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How to Chart Your Fertility Cycle

Getting pregnant can be difficult, but charting your fertility cycle is one of the easiest ways to increase your chances of success. Read on to learn the methods that will help you figure out when you’re fertile.

Typically, if a couple is trying to get pregnant, they will conceive successfully within 5 to 6 months of having unprotected intercourse. However, much of this success depends on timing the intercourse correctly so that it occurs during the fertile period of the woman’s menstrual cycle. In order to maximize your chances of conception, we recommend taking the time to chart your fertility cycle to discover when you are most likely to get pregnant. 

Why to Chart Your Fertility Cycle 

There are only a few days in a woman’s menstrual cycle during which she can get pregnant. For most women, the menstrual cycle lasts 28 days, out of which there are only six days when conception is possible: the five days before ovulation (when an ovary releases an egg) and the day of ovulation itself. If you are looking to get pregnant, charting your fertility cycle and knowing when you are actually able to be impregnated will increase your chances of successful conception. 

How to Chart Your Fertility Cycle 

There are a number of ways to chart your fertility cycle. The three main methods for determining when you are able to get pregnant are often referred to as the Fertility Awareness Methods (FAM) and they can be used both to help induce pregnancy and to try to prevent it. The FAMs rely on measuring physical expressions of your fertility cycle that are based on the estrogen and progesterone in your body, which can help you determine which of the three stages of the fertility cycle (the preovulatory infertile phase, the fertile phase, and the postovulatory infertile phase) you are in. 

One method for charting your fertility cycle is by tracking your menstrual cycle. It is good to do this for several months given that it is common for a cycle’s length to vary slightly from month to month. Count the first day of your period as day one and then determine the duration of each cycle. Once you have data from several months, you can calculate when you are likely to be fertile by subtracting 18 days from the length of your shortest cycle to determine the first day that you’re likely to be fertile, and then subtracting 11 from the length of your longest period to determine the last day that you’re likely to be fertile. Having unprotected intercourse during this window will increase your chances of getting pregnant. 

A second FAM method is measuring your basal body temperature (BBT). This involves measuring your temperature as soon as you wake up every morning, before you even get out of bed, so as to get your most accurate base body temperature. By recording your BBT every morning, you can see the subtle temperature changes that indicate that your body has released an egg. These temperature changes are a product of the progesterone that is released when the egg is released, which raises your temperature by around 0.5 degrees. This method is good for seeing when ovulation is occurring, but it takes a while for it to be useful given that by the point that a temperature increase is registered, the egg has already been released. However, over time, you may find a pattern in your BBT that indicates when ovulation is approaching, which can be very helpful given that a woman is most fertile in the 1 to 3 days before ovulation and in the 12 to 24 hours after. 

The final FAM method involves monitoring the mucus produced by the cervix, the section of tissue that combines the uterus and the vagina. The cervix produces mucus before and during ovulation that is meant to protect the sperm and help it reach the egg. This method involves using either a tissue or your fingers to feel the mucus in your cervix several times per day and check its consistency and color. In the days before ovulation, when you are most fertile, the mucus will be clear, stretchy, and slippery — a bit like the consistency of raw eggs. While this method requires a little bit of detective work, this is an easy and effective way to predict ovulation. 

In addition to these methods, you can also chart your fertility cycle using relatively inexpensive devices that can be purchased at drug stores. Ovulation Predictor Kits (OPKs), which test for the amount of Luteinizing hormone (LH) in your urine (the levels of LH in your urine surge in the 12 to 36 hours before you ovulate), are 90% effective at predicting ovulation. Fertility monitors are also an effective tool that uses urine to chart fertility. They are a little more expensive than OPKs, but they have the added benefit that unlike other charting methods that give you a fertility window of approximately two days, fertility monitors give you six to seven days of potential fertility per cycle. 

With all of these methods, it is helpful to consult with a specialist to assist you in interpreting the data you’re tracking to ensure you have the best chance of successful conception. If you’re looking to start charting your fertility cycle, schedule an appointment with a fertility specialist at AFCT to see how we might be able to help you conceive. 

Scientific Research

Luteinizing hormone–independent rise of progesterone as the physiological trigger of the ovulatory gonadotropins surge in the human

Fertility and Sterility
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Recipient outcomes in an oocyte donation programme: should very young donors be excluded?

RBMO Oocyte Donation Programme
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