Clearblue Easy, the pregnancy and fertility products company, is 50% owned by Procter & Gamble and 50% owned by Geneva-based company Swiss Precision Diagnostics.
Leo Burnett won the account after a pitch that included its Publicis Groupe sibling Saatchi & Saatchi.
The business had previously been handled by Amalgamated New York. It produced work including a TV ad for the digital pregnancy test, which launched last year with a voiceover that said: "Introducing the most sophisticated piece of technology… you will ever pee on".
A spokesperson for Procter & Gamble, said: "Leo is a great fit for the brand with tremendous understanding of the global female consumer. They are a global agency, which was important as the scope of the assignment is multiregional.
"Importantly they presented a compelling solution to take the product from medical device to one that also delivers emotional benefit."
It is unclear whether Leo Burnett will handle other products launched by Swiss Precision Diagnostics.
Clearblue Easy was previously owned by Unilever until it sold the brand to Inverness for $200m in 2001. Procter & Gamble paid $325m for only half the business last year.