Ovulation Predictor Kits (OPKs)

Becoming a mother is a feeling that is second to none, and getting pregnant is the first step in that direction. If you have been trying for quite some time but are not getting the desired results, an ovulation predictor kit can help you out.


Ovulation is a natural process that denotes the release of eggs from your ovaries. Every month, many eggs mature inside the ovaries. The one which is the healthiest among them moves to the pelvic cavity, and from there, it goes to the fallopian tube.


The egg survives no more than 24 hours without fertilization (the union of egg and sperm).

A sperm can survive not more than seven days inside your fallopian tube. This is the only small window every month when you can conceive.

The sperm which has the ability to swim in a straight line is considered the healthiest one, and this is required for fertilisation. When trying for a baby, your partner needs to ejaculate every 3-4 days to produce such a sperm.

The chances of conception are the highest if the intercourse takes place in the first two days just before ovulation.

Most women take the help of ovulation predictor kits to determine the right days for intercourse. So, how do ovulation predictor kits help? Here is all you need to know about an ovulation predictor kit.

What Is an Ovulation Predictor Kit?

An Ovulation Predictor Kit (OPK) tells you when you are the most fertile. These kits work by detecting the surge in the production of the hormone called luteinizing hormone (LH) that happens a few days before ovulation. Luteinizing hormone and ovulation are closely associated. A surge in the production of this hormone is what triggers ovulation.

Timing the intercourse just a few days after the surge will increase your probability of conception as it is during this time that the egg and the sperm are close to each other. Using ovulation tests to predict fertility is very common among couples trying to start a family, as they identify your fertile window.

When To Take An Ovulation Test?

Ovulation Predictor Kits help you to understand when your fertile period would begin which is usually 17 days subtracted from the actual length of your cycle. So, if the length of your cycle is 28 days, start taking the ovulation test on the 11th day and continue for the next six days.

Types Of Ovulation Tests

There are different types of OPKs and they work in the following ways:

1. Test Strip Method

This is a very popular method of identifying one’s ovulation period. It consists of strips that you need to place into your urine stream directly. You may also dip the strip in a cup containing your urine.

2. Mid-Stream Method

This kit resembles home-test kits for checking pregnancy and the method of testing is more or less same as well. You have to place a few drops of your urine on the test strip and observe the colour change. You need to compare this colour to the base colour. Depending on this, you will be able to say if you have already crossed your ovulating cycle or it is a few days away. The darker the colour of the strip, the closer you are to your ovulation period.

Urine-based OPKs work by testing your urine to check the increase in the LH and this is something that happens only 1-2 days before you start ovulating.

It is important to note that LH in a small proportion is always present in your urine. However, this increases four to five times a few days before ovulation and this is what triggers ovulation. The ovulation cycle is when your chances of conception are the highest.

3. Salivary Ferning Kits

Another way of testing is the use of salivary ferning kits. These consist of a small portable microscope which you need to use and analyse your saliva to determine salt-content. The salt content in your saliva goes up when more oestrogen is secreted. The dried salt resembles fern-shaped crystals.

The ferning is visible one or two days before you start ovulating or a couple of days after it. This helps you understand your most fertile window. At other times, the salt dries without any particular shape.

4. Ovulation Calculator

An ovulation calculator is another tool that you can use. This calculator is available online, and you need to furnish few details like the first day of your last menstruation cycle and the length of your cycle. Once you enter these details, the calculator shows your fertile days to conceive.

What to Choose?

Urine-based tests offer 99 percent accurate results and are the best option for you to use at home. However, do not use these tests as a contraceptive as the results are not foolproof. Moreover, you can become pregnant for up to 24 hours after ovulation. There can be a surge in the secretion of LH, even without the release of eggs. There can be false alarms too before the real one.

Ferning does not give as accurate results as the urine-based tests. Moreover, ferning can take place if you are taking Clomid or similar fertility drugs during your menstrual cycle.

Regardless of the method you use, try and maintain an ovulation calendar so that you have a clear idea of the tentative days when you would be most fertile.

How To Use Ovulation Kit?

In the case of urine-based OPKs, collect your urine in a cup or bowl or place the strip under as you pee. You will observe a change in the colour of the strips which indicates whether there is a surge in the production of LH.

You can also make use of digital OPKs that show symbols to tell when you would be most fertile. A digital ovulation test is also quite popular.

The general instructions usually vary a bit. However, as a rule of thumb, it is important that you collect your pee between 8:00 in the morning and 10:00 at night. The ideal time is believed to be between 2:00 pm – 2:30 pm. Try and maintain a fixed time for testing every day.

How To Read Ovulation Test Results

To know how to read the test results, you first need to conduct the test in the proper way.

Try and collect your pee more or less around a fixed time every day. This will help you track changes more accurately. Also, do not collect the urine just after waking up. By doing so, you might miss the first day of surge in your luteinizing hormone. Drink fewer liquids for a few hours before taking the test, to avoid the dilution of the test results.

Make sure to read the result within ten minutes of conducting the test. While the positive result would not change, a few other coloured bands might start to appear. Throw away the ovulation test strips or cards after you have read the results.

If you are opting for the salivary ferning kit, you would need to take the test just after waking up, before you drink or eat anything. Make sure that the saliva you test is free from air bubbles. Place saliva on a slide or simply lick the slide. Wait till the saliva dries and use the microscope to check if it has formed any fern-shaped patterns.

Advantages Of Using Ovulation Kits

There are many advantages of using OPKs. Some of them are:

  • Ovulation kits offer nearly accurate results and they are more precise than any other method of identifying the ovulation period. If you do the test properly, OPKs are 97 percent effective in detecting the LH surge, which is used as a marker for ovulation.
  • Ovulation kits are also easy and convenient to use. Apart from the ease of use, you are also required to conduct the test during the middle of your cycle, the time when you are most likely to ovulate, meaning this is something that you do not need to do every day. In the case of other tests like basal body temperature, you need a daily commitment. Here, all you need to do is place a few drops of your urine on the strip or stick.
  • OPKs are also easily available. You can purchase these kits in your local pharmaceutical store and even supermarkets. You do not need a prescription for buying these kits.

It is always easier to conceive when you know when your fertile period is. This is more so when you and your partner have such routines that regular sex is a problem. You can schedule the intercourse in such a way that it falls within your fertile window.

Disadvantages of Using Ovulation Kits

Every coin has two sides. Ovulation kits have a few cons too and they are:

  • OPKs do not actually say whether you have ovulated or you are going to do so. They detect the surge in LH production which is thought to precede ovulation. There are times when an egg does not emerge from the follicle. This is referred to as the luteinized unruptured follicle syndrome.
  • OPKs are also not able to say whether your cervical mucus will be able to provide the sperm with a conducive environment to swim through. What you experience as vaginal discharge in the middle of your cycle is mucus secreted by the cervix that offers the sperm a fertile environment for fertilisation. OPKs cannot track whether this cervical mucus is optimal for conception or not
  • Ovulation kits do not work if you are on fertility drugs. OPKs do not give proper results when your system has fertility drugs like Pergonal.
  • Ovulation kits also do not actually come cheap. The branded ones (which you should use for accurate results) are quite expensive and often one kit is not enough.
  • OPKs do not work well for women who are above 40. Women who are nearing menopause already have a high concentration of LH in their urine all the times. Thus, OPKs fail to give proper results.
  • Hormonal changes, cysts, and even fertility medications can lead to ferning even when you are not ovulating. Also, you are required to take the ferning test several times in a day and you need to plan them around your meals. This can be a problem.

So, there are both advantages and disadvantages associated with ovulation predictor kits. The advantages obviously outweigh the disadvantages. This is the reason why millions of future moms are using this kit to help them conceive. OPKs offer better results when teamed with monitoring drugs.

Unless you are above the age of 40 years, you can easily use these kits to identify the days in your cycle when you will be most fertile.

What Else To Know?

Common drugs like paracetamol do not affect the results of this test. However, as already mentioned, this test does not work if you are taking medicines that contain LH or human chorionic gonadotrophin.

Many brands offer ovulation test kits and you can even order these kits online. Make sure you look for a trusted one. Talk to friends or relatives who have already used these kits and conceived. Happy conceiving!