@theredjellybean I agree, I didn't think they actually managed to have sex that time, I thought Serena tried oral sex and Fred rejected her.
But I can't work out why they're not allowed.
Surely the more opportunity to get somebody pregnant the better, and you can guarantee that the Wives would still get the blame if no pregnancy occurred.
I wondered if it's perhaps to stop the Wives getting pregnant to the doctor or the Chauffeur and passing off that baby as her husband's child.
It's one thing for everybody to pretend the Handmaid is pregnant by the Commander when they all know differently, another thing entirely to pretend that a Wife hasn't been unfaithful in order to get pregnant.