How do they work?

Ovulation Predictor Kits (OPKs) provide a positive test for Luteinizing Hormone (LH) using a urine test strip. Ovulation Prediction Monitors (OPMs) usually allow multiple ovulation predictor urine strip results to be combined to provide a monitoring picture of Luteinizing Hormone (LH) over a cycle. Some monitors use a urine strip that combines LH with E3G - a metabolite that allows assessment of the estradiol level.

How close will the results be compared to OvuSense?

Firstly, OPKs and OPMs are only able to provide a prediction of when ovulation may occur during the current cycle. They are not able to confirm you have ovulated, and because of the lack of confirmation they cannot be used to reliably predict your fertile window for the next cycle. When you're using the OvuCore Sensor your OvuSense App will also provide you with a prediction of when you are about to ovulate using the current cycle data. As this is based on the temperature pattern caused by the release of progesterone associated with ovulation, rather than luteizing hormone, it may well provide you with a different prediction. This is particularly true if you have an ovulatory issue such as PCOS which is known to interfere with OPK and OPM results. However, if your OvuSense App and an OPK or OPM predict the same day for ovulation then this can be very useful in confirming your hormone behaviour throughout the cycle.

What are the benefits?

LH peaks up to a day in advance of ovulation so OPKs and OPMs are helpful in providing a short term indication of when you should try and conceive based on your current cycle data. They work well at predicting ovulation for most women that have regular 'middle of the month' ovulation. The addition of E3G with OPMs helps provide a fertile window prediction and storing multiple results in the monitor helps with the convenience and monitoring over time compared with OPKs.

What are the drawbacks?

OPKs are known to give false positive results for women with PCOS and other ovulatory issues [1]. They sometimes also give false negative results, which can be based on the cutoff point of the test, or simply that the test is not optimised for the natural level of LH for the particular user. OPKs can only provide a snapshot at one point in time in your cycle, meaning you have to use a minimum of two tests a day over a 10-20 range in each cycle to monitor where you are in your cycle. The manufacturers make valid claims for 99% accuracy in detecting LH, but the accuracy estimates for correct advance prediction of ovulation are 70%-84% depending on the publication [2]. OPKs and OPMs are unable to confirm the date of ovulation or if you haven't ovulated. They are sometimes thought to be messy, impractical and the cost quickly adds up. Lastly, they cannot be used for clinical monitoring as they only provide a picture up to the point of ovulation and no understanding of what happens during ovulation itself, and the luteal phase.

[1] McGovern PG, Myers ER (2004)
[2] Irons DW, Singh M (1994); Lloyd R, Coulman CB (1989);