Ovulation testing

by | Babies and Pregnancy

Ovulation testing is something you might consider if you are trying to get pregnant. Home ovulation test kits detect changes in the levels of hormones that happen during a woman’s menstrual cycle, indicating when you are likely to ovulate. This can help you to work out the best times to try to conceive.

Ovulation testing is also sometimes recommended by doctors if you are having trouble getting pregnant. If this is the case, blood tests are used to test whether or not you are ovulating.

What is ovulation?

Ovulation is part of the normal menstruation cycle, and happens about 14 days before a woman gets her period. It is the release of an egg (ovum) from an ovary; sometimes more than one egg is released from the ovaries.

Once an egg has been released, it enters one of the fallopian tubes and travels towards the uterus (womb). The odds of getting pregnant are highest when there are live sperm in the fallopian tubes at the time of ovulation.

front view of female reproductive system

Getting pregnant

Eggs can survive for up to 24 hours after ovulation. So a woman can become pregnant if an egg is fertilised by sperm within 12 to 24 hours of ovulation.

Because sperm can live for up to 7 days inside a woman’s reproductive tract (most sperm tend to live for about 3 to 5 days), it’s possible to conceive if you have sex any time from about a week before ovulation to 24 hours afterwards. But a woman is most fertile from about 5 days before ovulation to the day of ovulation – sometimes called the fertile window.

Predicting ovulation

Some women who are trying to conceive find it useful to try and pinpoint when they are likely to ovulate. Predicting their most fertile time may help improve the chances of getting pregnant. This is especially true in certain circumstances, such as if you or your partner travel frequently for work.

There are several ways of estimating when you are likely to ovulate that do not involve testing. These methods can be used together to help predict your most fertile days. They include:

  • Tracking your periods. Keep a diary, use a smartphone app or an ovulation calculator to work out how long your cycle usually is. If you have a fairly regular cycle, you can predict the time you are likely to ovulate by counting forward 14 days from when your next period is due.
  • Monitoring your cervical mucus (mucus made in your cervix). You may have noticed a difference in the amount and consistency of vaginal discharge you have at different times of your menstrual cycle. This is due to changes in cervical mucus, which becomes clear, slippery and has the consistency of raw egg whites during your fertile days. The mucus tends to become thinner and more watery around the time of ovulation. Noting these changes helps work out when you are most fertile.
  • Tracking your basal body temperature (temperature at rest). This involves using a thermometer to record your body temperature every morning before you get out of bed. Your body temperature should rise slightly around the time of ovulation. An accurate thermometer is needed (thermometers designed specifically for measuring basal body temperature are available from pharmacies), and you need to record the temperature daily to look for a pattern. The most fertile time will be the few days before your temperature rises.

In general, having regular sex (at least every 2-3 days) throughout your cycle, and particularly during the week before you ovulate, gives you the best chance of getting pregnant.

The diagram below shows what happens during a normal menstrual cycle, including the changing levels of hormones.

normal menstrual cycle

Home ovulation tests

There are several different home ovulation test kits (also called ovulation predictor kits) available in Australia. These tests use either a sample of urine or a sample of saliva to test for changes in a woman’s hormones that occur just before ovulation. Most tests detect an increase in either luteinising hormone (LH) or oestrogen, but at least one test measures the levels of both these hormones.

Urine tests for ovulation

Levels of of a hormone called luteinising hormone (LH) rise noticeably about 24 to 36 hours before ovulation and stimulate the release of an egg. Testing the level of luteinising hormone (LH) in the urine can help predict the timing of ovulation and when you are most fertile (which is between the time that the LH levels start to rise to the time that you ovulate).

One brand of ovulation test measures the urine oestrogen level as well as the LH level. (The oestrogen level also increases just before ovulation.)

Depending on the brand of test kit, you may need to collect a urine sample to dip the test strip into, or hold a test strip in your urine stream. The kit will contain several test strips, so that you can test your urine over several days. Some kits contain both ovulation tests strips and pregnancy tests strips.

Saliva-based ovulation tests

When a woman’s oestrogen level rises just before ovulation, the salt concentration in her saliva increases. This causes subtle microscopic changes that can be detected using saliva-based home ovulation test kits.

This type of test involves putting a small amount of saliva on a test slide and looking at it through a magnifying lens. Saliva that has a higher concentration of salt will crystallise into a fern-like pattern when it dries. This so-called ‘ferning’ appearance indicates a rise in oestrogen levels, and can be used to predict that you are about to ovulate. (Test kits contain pictures of saliva at fertile and non-fertile times for you to compare your samples with.)

Using home ovulation test kits

Always read the instructions carefully. Make sure that you start testing at the recommended time in your cycle, and check the best time of day to do the different tests.

Bear in mind that some medicines, including fertility treatments, can affect the results of some tests. If you have recently been pregnant that may also affect the test results. Talk to your doctor if you are not sure about whether these tests will be useful in your situation.

Urine test kits are generally considered to be more accurate than saliva tests. Neither type of test should ever be used as a form of contraception, as they would be very unreliable.

Advantages and disadvantages of home ovulation testing

Advantages: Ovulation test kits may be beneficial if you have slightly irregular periods or find other methods of tracking your fertility difficult or unreliable.

Disadvantages: Ovulation test kits can be expensive and there are no guarantees. There is currently no evidence that using ovulation test kits improves your chances of getting pregnant naturally.

Where can you get an ovulation test kit?

You can buy home ovulation test kits from chemists (pharmacies), some supermarkets and online. You do not need a prescription.

What if you are having trouble conceiving?

It’s recommended that you see your doctor if you are not pregnant after a year of trying. But see your doctor sooner rather than later if you have irregular periods, very painful periods or any health problems that may affect your fertility (such as endometriosis or polycystic ovary syndrome – PCOS). Women aged 35 years or older should see their doctor if they are not pregnant within 6 months.

Your doctor may recommend fertility tests if you are having trouble conceiving, including blood tests to check that you are ovulating. Some couples may be referred to a fertility specialist for further tests and treatment.

Blood tests for ovulation

A blood test measuring the amount of the hormone progesterone can be done in the second half of your menstrual cycle to check if you have ovulated.

The progesterone blood test is different from home ovulation tests in that it is not predicting when you are likely to ovulate, but rather testing whether ovulation has definitely occurred. It’s just one of several tests that can help work out whether you have any fertility problems.

Other blood tests, including levels of other hormones (including oestrogen, follicle stimulating hormone, luteinising hormone, thyroid stimulating hormone or prolactin) may also be recommended to look for possible causes of ovulation problems.

Talk to your doctor if you have any concerns about getting pregnant.