How do Ovulation Tests Work?

Ovulation Test

Ovulation test kits are one way that you can use in order to predict whether or not you are ovulating.  Ovulation is when the egg has a follicle in it containing an egg ruptures, releasing the egg that then travels down the fallopian tube awaiting fertilization.  The egg will survive 12-24 hours after ovulation.  After that, the egg degenerates and you cannot get pregnant during that cycle.  There about 6 days in your cycle in which you can get pregnant (5 days before ovulation and the day of ovulation).

Sperm can reside in the uterus and fallopian tubes about 5-7 days so you can get pregnant even if you haven’t had intercourse on the day you ovulate.  The healthiest sperm that are best able to result in a fertilized egg are those that are just released.  This is why you should have sex every other day or so during your fertile window so that you can have plenty of healthy sperm to fertilize the waiting egg.

The best chance for a pregnancy is to have sex in the two days leading up to the day of ovulation.  While you can achieve a pregnancy having intercourse earlier than that, your best chances come from recently ejaculated sperm near the day of ovulation.
how do ovulation tests work

Will an ovulation test kit actually help achieve a pregnancy?

Ovulation test kits can help you find out when you are the most fertile; however, whether or not in increases your chance of getting pregnant is controversial.  The best way to get pregnant is really the old fashioned way and that is to have intercourse on a regular basis throughout the menstrual cycle.

You may need to be more clinical about conceiving a child if you have difficulty getting pregnant because one or both partners is often away from home, you have a hectic schedule, or you have irregular menstrual cycles.

There are a couple of good ways to determine when you are most likely to conceive.  Some older ways are to simply check your cervical mucus and have sex when the mucus is clear in color and stretchy (this is referred to as favorable cervical mucus) or by checking your basal body temperature reading by determining your temperature just before getting out of bed in the morning.  The BBT method will show an increase in temperature upon ovulation.

If you want to be high tech about it, you can use an ovulation test kit.  This is a test kit that measures your LH surge, which is the time in the cycle when the pituitary gland puts out a spike in luteinizing hormone (LH) that tells the ovaries to release the egg.  If you have irregular cycles or other fertility issues, an ovulation test kit can be extremely beneficial in determining when you are most likely to get pregnant.

How do these test kits work?

how do ovulation tests work
The test kits check the urine for the LH surge.  The LH surge happens about 1-2 days prior to ovulation.  The pituitary gland puts out LH throughout the cycle but it increased 2-5 times above baseline at the time of the LH surge.  You are most likely to achieve a pregnancy if you have sex within 2-3 days prior to ovulation, which is when the ovulation test kit indicates an LH surge.

You can also use a salivary ferning kit.  You need a small microscope, microscope slides, and some saliva.  In this kit, you smear a bit of saliva on a slide, let the saliva dry, and look for a fern pattern in the dried saliva.  This is a trickier test than checking the LH surge, however.

How are ovulation test kits used?

The way you use an ovulation test kit depends a bit on the type of test kit you choose.  You may have to use a kit in which you pee into a cup or pee directly on a test stick.  You may have the “two line” test kit, in which you compare a surge line with a reference line to see if you are ovulating.  Some test kits are digital and will simply indicate with a yes or no response whether or not you are having your LH surge.

The instructions for each test kit are a bit different from one another but the basic idea is to collect urine preferably the first thing in the morning; however, as long as you do it after not voiding for 4 hours and do it the same time every day, you can check the urine anytime during the day.  The best time to do an LH surge test is between 2 o’clock pm and 2:30 pm.

Restrict fluids about two hours before testing as this yields the most concentrated urine.  After you collect the urine (or pee on a stick), you will need to wait 5-10 minutes in order to see if you are having an LH surge.  Using the “two line” test, you are looking for the surge line to be equal in intensity or higher in intensity when compared to the reference line.

If you choose to do the saliva ferning test, you simply put saliva on a microscope slide, let it dry, and then look for the fern pattern of the saliva underneath the microscope. It should be done first thing in the morning.  You can lick the slide or can put some on your finger and smear the saliva with as few air bubbles as possible onto the slide.

Either test will tell you when you are most fertile. Your most fertile day is the 17th day before you expect to get your next period.  It is measured this way because some women have longer cycles than 28 days and the last half of the cycle is the most predictable, being 14 days before the next menstrual cycle.

Tips you should Know

Acetaminophen and other commonly used drugs won’t interfere with the test.  The only drugs that may interfere with the test include anything that contains HCG in it and Clomid, which is a popular fertility drug (it only affects the fern ovulation test kit).  Urine-based testing is about 99 percent accurate in predicting your LH surge and is probably the best way to determine whether or not you are ovulating.

Remember that the kits measure the LH surge but can’t predict that the egg has actually made it to the fallopian tube.  You can also have more than one LH surge per cycle, which can greatly confuse the matter.  These false LH surges can make you think you are ovulating when you aren’t.

The fern test kit isn’t as accurate as the urine LH surge test as there can be ferning even when you aren’t ovulating and the detection of the fern pattern takes practice.

Cost of Ovulation Test Kits

The typical urine ovulation test kit runs about $30 USD per cycle.  Almost all the tests use the same method of detecting LH surging so you don’t need to use the most expensive kit to still get decent results.  There are usually 7-9 test kits per test kits.  Once the LH surge has been detected, you don’t need to continue testing and can use the remaining test sticks on your next cycle if you don’t get pregnant during this cycle.


  1. How to use ovulation predictor kits.


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