Couples desperately trying for a baby could be about to get a helping hand from a new gizmo which reveals when a woman is at her most fertile. The Fitbit-style wristband is able to tell when a woman is about to ovulate by detecting tiny changes, such as her temperature and resting heart rate.

Its makers say it is 90 per cent accurate. And, while there may have been an embarrassment issue if women had to wear it during the day, it actually works while she sleeps. A woman wears the device overnight before taking off the wristband and then sending the information it has collected to her smartphone.

However, the gizmo does not come cheap. It is due to be launched in the UK this week at a price point of £199. However, its manufacturers say that it is a real alternative to the current urine test method which woman currently use to determine when they are fertile.

Changes in the body

It’s inventors say that while it looks like a watch, it tells when the best time is to have sex in order to make a baby, rather than telling the time. It monitors skin temperature and resting heart rate because both of these increase as a woman’s body prepares to ovulate.

Before the gadget was brought to market, it was subject to a year long study which took place in Switzerland. This research project, which involved 41 women, found that it was 89 per cent accurate in predicting the most fertile days in the month. The Swiss firm Ava said that its new piece of tech could help to make trying for a baby a less stressful and frustrating experience.

However Professor Adam Balen, who is chairman of the British Fertility Society, said he feared it could have the opposite effect by making people feel pressured into having sex at a particular time, actually adding to the stress of trying to fall pregnant.