ovulation prediction

Ovulation Predictor Kit Frequently Asked Questions

BFP ovulation predictor kit

Ovulation predictor kits can be purchased online here. Pricing ranges from $.80/test to $.55/test based on the number of tests you purchase, and shipping is free.

Q: What is an ovulation predictor kit (OPK)? What does it tell me?

A: An OPK is a test that looks for luteinizing hormone (LH). Just prior to ovulation, women experience a short surge where the LH level rises to a higher level. The OPK will help you pinpoint this surge and help you predict when you will ovulate.

Q: Which OPK is best?

A: It seems that ClearBlue Easy is probably the easiest to find, and that ClearBlue and OvuQuick are the ones most discussed on the newsgroups. Many people post that their reproductive endocrinologists recommend ClearBlue or OvuQuick. For more information on OPKs you can check the Consumer Reports. You may want to try a couple of different tests and see which one works best for you.

There are between 5 and 9 tests per kit, and the average cost is $3-$7 per test. Expect to pay $15-$70 per month. They are not refillable.

As noted previously, reliable ovulation tests can also be purchased online at a significant discount.

Q: What time of day should I test?

A: The best time to test is 2 p.m., or as close as possible. Anytime between noon and 8 p.m. is fine, first morning urine is not recommended. The reason for this is that most women experience a surge in the morning, but it can take 4 hours for it to show up in your urine.

Make sure to test at about the same time every day.

Q: On what day of my cycle should I start testing?

A: If you have a variable cycle, you should use the date of your shortest cycle in the past six months as a starting time.

Cycle Length Start Day
21 5
22 5
23 6
24 7
25 8
26 9
27 10
28 11
29 12
30 13
31 14
32 15
33 16
34 17
35 18
36 19
37 20
38 21
39 22
40 23
41 24
42 25

Q: I have a long cycle, how many days will I have to test?

A: It varies. The best thing to do is figure out the length of your shortest cycle in the past six months, and begin testing on the day mentioned in the chart above. Continuing testing until you detect a surge or have a sustained temperature rise (at least 4 days, and at 0.4 degrees higher than the previous six temps.).

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 need. Example: Your shortest cycle is 28 days and the longest is 42, you would begin testing on day 11, but may need to continue through 20 tests, or even more. Note that this isn't common, but it is possible. About 90% of women will detect a surge within 10 days of testing.

Try not to lose patience and keep on testing . . . you'll learn more about your cycle then if you stop.

Q: Does Clomid cause problems with OPKs?

A: Clomid (Serophene/clomiphene citrate) can cause a false positive in OPKs if taken too soon after finishing the prescription. According to most of the manufacturers you should wait at least 3 days before using an OPK. If you take Clomid days 3-7 you can begin testing on day 10. If you take it 5-9, you should wait until day 12.

Q: Can I use OPKs if I am taking injectable fertility drugs such as Pergonal, Humegon, Repronex, Gonal-F, Follistim, or Fertinex?

A: This is a tough one to answer. Pergonal, Humegon and Repronex are made from LH+FSH and may contain enough LH to cause a false reading, though the FSH-only meds, Gonal-F, Follistim and Fertinex, should not effect testing.

With any of these drugs, patients should have follicle size monitored by ultrasound and then get an HCG trigger to induce ovulation when the follicles are large enough rather than relying on OPKs. Many patients do not have a natural LH surge while on injectable medications. Some doctors will ask you to use OPKs in addition to ultrasound monitoring, but be weary of one who goes only by OPKs.

Q: What if the OPK uses pee-on sticks and I'd rather use a cup?

A: Take a sterile cup, fill it with urine, and dip the stick in for between 5 and 20 seconds. If you need to store the urine for any length of time before testing, consult the package insert to see what your OPK suggests.

Q: How long after my LH surge should I ovulate?

A: Most people will ovulate 12-48 hours after the LH surge is detected, most common is 36 hours after the actual surge. One should get a bit more notice, 24-48 hours, by testing in the afternoon.

Q: Once I detect my LH surge, when should I have intercourse?

A: It's best to have intercourse the day of the LH surge and the two days after. Also consider "insurance" sex for one more day in case you ovulate late. Perfect timing would be to have had intercourse the day before the LH surge as well, but that can be hard to predict for those with an irregular cycle. If you don't know when you might ovulate, having sex every other day from cycle day 10 through a positive OPK. If you are taking your basal body temperature, you should have sex through the first day of your temp rise to make sure you cover all days (though after the rise is usually too late).

Q: How long after my LH surge should I have my insemination?

A: Most doctors will do an intra-uterine insemination (IUI) the day after the LH surge, or about 36 hours after it is detected. With a vaginal insemination, or an intra-cervical insemination (ICI) in someone with good fertile mucus, the day of the surge may be preferable. Many doctors are now doing two inseminations per cycle. Check the IUI FAQ.

Q: If I see any line in the result window, is that a positive?

A: Unlike home pregnancy tests where a line in the result window indicates a positive, OPKs are only positive if the test result line in the same color or darker than the reference line. Refer to the instructions in your test kit to be sure you know which window is which, and whether the line has to be as dark (Clearplan) or darker (OvuQuick).

(Clearplan) or darker (OvuQuick).
Test Same Color Positive Some Brands
Test Same Color
Positive Some Brands
Test Darker Positive All Brands
Test Darker
Positive All Brands

Q: How come I always have a faint line in the test result window? Does this indicate a problem?

A: We always have LH in our systems, so the test can pick it up. Most of the tests don't show a full positive result until 25-40 mIU, but many will show a faint line with LH levels over 10 mIU. If your result line often has significant color, you should consider trying another brand. If you still get a significant line, you should consider having your doctor test your LH levels on the third day of your next cycle to see if your hormone levels are elevated. FSH levels should be checked at the same time as LH, especially if PCOS is suspected.

Faint Line Normal ResultFaint Line
Normal Result
50% Color Concern if Daily
50% Color
Concern if Daily

Q: What does it mean if my test line gets darker for a day or more before the actual positive?

A: Some women have a fade-in pattern where the test will get darker for a day or two before the positive result. This generally isn't anything to worry about, and may have the benefit of a bit of advanced noticed. If you find you have a fade-in pattern, you should begin having intercourse when the fade-in pattern starts.

35% Color 35% Color
65% Color
65% Color

Q: I have PCOS. Can I still use OPKs?

A: It depends on whether one of your PCOS (polycystic ovary syndrome) symptoms is elevated LH. You can get some false positives or misleading results. A PCOS patient may have more success tracking ovulation via ultrasound. The only way to know if it is reliable for you is to try it.

Q: I had a positive LH surge, but tested again the following day anyway. It was positive again! What does that mean?

A: This isn't a problem. You may have caught your surge on its way up and on the way down. It is more common to only get one day of positive testing, but it is not uncommon to have two days of a positive tests. Even three days isn't uncommon, but it is worth consulting a doctor in case you have high LH levels.

Q: If I'm taking my basal body temperature, what's the point in doing expensive OPKs?

A: The OPK will tell you when to expect ovulate before it happens, while BBT only tells you after it's over. The thermal shift occurs *after* ovulation in response to increased progesterone production. One your temperature goes up, it's too late to get pregnant. By using OPKs, you'll know before ovulation and can be sure to get your timing right.

Q: If I am doing OPKs, why should I still bother to take my BBTs?

A: There are a couple of reasons why it would be a good idea. The first is so that you can see if your LH surge corresponds properly with your thermal shift. You should shift 1-3 days after your positive OPK, though sometimes it takes as long as five days for those with a slow shift.

Another reason is to make sure your temperatures stay up for at least 10 days after ovulation. Your falling BBT will let you know when your period is starting, but if your temperature stays elevated 18 days past ovulation you should test for pregnancy.

Q: What if I don't detect a surge, but I have a thermal shift?

A: You probably missed your surge. Some people need to test more than once per day. If you've had a test that was half-color and then negative the next day, plus a thermal shift, in your next cycle you should consider testing twice a day (noon and 8 p.m. would be a good choice).

Another possibility is that you didn't hold your urine long enough. Several tests suggest holding urine for 4 hours before checking for LH.

Q: I used an OPK, my timing was perfect, why didn't I get pregnant?

A: It often takes a number of perfectly timed cycles before pregnancy is achieved. The chances of getting pregnant each cycle varies a bit with age. If you are 20-25, your chance per cycle are about 25%. From there they begin to fall off. At 25-30 your chances are about 20%. At 30-35 they are about 15%. After 35 they may be about 10% per ovulatory cycle, and the chances continue the downward trend.

This means that the average woman under 30 will get pregnant within 6 cycles. If you don't succeed after a year, it is a good idea to consult a fertility specialist. Women in their early 30s get pregnant on average by the end of 9 cycles. Mid-30s would be a year. If you are over 35, you should consult a fertility specialist if you have not achieved pregnancy within 6 months. Why 6 months when it can take a year? Because your chances of conception are lower and miscarriage rates are higher -- it is better not to waste time.

Q: What about those re-useable microscope fertility indicators?

A: The fertility microscopes are used to detect a ferning pattern in either your saliva or your fertile mucus. Many women have success with these testa, while others find them hard to interpret. These tests are not as exact as detecting your LH surge -- the fertile window often ends up being about 6 days. Some women with high estrogen levels (many overweight women) will find they appear fertile more often than they actually are.

Q: Are expensive fertility monitors more accurate than OPKs?

A: The monitors, such as the ClearBlue monitor, test estrogen and LH. They tell you when you are not fertile, fertile, and then peak fertility. Like OPKs, they may not be as reliable in women with PCOS, and there cost may be prohibitive to those just starting out. The Clearplan monitor usually can be found for about $180 with 20 test sticks. Replacement test strips cost a bit over $1 each. One option that doesn't require test sticks is the OvaCue Wireless Fertility Monitor. This fertility tracker uses the Electrolyte Method, it's suitable for women with PCOS, and it doesn't require urine-based testing.

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