Pre-eclampsia is an important cause of maternal morbidity and mortality. Its etiology
is still unknown. Clinical symptoms correlate with activation of coagulation and inherited
thrombophilia has been associated with pre-eclampsia. ABO blood group has been associated
with thrombotic disorders and pre-eclampsia. We assessed ABO blood group, seven thrombophilia
associated polymorphisms, and anti-beta2-glycoprotein I antibodies as risk factors
for pre-eclampsia.
We performed a population-based nested case-control study of 100,000 consecutive pregnancies
in Finland. Cases and controls were identified by combining national registers and
medical records were reviewed. We studied 248 cases fulfilling strict criteria for
pre-eclampsia and 679 controls. Severe pre-eclampsia, early pre-eclampsia, and pre-eclampsia
with intra-uterine growth restriction (IUGR) were analyzed separately.
Blood group AB increased the risk for pre-eclampsia as a whole (OR 2.1, 95% CI 1.3-3.5),
and in the three subgroups (OR 2.3, 3.8, 3.4; 95% CI 1.3-3.9, 2.0-7.1, 1.6-7.1). FV
Leiden increased the risk as a whole (OR 1.7, 95% CI 0.8-3.9), and in the three subgroups,
although not statistically significantly. Anti-beta2-glycoprotein I antibodies were
not associated with pre-eclampsia. High body mass index, diabetes, first pregnancy,
and twin pregnancy increased the risk from 1.5-fold to 8.2-fold.
Our results confirm and extend the prior observation of blood group AB being a risk
factor for pre-eclampsia. ABO blood group is known from all pregnant women. The value
of blood group as risk factor for pre-eclampsia should be further assessed in prospective
studies. In this study, FV Leiden was not statistically significant risk factor.