for at least three days, sometimes up to five days. This is partly because a normal sperm sample contains more than 15 million sperm, leaving lots of spares if some start to die. Eggs are much more fragile. First, because there is typically only one egg released from the ovary (ovulated) each month. Second, eggs do not last long. After the egg is released, it is ready for fertilization in about 20 minutes and it remains useable for the next 12 to 24 hours.
Here are the best ways to tell if you're ovulating:
Cycle tracking, otherwise known as the "calendar method," is one of the oldest means of timing ovulation. It is based on the principle that after an egg is released, the sac that it came from is transformed into a temporary type of cyst called a corpus luteum (CL). The CL makes a hormone called progesterone, which is responsible for keeping the uterine lining healthy to allow a pregnancy to implant and grow. The CL only lasts for 12 to 14 days. Therefore, if you count backwards 14 days from the first day of your period, you can estimate when you would have ovulated. For example, if your period comes every 30 days, then you likely ovulate around day 16 to 18. This method only works for women who have regular periods that are 21 to 35 days apart. If your cycles are outside of this range, then a fertility doctor can help figure out how to get you to ovulate more regularly.
There are countless apps available for iPhone and Android that allow a woman to enter information about her cycles. These are handy because they often allow you to set reminders about upcoming events, such as fertile days and periods. Apps are basically the high-tech version of the calendar method described above. Basic cycle-tracking apps are not personalized, meaning that they assume you have a 28-day cycle with ovulation on day 14. More sophisticated apps can take into account varying cycle lengths and try to estimate your fertile days based on your past history.
A fertility doctor can help find an alternative method.
Ovulation predictor kits
Ovulation predictor kits (OPKs) are available online and in drugstores. They use urine samples to detect the hormones associated with ovulation. (The first pee in the morning is usually optimal because it is the most concentrated). In my opinion, the simplest OPKs are the best. These are the strips that contain two lines aimed at detecting the luteinizing hormone (LH) surge. The LH surge is the hormone signal from the brain that tells the ovary to release an egg. From the start of the surge until ovulation is typically 34 to 36 hours. In total, LH is detectable for no more than 48 hours in most women. So, if you detect ovulation with an OPK, then intercourse is best timed that day or the next day. The sperm should be waiting for the egg!
Digital ovulation kits look for two hormones: estrogen (E3G) and LH. They are designed to indicate when an egg is making a high amount of estrogen as it nears ovulation. This can span several days over a woman's "fertile window," culminating in the detection of the LH surge. Both types of OPKs are accurate, but they don't work for every woman. About 10 to 15 per cent of women experience difficulty with these kits. A fertility doctor can help find an alternative method.
Basal Body Temperature
Basal body temperature (BBT) charting involves using a sensitive thermometer (one that can measure 0.1 degree Celsius increments) to chart your temperature daily. The temperature reading should be taken orally, first thing in the morning before any activity or food. BBT graphs are available online and through apps to help you record the results. After ovulation, progesterone causes a slight increase in temperature of about 0.5 degrees Celcius. Therefore, once your temperature has risen you may have passed the most fertile days. BBT charting is best used to understand your cycles and plan for future months. It can be recorded in conjunction with cervical mucous, which is normally slippery like egg-whites around ovulation and becomes thicker once progesterone is made. "Mittelschmerz" is the medical name for the pain some women can feel during ovulation.
Your doctor can order blood tests to detect ovulation. The most common blood test is progesterone level. It is typically ordered in the third week of the cycle around day 21 to 23. A level above 10 nmol/L (Canadian units) is evidence of ovulation. Don't read too much into your absolute level! Progesterone is released in pulses after ovulation, so even numbers that seem 'low' might be perfectly normal.
Luteinizing hormone (LH) can also be detected at high levels in the blood for the 48 hours around ovulation. This test is not commonly performed however, because it requires frequent trips to the laboratory for blood testing, and interpretation by a doctor.
In summary, ovulation testing can be very helpful for couples that want to take a proactive approach to their fertility. They do not have to be performed every month. Once you understand the pattern of your ovulation then you may want to stop testing. Some of my patients find ovulation testing frustrating, costly and stressful. If this is the case for you, then ask for help from your doctor.
Also, keep in mind that these tests are meant to be a general guide about ovulation timing only. There are other factors that are important for fertility such as egg quality and sperm count. If you are under 35 then it is reasonable to try on your own for at least a year before seeking help from a fertility doctor. If you are over 35 then we suggest six months and women over 40 should seek advice right away. Every woman is unique! See your doctor to help personalize your fertility plan.
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