Charting Your Fertility Cycle

Medically Reviewed by Traci C. Johnson, MD on February 11, 2024
7 min read

If it's taking you a while to get pregnant, a good way to raise your odds is to chart your fertility cycle. When you do this, you can find the best chance to make it happen.

As you go through your cycle, your body gives all sorts of clues to show when you ovulate. You just need to know how to look for them.

As part of charting, you'll need to:

  • Test to find out if and when you are ovulating.
  • Take your "basal body temperature" -- your temperature when you're at rest.
  • Examine your cervical mucus.
  • Track when your menstrual period begins.
  • Note when you have sex.

Knowing this information can make a difference. Though the average couple conceives after about 5 or 6 months of trying, people who know how to find out if and when the woman ovulates, or releases an egg, and who have sex regularly during that time improve their odds of getting pregnant.

Home tests and devices offer you a different way to monitor your fertility cycle. Some people use these alongside traditional techniques, while others use them as a substitute.

Ovulation predictor kits (OPKs)

You can find these at most drugstores. They cost about $25-$75 a month. These kits test the presence or the amount of luteinizing hormone (LH) in your urine. Some detect both LH and estrogen levels. This indicates ovulation will happen. When the surge is detected, having sex in the next 24-36 hours will improve your chances of getting pregnant. Because sperm will survive for some time inside of you, they'll be ready to join the egg during ovulation.

The kits have enough test strips to let you check your LH levels several times during your menstrual cycle. Start testing a few days before you think you might ovulate, then repeat a few times over the next few days to pinpoint the exact day. When your LH levels are highest, you're in the fertile window.

Progesterone ovulation tests. You can find this in drugstores or order online for about $40 a month. They test the level of progesterone metabolite in your urine over several days. The metabolite levels typically rise 24-36 hours after you ovulate, so finding a progesterone metabolite in your urine can signify that you have ovulated.. 

Saliva or “ferning” microscopes. These are small microscopes -- sometimes designed to look like lipstick cases -- that examine a sample of your saliva. As estrogen levels build up as you head toward ovulation, salt levels in your saliva increase, too. When you look at the saliva under a microscope, the salt causes a pattern that's like the leaves of a fern plant.

Manufacturers claim this method lets you predict your ovulation by 24-72 hours. They cost about $30 to $50, and, unlike many other tests, you don't need to buy additional expensive supplies. But studies have not found them all that reliable. They don't seem to work for everyone, and the results can be hard to interpret.

Fertility monitors

They can be expensive, but they have a significant benefit. While most ovulation predictors only give you a fertile window of up to 2 days, these can show 6-7 days of potential fertility for each cycle.

Fertility monitors give you more days to try to conceive, and they give a more accurate day of ovulation. Fertility monitors collect data from your body and your cycle. They use data and algorithms to help you determine exactly when you're going to ovulate. They're 89%-99% accurate in identifying your fertile window if used correctly. They monitor various signs of fertility, including skin temperature, basal body temperature, and vaginal fluids.

Though all these tests and devices may be helpful, keep in mind that they aren't perfect. If you have a medical condition like polycystic ovary syndrome (PCOS) or take medications, they may not give accurate results. Since there are so many ovulation tests and monitors out there, it's always a good idea to ask your doctor which one you should try.

Checking your basal body temperature is a way to predict when you ovulate, and it has helped women get pregnant. But recent research has shown that it may not work as well as experts previously thought.

Before you ovulate, your basal body temperature is usually about 97 to 97.5 F, although those numbers can vary from person to person.

During ovulation, your body releases the hormone progesterone, which brings on a slightly raised temperature a day or two later -- usually by 0.5 degrees. Your temperature will probably stay high until your next cycle begins. If you become pregnant during that cycle, your temperature will stay up beyond that.

That half of a degree difference may not seem like much, but it counts. Also, keep in mind that your temperature change happens after ovulation, which means that once it goes up, you've probably already missed your chance to become pregnant in that cycle. But by charting your temperature every day over several cycles, you may start to see a pattern that lets you predict when you are most fertile.

Begin taking your temperature on the first day of your period. You will need a thermometer that measures by tenths of degrees.

Make sure you take it about the same time every day, preferably before you get out of bed in the morning.

Don't do anything -- eat, drink, smoke, or even move around -- before you take your temperature.

You can take your temperature however you want -- orally, rectally, or vaginally -- but make sure you use the same technique each time.

Write down your temperature every day on your fertility chart. You can make a graph, with each day of your cycle on the bottom and temperatures on the left, connecting the dots as you go.

Keep in mind that you will probably get some occasional freak readings -- either high or low temperatures -- that don't fit into the larger pattern. If they don't happen often, don't worry about them.

After a few months, you may begin to see a pattern that shows when you usually ovulate. You may want to have your doctor look at the chart to help you interpret it.

Although charting is widely used, it isn't foolproof. Some women may not see a clear pattern emerge in their temperature. Since ovulation can happen at different times in your cycle from one month to the next, your chart may not predict when you'll ovulate.

Although it may take some detective work -- and may be a little off-putting to some -- learning how to spot changes in your cervical mucus is an easy and effective way to predict when you ovulate. One study says it's more accurate than charting your basal body temperature, although you can also use it at the same time.

Here's how it works: The mucus released by your cervix, a neck of tissue that connects the vagina and uterus, has different purposes. When you're not ovulating or getting near ovulation, your cervical mucus prevents sperm from getting into your uterus when you couldn't become pregnant anyway.

As you near ovulation, your cervix releases more mucus. When you are most fertile, your cervical mucus is stretchy and clear, like egg whites. At this point, it protects the sperm and helps them in their journey toward the egg.

For women with a 28-day cycle, the pattern of changes in their cervical mucus could look something like this:

  • Days 1-5: Menstruation happens.
  • Days 6-9: Vagina is dry with little to no mucus.
  • Days 10-12: Sticky, thick mucus appears, gradually becoming less thick and more white.
  • Days 13-15: Mucus becomes thin, slippery, stretchy, and clear -- like egg whites. This is the most fertile stage.
  • Days 16-21: Mucus becomes sticky and thick again.
  • Days 22-28: Vagina becomes dry.

But your cycle could be very different from this pattern, which is why it's useful to mark changes on your own fertility chart.

Ideally, you should check your cervical mucus every day, possibly every time you go to the bathroom. If you rub some toilet paper or your fingers -- after washing your hands -- over the opening of your vagina, you should be able to find cervical mucus. Examine the color and consistency between your fingers, and write down what you find.

Another way to learn about where you are in your fertility cycle is to check the position of your cervix. If you put two fingers into your vagina, you should feel the cervix at the end. Before you ovulate, it should feel hard and dry, like the tip of your nose.

During ovulation, you should notice that it seems to have shifted higher and that it feels softer and wetter. But you should always make sure that your hands are clean before you start poking around. And since it may be hard to tell exactly what you're looking for, you may want to talk to your doctor first.