How to Track Ovulation: Do Smart Rings Actually Work?

Dr Buddhini Dolapihilla, Medical Doctor & Researcher

Are you trying to track ovulation and finding it hard?
Understanding how to track your ovulation can help you pinpoint your fertile window and time intercourse around it. You can also increase your chances of finally getting pregnant. But with smart rings and fertility trackers becoming increasingly popular, how accurate are they, and which methods can you actually rely on?

Ovulation is when an ovary releases an egg. It usually happens around 10–16 days before your next period, rather than on a fixed day of your menstrual cycle. This is why simply counting backwards from a 28-day cycle may not accurately predict ovulation for everyone.

The good news is that there are several ways to track your cycle and recognise when you are approaching your fertile window.

Know your cycle

Keeping a record of when your period starts and how long your cycles usually last can help you understand your personal pattern.

However, calendar tracking on its own cannot necessarily tell you exactly when you will ovulate because even women with apparently regular cycles can experience variation from month to month.

So in addition to learning your cycle patterns, having sex regularly—every 2 to 3 days, can help ensure that sperm are present around the time ovulation occurs.

Check your cervical mucus

Your vaginal discharge naturally changes throughout your menstrual cycle.

Around ovulation, cervical mucus often becomes clearer, thinner and more stretchy, sometimes resembling raw egg white. This change occurs because oestrogen rises as the body approaches ovulation.

Learning to recognise these changes keeps you informed about your fertile window.

Try an ovulation test

Urinary ovulation predictor kits (OPKs) detect a rise in luteinising hormone (LH) in urine.

The LH surge generally occurs shortly before ovulation, making these tests particularly useful when you're trying to identify the days when conception is most likely.

What about basal body temperature?

Basal body temperature (BBT) tends to rise slightly after ovulation because progesterone affects body temperature.

However, there is an important distinction between detecting a temperature change after ovulation and predicting ovulation before it happens.

Current NICE guidance on fertility problems advises against relying solely on basal body temperature charts to confirm ovulation, because they are not sufficiently reliable for this purpose. So, while temperature tracking can help you understand patterns in your cycle, it should not be treated as a definitive fertility test.

Do wearable devices actually work for ovulation tracking?

Fitness bands, fertility bracelets, armbands, ear-worn sensors, vaginal temperature sensors, and smart rings have made continuous temperature monitoring very convenient.

Instead of manually taking your temperature every morning, these devices can continuously measure physiological signals during sleep, including skin temperature. Some also incorporate heart rate and other measurements into algorithms designed to identify menstrual-cycle patterns.

Research is promising, but there are important limitations.

A recent study on wearable digital technologies reported a pooled accuracy of 88% for fertility-window detection, although performance varied considerably between devices and studies, although sensitivity and specificity varied considerably between technologies and studies. The researchers concluded that wearables show promise but should still be interpreted cautiously.

This distinction matters: a smart ring can provide useful information about physiological changes associated with ovulation, but it does not directly measure the release of an egg.

In other words, smart rings are best viewed as a cycle-tracking tool, rather than a replacement for established fertility methods or professional medical assessment.

What about nutrition?

Ovulation and fertility are influenced by many factors, including overall health, age, weight, hormonal health and nutrition.

A balanced diet that provides adequate vitamins, minerals, protein, healthy fats and fibre supports overall reproductive and general health. If you're trying to conceive, it is also worth discussing supplements with a healthcare professional, particularly where specific nutritional needs exist.

And remember: fertility is more than just finding the "perfect" day.

If you have been trying to conceive without success, or you have irregular or absent periods, speak with your doctor or another qualified healthcare professional. Fertility difficulties can have many causes, and getting appropriate advice is more useful than relying solely on tracking technology.

Here's what fertility experts recommend: Track your cycle, learn your body's signs, consider luteinising hormone testing when appropriate, and use wearable technology as an additional source of information but not as a guarantee that you can pinpoint your ovulation window.

References

1. https://www.nhs.uk/conditions/periods/fertility-in-the-menstrual-cycle/
2. https://www.nhs.uk/pregnancy/trying-for-a-baby/trying-to-get-pregnant/
3. Uchida Y, Izumizaki M. The use of wearable devices for predicting biphasic basal body temperature to estimate the date of ovulation in women. J Therm Biol. 2022 Aug;108:103290. doi: 10.1016/j.jtherbio.2022.103290. Epub 2022 Jun 28. PMID: 36031211. DOI: 10.1016/j.jtherbio.2022.103290
4. Shi Y, Wang CC, Yang Y, Li Q, Chung PW, Wang Y. The diagnostic accuracy of wearable digital technology in detecting fertility window and menstrual cycles: a systematic review and Bayesian network meta-analysis. NPJ Digit Med. 2026 Jan 24;9(1):139. doi: 10.1038/s41746-025-02320-8. PMID: 41580499; PMCID: PMC12886881.DOI: 10.1038/s41746-025-02320-8
5. Marshall, Nicole E et al. “The importance of nutrition in pregnancy and lactation: lifelong consequences.” American journal of obstetrics and gynecology vol. 226,5 (2022): 607-632. doi:10.1016/j.ajog.2021.12.035PMID: 34968458