The blood types of babies born to father type A and mother type O are type A and type O. Since ABO blood type follows the autosomal dominant inheritance law, and in ABO blood type in the gene expression is only the pure chromosome, that is, in the gene expression only exists AA, AO, BB, BO, AB, OO, the six ways. If the father is type A, his gene expression may be AA and AO; if the mother is type O, her gene expression is OO. The possible gene expression of the babies born to the two is AO, OO, that is, type A, O blood. Dad A mother O type baby’s blood type may be A type may also be O type, are normal blood type, no need to worry too much, the above is for reference only, such as physical discomfort, need to consult a doctor in a timely manner to avoid aggravation of the condition.