Managing a Pregnancy in the Presence of the Rare Blood Group Antibody PP1Pk.

Pregnant women with p phenotype, who lack antigens P, P1, and Pk, spontaneously form anti-PP1Pk antibodies whose primary target is the placenta. The risk of miscarriage in these women is 50%-70% and reaches 87% in the second trimester. The therapies aim to reduce the titer of antibodies early in pregnancy.