I’m A-. I’m married to a A+ guy. I’ve had 5 A+ kids and two miscarriages. I received rhogam shots at about 28 weeks and after birth for the kids, and shots after the miscarriages.
Perhaps she had a miscarriage and wasn’t treated, or perhaps there is some transfer. Good luck.
When I think that even 40 years ago, I would have been lucky for my first child to survive, and my subsequent ones would probably have been doomed, I realize how fortunate I am.