Apps which track a woman's fertility cycle have become increasingly popular in New Zealand, but experts here are warning to treat them with caution.
One fertility app user, Kayleigh Inglis uses an app to track her periods, saying it's highly accurate.
"I also use it to chuck in information about 'am I bloated?', 'how are my moods?', 'do I have a temperature that day?' It's just basically like a little diary you're keeping to yourself," Ms Inglis said.
Fertility Associates expert Dr Andrew Murray says it "would be pretty unusual for a woman not to pull out her phone and have tracked her cycles".
"Fertility apps in general are good for raising awareness about a woman's fertility, but they do make a lot of assumptions," Dr Murray said.
It comes after British woman Rebecca Woodhead claims she became pregnant while using 'Natural Cycles', a Swedish app being advertised as "99 per cent accurate" and a "natural" alternative to contraceptives.
The Advertising Standards Authority in the UK has since banned the company from labelling the app "highly accurate", saying that the claims were misleading.
"A year or so ago, when I saw it on Instagram, I was led to believe it was 99 per cent effective," Ms Woodhead said.
The apps are a modern day take on the old-fashioned contraceptive rhythm method of tracking a woman's fertility cycle, and critics say they should not be used as a contraceptive.
"Let's not forget that the reason they exist is primarily not just to help women understand their fertility, it’s also to sell advertising and promote other products around that," Dr Murray said.