A woman from Milton Keynes has been arrested at Heathrow Airport on suspicion of conspiracy to commit child cruelty by Female Genital Mutilation.
The 33-year-old woman was travelling with a girl aged 11, who was taken into police protection.
A 26-year-old man from London was arrested at the same time.
The arrests were part of Operation Limelight, a police initiative launched to clamp down on the illegal practice.
Officers targeted flights returning from countries associated with FGM, such as Abuja, Sierra Leone and Lagos, and intercepted families as they arrived at the airport.