Intimate data, including when people have had sex, is being shared with Facebook, a study from Privacy International has suggested.

Axar.az reports citing BBC that PI studied a range of period-tracking apps to see exactly what information was shared with the social network.

It included details such as what contraception was used when periods were due and the type of symptoms experienced.

Since the investigation, one app said it was changing its privacy policies.

"Our users are made aware of our Terms and Conditions and Privacy Policy prior to signing up on Maya. Post sign up, our users can export their data and delete their account whenever they choose to."