what types from both parent be to produce O- baby?
According to this calculator, the father could be A, B, or O.
The website also strongly states that this shouldn't be used to make assumptions about family trees - that this is theoretical only.
Go to the link where it says "Blood Type and RH factor" on the left hand side.
If there is a question about paternity, a DNA test is more reliable.
If the baby's blood type is O, then the mother or the father would have to have O blood, that is the way it was explained to me.
With my daughter I had O+, Ava has A+...we do not know what her Daddy's blood type is, but the hospital explained that her Daddy could only have A, or AB in order for Ava to receive the A type.
I did not question paternity but I wanted to have Ava's blood type in her records at home. I assumed she would have my O type, I was a little bummed when they said A+.
I am sorry, I was wrong - the father could be A as well... here is an article that seems pretty detailed.
From my understanding, father would have to be O-
It's a long explanation, really. Just like blue eyes, o blood is a recessive gene. You need an o from each parent to be o blood. Like brown hair, a and b blood are dominant. If you get an o from one parent and an a from another, the baby will be a. If you get an a from one parent and a b from the other, because they are both dominant types the baby will be ab. Negative rh is also recessive, needing a - gene from each parent, while + is dominant, only needing from one parent.
If mom is a+, she can still carry a recessive gene for o-, from one of her parents. If dad is o- he can only carry 2 o- genes. The baby will get an o- gene from dad and either an a or o gene and - or + gene from mom. Baby can be either o-, o+, a+ or a-.
A baby with 2 o- parents will only be o-, but a baby with an o+ and an o- parent could be either or, if the + parent also carries the recessive - gene.
You will not be able to tell if someone is definately the parent of a child by blood types, and you may only rarely be able to say definately that someone cannot be the parent. If that is the issue, you need to have a DNA test.