Relationship between maternal ABO blood groups and pregnancy outcomes: a retrospective cohort study in Dongguan, China.

What is already known on this subject? The relationship between blood type and disease is being increasingly studied. With regard to the relationship between maternal blood type and pregnancy outcomes, some studies have focused on people undergoing in vitro fertilisation. There are few reports on healthy women.What do the results of this study add? Compared to mothers with type B blood, the RR of foetal stillbirth in mothers with type A blood was 2.87 (95% CI: 1.70, 4.85), and compared to mothers with type O blood, the RR was 1.72 (95% CI: 1.16, 2.55). Compared with foetuses of other three blood type mothers, foetuses of A blood type mothers have a higher median birth weight (P = 0.011).What are the implications of these findings for clinical practice and/or further research? This study is the first to explore the relationship between blood type and pregnancy outcomes in healthy women.These results can provide some clues for the study of the mechanism of pregnancy outcomes.