Ovulation Test: What is the Right Time to Take One?

Are you using a urine-based ovulation test to determine when you ovulate? Before you go through all that effort, it’s important to make sure you’re using it correctly. Here are answers to the most common questions about ovulation tests.

What is an ovulation test?

An ovulation test (also sometimes called an OPK, which stands for ovulation predictor kit) is a test that detects the presence and concentration of luteinizing hormone (LH) in your urine. About 12 – 36 hours before ovulation, there is a brief surge in LH levels. (The length of time between the beginning of the LH surge and ovulation varies from woman to woman.) The LH surge sends a message to your ovaries that it’s time to release an egg: ovulation! When you get a positive ovulation test, it means that ovulation is likely imminent.

How soon after a positive ovulation test will I ovulate?

Most women ovulate between 12 – 36 hours after the first positive ovulation test. Since the surge can sometimes last for a day or two, testing every day—or even twice a day, once in the morning and once in the afternoon—can help provide context for where in your surge you are.

What time of day should I take an ovulation test?

It can be confusing to know what time of day is best to take an ovulation test. Some tests require testing with your first morning urine, and other tests require testing with afternoon urine. It’s best to follow the instructions on the brand of test that you’re using.

The LH surge usually occurs in the morning, but it can take several hours for the hormone to appear in urine. This is why many brands of ovulation tests ask you to test in the afternoon.

Another factor to consider is the length of your LH surge. Some women have an LH surge that lasts for a few days, and other women have a surge that lasts only a few hours. Both are fine, but the latter is harder to detect if you’re only testing once a day in the morning. Many women find that they can only get a positive ovulation test when they test twice per day, once in the morning and once again in the afternoon.

What’s the right way to take an ovulation test?

  1. Follow the instructions on the package—different brands of tests have different instructions.
  2. Don’t drink excessive fluids before testing.
  3. Try not to urinate for at least four hours before testing.

When in my cycle should I start testing?

That depends on which type of test you’re using. Clearblue OPKs work by measuring changes in hormone levels from your personal baseline. In order to do this, you need to start using Clearblue tests before your LH surge begins. Follow the directions on the package insert to determine what day of your cycle, depending on your average cycle length, to start testing.

Don’t be tempted to use fewer testing sticks by starting your testing later in your cycle. If you miss the non-fertile days of testing, you will not be able to accurately identify the fertile days. For this reason, it’s also important to use one and only one test base per cycle.

The less expensive tests, like Wondfos, tend to work by looking for an absolute threshold of LH in your urine. This means that it’s not as important to start testing early. You want to test early enough that you won’t miss your LH surge, of course, but since the test isn’t establishing any kind of baseline, testing before the surge is not strictly necessary.

I have a long/irregular cycle. How do I know when to start testing?

The best thing to do is decide when to start testing based on the length of your shortest cycle in the past six months. Then, continue testing until you detect a surge. If your cycle varies by a week or so, you can expect to go through up to 10 tests. The more your cycle varies, the more tests you’ll go through.

Does a positive OPK mean you ovulated?

Not necessarily. An OPK detects signs that your body is preparing to ovulate, but that doesn’t mean you will definitely go on to ovulate. Some women’s bodies gear up to ovulate several times in the same cycle, but lose steam before the egg is actually released. If you have PCOS, hypothalamic amenorrhea, or just an irregular cycle, this might be happening to you. If this is the case, it’s particularly important to be aware of the fact that a positive OPK does not mean that you will ovulate. BBT charting can help confirm when ovulation actually happened, but only retrospectively. You’ll need to do it consistently for the entire month in order to get results, and even then it might not work.

I keep testing and never seem to get a positive result. Why?

There are a few possible explanations for why you might not be getting a positive result:

  • You have a short LH surge. If your LH surge is on the short side, it’s possible to miss it if you’re only testing once a day. Try testing twice per day for one cycle.
  • You have a very long cycle. If your cycle is on the longer side, you might have started testing too early.
  • You didn’t ovulate. The most obvious reason for not getting a positive OPK is that you didn’t ovulate. This can be due to a variety of factors, such as stress, illness, or hormonal conditions.
  • Malfunctioning tests. If you’re using the inexpensive online tests like Wondfos, you need to be careful about counterfeit tests. Wondfo OPK packages should be blue, with the word “Wondfo” in the drop logo. The testing strips should have a blue handle with the letters “LH” in darker blue.

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