Can baby have b positive blood type if mother is o and father ab positive?

No, a baby cannot have a B positive blood type if the mother is O and the father is AB positive.

Blood type is determined by the presence or absence of two antigens, A and B, on the surface of red blood cells. A person with type A blood has only A antigens, a person with type B blood has only B antigens, a person with type AB blood has both A and B antigens, and a person with type O blood has neither A nor B antigens.

The ABO blood group is inherited, with each person inheriting one allele from each parent. The alleles are A, B, and O. A person with two A alleles has type A blood, a person with two B alleles has type B blood, a person with one A allele and one B allele has type AB blood, and a person with two O alleles has type O blood.

In this case, the mother has type O blood, which means she has two O alleles. The father has type AB blood, which means he has one A allele and one B allele. When these parents have a child, the child can only inherit an O allele from the mother and either an A or a B allele from the father. Therefore, the child can only have type A blood or type B blood, not type B positive blood.