Ovulation Predictor Kits


The trigger that causes ovulation to occur is the increased release of luteinizing hormone (LH) from the pituitary gland. Before ovulation, the LH levels are low. At some point, the LH levels begin to rise rapidly. This is called the LH surge. The duration of time that the LH levels are high is about 48 hours from start to finish. Release of the egg from the ovary (ovulation) happens about 35 to 44 hours after the onset of the surge. The LH in the blood is eventually filtered through the kidneys and therefore causes levels in the urine to increase.

The urine based ovulation predictor test

Urine based ovulation predictor kit


All urine based ovulation prediction tests rely on the measurement of LH in the urine. when a high level of LH is present it causes an indicator to change colors. For most test kits, a “control” indicator is usually given to compare the change in color. Release of the egg (ovulation) usually occurs 12 to 24 hours after the test turns positive.

Advantages of the urine based ovulation predictor test

If the ovulation predictor test starts out negative and then turns positive, it is the most accurate indicator of impending ovulation.


There are some conditions that might cause a woman to have high enough LH levels all the time to cause the test to look positive all the time. These women would test positive no matter when they test their urine whether they are ovulating or not. These most common conditions that can give a false positive on an ovulation predictor test include polycystic ovary syndrome and menopause.

Ovulation predictor kits have a limited amount of materials for testing thus limiting the number of days that you can test. If you start testing early or ovulate late you may run out of materials before ovulation is predicted and have to purchase more.

Even when the test turns positive, you still don’t know exactly when the ovulation surge began. For example, if you test every morning, and it is negative on Monday and positive on Tuesday, when did the surge begin? Monday morning after the test? Monday night? The test can be affected by how concentrated the urine is (dehydration, using the first versus the second urine in the morning etc.)

Saliva Based Ovulation Predictor Tests


When an egg is developing in the ovary, it is contained in a small cyst called a follicle. The cells in the follicle produce a hormone called estrogen. As the egg develops, the follicle grows and produces more estrogen. The estrogen is secreted into the blood. As estrogen levels in the blood rise, it causes the accumulation of increased levels of a salt called sodium chloride in the saliva. When the saliva of a woman with high estrogen dries, the salt leaves a crystal pattern called ferning – it actually looks like a fern plant – that can be seen under a microscope.

The test

Saliva Ovulation Predictor Test

Saliva testers work by having women smear some saliva on a glass slide each day and observe it through a hand held microscope. In a woman who normally develops eggs each month, the slides should develop ferning as the estrogen levels rise and get close to the time when ovulation should occur.



Easy to use. No messing with urine. The development of ferns is a gradual process which allows a woman some advanced warning that ovulation may be getting close.


Saliva testers don’t actually predict ovulation at all. They only demonstrate that the estrogen levels have increased and the woman may therefore be close to the time of ovulation. The actual triggering of ovulation may occur anywhere from 24-72 hours later and doesn’t necessarily occur at all. Anything that increases the estrogen levels such as cysts, hormones, and fertility medications may cause ferning when ovulation is not imminent.

Which ovulation predictor tests do we recommend, if any?

First, I should say that there isn’t any data that ovulation prediction kits actually help couples achieve pregnancy more easily than having periodic intercourse. I know that sounds unbelievable but its true. If you have menstrual cycles that last 26-35 days and you have intercourse every other day from day 13 through day 21. You will be just as likely to get pregnant as you would with an ovulation predictor kit.

  • If your cycles are very long or irregular, there is a good chance you are not ovulating and using kits are not likely to help you.
  • If you are unsure whether you are ovulating, using a kit once or twice to confirm ovulation is a reasonable idea.
  • Also, if you are trying to get pregnant with a method that requires very accurate timing of sperm placement in the uterus such as an intrauterine insemination, then use of a urinary ovulation kit can be very helpful.
  • If your cycles are generally regular, user the least expensive urinary kit you can find.
  • If your cycles are irregular or long, the saliva tester is probably a better value since you can test for 40-50 days on a single kit
  • Combination urinary kits, such as Clearplan Easy, add nothing to the chances for achieving pregnancy and are dramatically more expensive. Avoid them!!!!
  • You do not have to have intercourse on the day of ovulation in order to achieve pregnancy. Studies show that intercourse 6 days before ovulation can produce pregnancy. In general, the closer intercourse is to the time of ovulation, the higher the chance. However, there is essentially no difference in pregnancy rate if you have intercourse two days or one day before ovulation or on the day of ovulation. Therefore, if you have intercourse every other day or every third day around the time of ovulation, you will maximize your chances. Ovulation kits, therefore, are a waste of money for most couples.