Ovulation tests: what they tell you and what they don't

Ovulation tests: what they tell you and what they don't

Ovulation tests, the strips sold in pharmacies, are often among the first things people buy when planning a baby. They can be useful, as long as you know what they really measure. Here's what to know so you can use them, or choose not to, with your eyes open.

What they really measure

An ovulation test detects a rise in luteinising hormone (LH) in your urine. According to MedlinePlus, the health information site of the US National Library of Medicine, a positive result means you should ovulate within the next 24 to 36 hours, but this may not be the case for all women.

In other words: the test measures a hormone, not ovulation itself. A positive result points to likely ovulation, not certain ovulation.

How to use them

MedlinePlus gives these pointers:

• start testing 3 to 5 days before the date you expect to ovulate;
• don't drink large amounts of fluid just before testing;
• test every day: if you skip a day, you may miss the surge.

To work out when to start, the NHS notes that in most women ovulation happens 10 to 16 days before the next period. Follow the instructions that come with your test too.

Their limits

• Irregular cycles: MedlinePlus notes that you may not be able to detect a surge if your cycle is irregular.
• Some medicines: oestrogens, progesterone and testosterone can lower LH, and clomiphene citrate can raise it.
• False positives: rare, but possible.
• Not proof: an LH surge doesn't guarantee that ovulation will follow.

What about PMOS?

You sometimes read that these tests are less reliable if you have PMOS (the new name for PCOS). This isn't confirmed by the 2023 international guideline on the condition: take it as a possibility, not a certainty. Two things, however, are established:

• with irregular cycles, the surge can go undetected (MedlinePlus);
• the 2023 guideline points out that ovulation problems can occur even with regular cycles, and that if needed, a blood test (progesterone level) can check this.

If you have PMOS, talk to your doctor before relying on these tests.

What the evidence says

In 2023, a Cochrane review (Cochrane is the international network that pools clinical trials) assessed urine ovulation tests in couples trying to conceive. Here are its conclusions, with their level of certainty:

• Live births: probably improved. Moderate certainty, based on a single trial of 844 women: if 16% of women have a baby without testing, it would be between 16% and 28% with testing.
• Pregnancies (clinical or positive test): probably improved too. Moderate certainty (4 trials, 2,202 women): from 18% without testing to between 20% and 28% with.
• Clinical pregnancies alone: uncertain effect, low certainty.
• Stress: uncertain effect, very low certainty.

These results concern women under 40 who had been trying for less than 12 months. The authors stress that many of the studies were funded by the test manufacturers, so the results should be read with caution. There's also a lack of data on side effects and quality of life.

To use them, or not

Nothing says you have to use these tests. Some women find them helpful, others experience them as one more monthly pressure. If the strips become a source of stress, you can do without them: the NHS simply talks about having sex every 2 to 3 days.

If you do use them, noting your results cycle after cycle can help you see things more clearly, and it's useful to show your doctor or midwife.

When to see someone

• If you've been trying for 12 months without getting pregnant, or for 6 months if you're over 35.
• Sooner if your cycles are irregular or absent, or if you have PMOS or endometriosis: the Assurance Maladie (France's national health insurance) lists these among the situations where it's better not to wait.
• If your tests are never positive over several cycles and this worries you: that's a good reason to bring it up.

This article is for information only. Lovae is not a medical device and does not replace medical advice. For any question, ask your doctor, gynaecologist or midwife.

Sources

• MedlinePlus · Ovulation home test
• NHS · Periods and fertility in the menstrual cycle
• Cochrane · Timed intercourse for couples trying to conceive (Gibbons et al., 2023)
• Human Reproduction · Recommendations from the 2023 International Evidence-based Guideline for the Assessment and Management of Polycystic Ovary Syndrome (Teede et al.)
• NHS · Trying to get pregnant
• Ameli · Medical fertility assessment (in French)

Official sources, accessed in September 2026.