Association between maternal ABO blood group and preeclampsia: a prospective cohort study

Preeclampsia is a leading cause of maternal morbidity and mortality. Various predictive methods exist, but none are without flaws. Risk factors vary in different women and at different gestational ages; hence, investigating non-modifiable factors, such as ABO and Rhesus blood groups, may aid prediction and early detection of preeclampsia.

This study aimed to evaluate the association between maternal ABO blood groups and preeclampsia.

This was a prospective cohort study.

This study included singleton, normotensive, Rhesus-positive primigravidae with different ABO blood groups at <20 weeks of gestation. The primary outcome was the incidence of preeclampsia in mothers with Rhesus (D)-positive ABO blood groups (O, A, B and AB), while the secondary outcomes were the overall preeclampsia incidence and the odds ratio for preeclampsia between blood group O and non-O (A, B and AB) participants.

A total of 264 participants were enrolled, with 244 followed up until delivery. Eighteen participants developed preeclampsia with an incidence of 7.4% (95% confidence interval: 3.9-10.7). Most participants had blood group O (57.0%), followed by A (29.5%), B (12.7%) and AB (0.8%). The mean gestational age at preeclampsia onset was 37.8 ± 2 weeks. Blood group AB had the highest incidence of preeclampsia (50%), followed by B (16.1%), O (5.8%) and A (5.6%). Among 105 participants with non-O blood groups, 10 developed preeclampsia (p = 0.265). The adjusted odds ratio for the non-O blood group who developed preeclampsia was 1.65.

Maternal ABO blood group was not significantly associated with preeclampsia incidence. However, blood group AB exhibited the highest preeclampsia incidence compared with the other blood groups.