Scientific studies over the past two decades have shown that home urine luteinizing hormone (LH) tests are highly reliable indicators of ovulation. A landmark study from 1990 published in the Medical Journal of Australia compared the results of urine LH tests with daily LH measurements taken from the blood. The urine LH test was found to be more accurate than both cervical scoring and basal body temperature (BBT) at predicting ovulation.
Another study six years later in Obstetrics and Gynecology compared urine LH tests with the gold standard for determining ovulation, transvaginal ultrasound. The urine LH tests reliably predicted ovulation within 48 hours of the egg being released from the ovary, as seen on ultrasound.
A further study in 1999 in Fertility and Sterility compared urine LH tests, cervical mucus and salivary ferning with transvaginal ultrasound. Self-assessment of cervical mucus correlated less than 50 percent of the time with ovulation, while salivary ferning correlated less than 40 percent. By comparison, the urine LH tests correlated 100 percent with ovulation as seen by ultrasound.
Similar to pregnancy tests in design, urine LH tests work by wicking urine up a test strip to the testing areas. One line shows that the test is working correctly, and another line shows whether LH is present. When the second line is as dark as or darker than the control line, a woman's LH surge has arrived, and she will be ovulating within the next day. Having unprotected intercourse during the next 48 hours can maximize her chances of becoming pregnant.
All of this leads to a question: Which is the best urine LH test to use? The most tested and recommended in scientific studies is the Clearblue Digital Ovulation Test (Est. $36 for 20) , making it the best urine test strip in this report. The urine LH test used in the Medical Journal of Australia study mentioned previously was the Clearblue Easy Ovulation Test (now called the Clearblue Digital Ovulation Test). A study in 2001 published in Obstetrics and Gynecology compared basal body temperature (BBT) with the Clearblue Easy Ovulation Test using transvaginal ultrasound to verify ovulation. In 100 percent of the cases, the LH peak as detected by the Clearblue test occurred within the three days prior to ovulation, whereas BBT was a poor indicator of ovulation.
However, the Clearblue Digital Ovulation Test isn't the only LH urine test that can accurately indicate ovulation. While many expert reviews include the Clearblue Digital Ovulation Test specifically (and several are paid for by the makers of Clearblue), they also generally conclude that urine LH testing, in general, is an excellent way to monitor ovulation. For a less-expensive option, Wondfo One Step Ovulation Urine Test Strips (Est. $20 for 50) use the same testing method and provide results that are parallel in accuracy to Clearblue.
When it comes to usability, though, Clearblue Digital Ovulation Tests have the advantage. One consumer test cited often in major scientific reviews compared various urine LH tests on their sensitivity to LH. The Clearblue Digital Ovulation Test was determined not only to be the most sensitive, but also the easiest to read. At Amazon.com and Drugstore.com, many owners rave about it, saying it helped them conceive in just a month. With this test, you use the test strip like a standard urine test, but once it's inserted into the digital test holder a clear smiley face (for LH surge) or empty circle (for no surge) appears, which many users like. On the other hand, the basic Wondfo test strips can provide degrees of positive results, so that those with lower LH spikes can still see the days that are relatively high compared to other days.
Both have their disadvantages, though. While the Clearblue Digital Ovulation Test holder is a nice feature, some owners report that it can malfunction, giving only error readings. And according to many new users, the Wondfo strip results are a bit more difficult to interpret -- "Does that line mean it's really positive?"
There is a third well-reviewed testing option which offers users a few more days of warning before ovulating. Clearblue Advanced Digital Ovulation Test (Est. $40 for 20) works like the Clearblue Digital Ovulation Test, but the test strips also monitor estrogen. A spike in estrogen occurs about two to four days prior to the LH spike, indicating a total of up to six days with a high chance of conception. From a usability perspective, the Advanced Ovulation Test is almost exactly like the Digital Ovulation Test, with users reporting the same concerns over malfunctioning test holder sticks.
For those who may be trying to conceive for many months, price will likely be a deciding factor. These three products range from $20 for 50 tests to $40 for 20 tests -- quite the difference. The Wondfo test strips are our pick for best cheap test strip because they're well-reviewed amongst users and they're more economical for those with longer or more irregular cycles who will have to do more testing. A few Amazon.com reviewers say they feel a bit cheated by the Clearblue Digital Ovulation Tests, because replacement test strips are hard to find, so they end up needing to repurchase the entire digital test holder and test strip bundle each month.
Finally, some women cannot use urine LH tests. If a woman is on fertility medications, has polycystic ovarian syndrome (PCOS), is already pregnant or is in menopause, she can get false positive results. In addition, any health conditions, such as thyroid disorders or medications that affect her hormones can alter the test results. Of note, Clomid, also known as clomiphene citrate, may interfere with the test. If a woman is using this medication, she should consult with her doctor before trying a urine test.
While the Clearblue Digital Ovulation Test is a well-reviewed and promising urine LH test, Clearblue continues to lead the way for best ovulation predictor with the Clearblue Fertility Monitor (*Est. $170) ; replacement test strips cost about $38 for 30. Urine luteinizing hormone (LH) tests predict the two most fertile days for a woman each cycle, but the Clearblue Fertility Monitor can predict up to six fertile days. The difference is that the Clearblue Monitor tests not only for LH, but also for estrone-3-glucuronide (E3G). For the first month, a woman tests for 20 days to create a baseline for her cycle. The battery-operated monitor then tells her when to test over the next month, often 10 to 20 days, and informs her if she's at low, high or peak fertility.
Multiple scientific studies have demonstrated the reliability and effectiveness of the Clearblue Fertility Monitor. A study published in 2000 in Human Reproduction compared its reliability with transvaginal ultrasound. Researchers found that during the two peak fertility days listed by the monitor, ovulation, as seen by ultrasound, occurred 91.1 percent of the time and peak fertility was never indicated after ovulation had occurred.
A further study of the monitor's efficacy, published in Fertility and Sterility in 2007, tested the monitor's ability to help couples conceive. More than 300 women were provided with the Clearblue Fertility Monitor, while another 300 women were not and acted as a control group. The testers weren't given any directions besides the manufacturer's instructions. The couples that used the monitor had a pregnancy rate of 22.7 percent during the first two menstrual cycles, while the control group's pregnancy rate was only 14.4 percent, showing that monitor usage increased couples' chances of getting pregnant.
Beyond the scientific and medical community, the Clearblue Fertility Monitor is one of the most popular fertility devices. Consumer testing found it to be one of the most sensitive tests to LH, second only to the Clearblue Digital Ovulation Test. JustMommies.com chose it as one of the best fertility gadgets, and About.com's pregnancy guide, Robin Elise Weiss, gives it 4.5 out of a possible 5 stars. Though Weiss finds the Clearblue Monitor accurate and easy to use, she notes that the greatest drawback is the high price for the monitor and test strips.
The Clearblue Fertility Monitor costs $170, with test strips running about $38 for 30, plus the cost of four AA batteries. In comparison, the Clearblue Digital Ovulation Test strips run about $21 for seven strips, though they can be difficult to find. Numerous reviewers at Amazon.com, Drugstore.com and Diapers.com, however, say that the Clearblue Fertility Monitor is well worth the price. They find it easy to use and easy to read, and many say they conceived within the first few cycles of use.
Like urine LH tests, the Clearblue Fertility Monitor has its weak spots. Those with an irregular menstrual cycle may have to use closer to 20 test sticks each month, effectively doubling your cost. If your menstrual cycle is less than 21 days or more than 42 days, this monitor won't work for you. Polycystic ovarian syndrome (PCOS), impaired liver or kidney function, pregnancy and menopause can alter the results. In addition, fertility medications and any health conditions or medications that affect your hormones can also affect your test results. As always, if you have any health conditions or are on any medications, consult with your physician before using this or any other fertility device.