Natural Cycles, the first app to be cleared by US regulators for use as a contraceptive, has criticised the approval of a new birth control service from period tracker app Clue.
Natural Cycles knocked Clue's product for relying purely on period dates and also said its approval process had not been as thorough.
But Clue said the regulator had determined its digital Birth Control service was "safe and effective".
It is due to launch in the US in 2021.
