Software king of the world Sir William Gates and his wife Melinda are taking on their biggest enemy since the mosquito – the Roman Catholic Church.
Melinda Gates, who is a Catholic, has said that the Gates Foundation will dedicate the rest of their lives improving access to contraception across the globe.
Gates told the Sydney Morning Herald that unless the Church pulled its finger out on contraception, women in African and Asia would be "voting with their feet", as women in the West had done, and would ignore the church ban on artificial birth control.
She said that she had been inundated with messages of support from Catholic women, including nuns who wanted the Church to be more sensible about contraception. There were women out there who had been coming on to websites and saying 'I'm a Catholic, but I believe in contraception'.
She said that in the West, while Bishops banged on about contraception, ordinary Catholics just did the opposite. In Africa however it was a big trickier.
In the US, 82 per cent of Catholics say contraception is morally acceptable. So let the women in Africa decide.
Melinda said that she did have some problems speaking out in defiance of the church hierarchy.
As a Catholic she believed in the religion and its "amazing moral teachings". But she also had to think about keeping women alive.
When it comes to not letting women or babies die, that's more important than arguing about what method of contraception is right, she thinks.
Mr and Mrs Gates are pouring $560 million into improving access to birth control over the next eight years.
She said it was time to push contraception back to the top of the development agenda.
She said that when the Gates Foundation started, it had focused on family planning. However it changed direction to vaccines after realising that women would not choose to have fewer children until they were sure their offspring would survive beyond childhood.