If you have a friend or family member trying to conceive, you may have once heard them mention that they are tracking their ovulation. Under this circumstance, they may be trying to plan the ideal time to have sex (i.e., when they are ovulating) in order to fertilize an egg and become pregnant. However, ovulation tracking can also be used to avoid pregnancy – although we note in advance that it is not as effective as most other methods of contraception, and you should definitely talk to your doctor before making this choice.

To learn more about this non-hormonal method and give you an overview of the major pros and cons, we turned to Sara Twogood, MD, a board-certified ob-gyn and Flo medical expert.

What is ovulation tracking as contraception?

Let us first make a small update on the definition of ovulation. According to the Cleveland Clinic, ovulation is when an egg is released from an ovary and moves down the fallopian tubes and into the uterus, where fertilization can occur if semen is present in the body. The health organization notes that this typically happens around day 14 of the menstrual cycle.

If you are tracking your ovulation for the purpose of avoiding pregnancy, says Dr. Twogood that the general idea is to avoid having sex four to five days before the day you ovulate, and approx. two days after ovulation. In other words, avoid sex during the time you are most fertile or likely to become pregnant. (Remember: although the chances are lower, it is also possible to get pregnant just before, during and after your period.)

She explains that the above time frame for intercourse avoidance is based on the idea that sperm can live in the female reproductive tract for up to five days plus the fact that an egg is viable for about 24 hours after you ovulate.

There are a few different ways you can track your ovulation, which are also called fertility awareness methods (FAMs). Dr. Twogood says that FAM’s guidelines are really conditional based on which method you practice. According to Planned Parenthood, a few FAMs include taking your temperature (with a basal thermometer), monitoring your cervical mucus, and using a calendar to track your ovulation days. The health organization notes that fertility awareness methods are the most effective when multiple FAMs are used together.

Tools like the above thermometer and menstrual tracking apps can be especially helpful here.

What are the potential pros and cons of ovulation tracking as contraception?

“There are many benefits to tracking the menstrual cycle and ovulation – more than just a potential use of contraception,” says Dr. Twogood. “When hormones change and change during the menstrual cycle, they can contribute to physical and emotional changes. Knowing where you are in your menstrual cycle leads to a better understanding of the female body in general!”

For example, knowing what day or phase you are in your menstrual cycle can help you understand why you are dealing with symptoms such as bloating, cramps, mood swings or chest tenderness.

When it comes to tracking ovulation as a method of contraception, says Dr. Twogood that some of the potential benefits are that it is inexpensive, does not require a trip to the doctor and non-hormonal, which can be a draw for some. “You can use it anytime, anywhere,” she adds.

However, there are very real disadvantages to using ovulation tracking when trying to avoid pregnancy and they should be seriously considered. Dr. Twogood says the use of ovulation tracking as contraception is only about 75 percent effective, meaning 25 percent of people can experience unintended pregnancy. When you compare it to an IUD (which is more than 99 percent effective) and the pill (about 91 percent effective), the lack of reliability is obvious, especially if you are trying to avoid pregnancy.

That said, if you are tracking your ovulation as your most important contraceptive, you can also use another method of contraception such as condoms – which are estimated to be 85 percent effective in preventing pregnancy and also helping protect against STIs.

But when ovulation tracking is performed perfectly, which means you have regular periods, do not have sex around the time of ovulation and have no accidents, Dr.Twogood says that ovulation tracking for contraception can be up to 95 percent effective. But again, there is a lot of room for error.

To begin with, not everyone has regular menstrual cycles or periods that arrive every 21st to 35th day and last two to seven days every single month, which can make it accurate to track the fertile period (and know when to avoid sex ) quite difficult. So when someone has an irregular menstrual cycle and they rely on this method to prevent pregnancy, says Dr. Twogood that the failure rate increases by “quite a bit.”

She also adds that people tend to have the highest libido (sex drive) when they ovulate. “This means that when sex drive is highest, there is a need for alternative contraception.”

Finally, she says that if you plan to use ovulation tracking as your form of contraception, both partners need to be on the same page for it to work more effectively.

If you are interested in tracking your ovulation for contraception, talk to your doctor to fully understand how to perform the method and what the individual pros and cons may mean for you.