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Can Ovulation Tests Be Wrong?

When you’re trying to get pregnant you’ll find yourself immersed in the world of fertility tests and tracking. The key time each month is ovulation: you need to know when you ovulate so you can try to conceive at the time you can actually get pregnant.

There are plenty of ovulation tests available, and the question you need to be asking is ‘do they work?’, or, more pointedly, can they be wrong? False positives and false negatives can mean missing your chance to conceive in each menstrual cycle, trying at the wrong time, or giving you a distorted understanding of just how your cycle works.

There are two main methods ovulation tests use tell if you’re ovulating (or predict when you’re due to ovulate) – hormone testing or BBT measurement. Both have positives and negatives so let’s take a look at them and see if they can be wrong and how wrong they can be.

Hormone-Based Testing

These kits work like pregnancy tests: they test your urine for levels of important hormones and use the outcome to deliver a simple answer: yes or no. The hormone they look for is the Luteinising Hormone, known as LH. It spikes immediately before ovulation and so a build up in your urine can indicate when you’re ovulating.

Can They Be Wrong?

There are lots of ways this kind of testing can go wrong: if you have a naturally strong LH surge it can register days before and after your ovulate, making it harder for you to identify that key event. If you have PCOS, they’re even less useful as the condition is driven by a hormone imbalance and causes tests like this to regularly return false positives and negatives.

There’s also debate about the best time to use them: some people suggest first thing in the morning gives the most accurate result, whereas others advise waiting for the afternoon to capture the necessary surge LH.

If you can miss the answer by not using the test at the right time, it’s hard to be confident in the results.

Basal Body Temperature

Your basal body temperature provides a good indicator of when you’re due to ovulate, if you can capture it. This is the temperature your body drops to at rest – when you’re asleep – and over the course of your menstrual cycle it dips and rises. Learning those patterns is the key to predicting when you ovulate, but it starts to rise as soon as you wake up, and the movement necessary to simply get up and take your own temperature can swamp your body’s clear signals with noise.

Can They Be Wrong?

If you’re not able to get a close enough reading to that basal body temperature it can be hard to spot the dip in temperature that precedes ovulation, and the rise immediately after you ovulate – and some people’s patterns and cycles can differ.

With good information, however, you should be able to identify the pattern your body uses. This is the system OvuSense uses, and our sensor monitors the temperature in your vagina overnight, every night to help you get the best possible data, and interprets it to give you a notification of when you’re due to ovulate with 96% positive predictive power.

Find out more about core temperature technology and fertility here