ABO Incompatibility and parity effects on perinatal mortality

Abstract

The perinatal mortality rate is known to increase with parity. This parity effect is shown to be steepest for “O"‐type mothers, compared to mothers with blood groups A, B, or AB. Thus, there is a heightened parity effect in mothers who are likeliest to be antigenically dissimilar from their fetuses. This model may also be germane to other clinical conditions where negative parity effects are observed. Maternal‐fetal immunoreactivity is a likely explanation for parity effects on perinatal mortality attributable to ABO incompatibility and may also contribute to the occurrence of negative parity effects in other conditions.