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What is OPK?

If you’re trying to identify when you ovulate each month, you may have encountered OPKs. If you haven’t, they’re something you need to know about so you can make an informed choice about how you’re monitoring your fertility, and give yourself the best chance to conceive as soon as possible.

What Does it Mean?

OPK is short for Ovulation Predictor (or Prediction) Kit. They’re a widely available product that you can buy in many pharmacies and supermarkets and they work like a home pregnancy kit, testing urine for hormones.

What do They Test For?

OPKs test for the Luteinising Hormone, known as LH. This serves an important purpose in men and women’s bodies, but for women it’s closely connected to the reproductive cycle. In the first half of the cycle, low levels of it stimulate the ovarian ‘follicles’ to ready an egg, and then roughly twoweeks after the start of your cycle the level surges suddenly, triggering your ovaries to release the egg.

OPKs test for this hormone surge around the middle of your cycle: detecting elevated levels of LH means the test gives a positive result: you are ovulating, it’s a good time to try and conceive!

Do They Work?

In brief: mostly. To go into more detail, it depends on the circumstances.

As these are an off the shelf product, they can’t be tailored specifically to your body. If you’re not the ‘average woman’ they’re designed for, or you’re not following the guidelines specifically their predictive power is diminished, sometimes to unusable levels.

This is in contrast to OvuSense, which directly measures your basal body temperature to work out your own average, and then uses dips and spikes in that temperature give you notice of when you’re due to ovulate!

Ambiguous Instructions

Even for a simple product, some of the instructions can be ambiguous and confusing, specifically when you’re meant to use them.

The directions normally indicate they’re for use around the middle of your cycle, to help you narrow down the general window when ovulation may be due. If you have a very regular cycle then they’re a good fit for you. If you don’t (and cycles can be disrupted by stress, by medical conditions and simply chance) even identifying the right window to use them in is tricky.

On top of that, there’s some debate about the best time in the day to take the test! Some authorities say first thing in the morning gives you the best chance at an accurate reading, while others claim the Luteinising Hormone surge doesn’t build up in the urine until later in the day.

With ambiguity like this, it can feel stressful to use these kits, as you can’t be sure you’re doing the right thing to get a result and may be missing out.

Beyond the Average

If you do depart from the average profile these tests are optimised for, you could experience both false positives and false negatives that make them less useful. Bodies simply differ, and if, by chance you have particularly strong or weak surges in LH you’ll find it causes the test to deliver bad results.

More complicated conditions like PCOS can disrupt your cycle and hormone balance can throw the test off entirely, meaning it’s just not the right option for you.