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Keywords:

  • Gestational hypertension;
  • pre-eclampsia;
  • risk factors

Please cite this paper as: Lee B, Zhang Z, Wikman A, Lindqvist P, Reilly M. ABO and RhD blood groups and gestational hypertensive disorders: a population-based cohort study. BJOG 2012;119:1232–1237.

Objective  To examine the association between ABO and RhD blood groups and gestational hypertensive disorders in a large population-based cohort.

Design  Cohort study. Risks of gestational hypertensive disorders, pre-eclampsia, and severe pre-eclampsia, estimated by odds ratios for maternal ABO blood group and RhD status.

Setting  National health registers of Sweden.

Population  All singleton deliveries in Sweden born to first-time mothers during the period 1987–2002 [total = 641 926; any gestational hypertensive disorders, = 39 011 (6.1%); pre-eclampsia cases, = 29 337 (4.6%); severe pre-eclampsia cases, = 8477 (1.3%)].

Methods  Using blood group O as a reference, odds ratios of gestational hypertensive disorders, pre-eclampsia, and severe pre-eclampsia were obtained from logistic regression models adjusted for potential confounding factors.

Main outcome measures  Gestational hypertensive disorders, pre-eclampsia, and severe pre-eclampsia.

Results  Compared with blood group O, all non-O blood groups had modest but statistically significantly higher odds of pre-eclampsia. Blood group AB had the highest risk for pre-eclampsia (OR = 1.10, 95% CI 1.04–1.16) and severe pre-eclampsia (OR = 1.18, 95% CI 1.07–1.30). RhD-positive mothers had a small increased risk for pre-eclampsia (OR = 1.07, 95% CI 1.03–1.10).

Conclusions  In the largest study on this topic to date, women with AB blood group have the highest risks of gestational hypertensive disorders, pre-eclampsia, and severe pre-eclampsia, whereas women with O blood group have the lowest risks of developing these disorders. Although the magnitude of increased risk is small, this finding may help improve our understanding of the etiology of pre-eclampsia.