Electric blankets on the lap, and sitting on heated car seats, can have a similar effect to hot baths, which may make it more difficult for men to get their partners pregnant, some UK experts have said.
Doctors are urging men to turn off their car's heated seats if they want to stay fertile, for fear that the popular feature could increase the temperature of the testes, adversely impacting sperm production. Heated seats are becoming increasingly common in vehicles around the world, and are particularly popular at this time of year, with temperatures dipping below zero.
Everyone inherits two copies of a gene called factor V (F5) from their parents. However, eight per cent of people have a mutated version that triggers a disorder called Factor V Leiden.