Objective: To determine whether specific subtypes of early-onset hypertensive disorders of pregnancy (haemolysis, elevated liver enzymes, low platelets [HELLP] syndrome; severe preeclampsia; eclampsia; and fetal growth restriction) differ in increased prevalences of thrombophilic disorders.
Design: Cohort study.
Setting: Two university hospitals in Amsterdam, the Netherlands.
Population: 216 patients participating in a randomized clinical trial with severe and early-onset hypertensive disorders of pregnancy.
Methods: More than 3 months after delivery, all patients were invited for a thrombophilia screening protocol, including hereditary thrombophilic disorders (Factor II or V-Leiden mutation, APC-resistance, protein S deficiency), antiphospholipid antibodies (anticardiolipin antibodies and lupus anticoagulant activity), and hyperhomocysteinemia (before and after methionin challenge). Disease expression was classified by HELLP syndrome, severe preeclampsia, or neonatal birth weight ratio below the median (0.65). Univariate and multinomial regression analyses examined the association of disease expression with thrombophilic disorders, and other associated factors (chronic hypertension, smoking, body mass index, positive family history of cardiovascular morbidity, and demographic parameters).
Main outcome measures: incidence of thrombophilic disorders in different subtypes of disease.
Results: Overall prevalence of thrombophilic disorders in 206 (95%) screened women was 36%. Chronic hypertension was present in 32%, and 34% had a positive family history of cardiovascular morbidity. Multinomial regression analysis showed that hereditary thrombophilia was more frequent among women with infants with a birth weight ratio <0.65 than in women with HELLP syndrome or severe preeclampsia (p = 0.01, OR 5.1 (1.5 to 7.3) and OR 3.4 (1.1 to 10.6), respectively). High body mass index was less frequent in women with HELLP syndrome than in those with severe preeclampsia or fetal growth restriction (p = 0.06, OR 0.5 (0.3 to 0.9) and OR 0.4 (0.2 to 1.0), respectively).
Conclusion: In this population, the high prevalence of thrombophilic factors and chronic hypertension was confirmed. There were small differences between groups. Hereditary thrombophilic disorders were associated with fetal growth restriction but not with type of maternal disease, suggesting an effect on placental function. Maternal body mass index was lower in women with HELLP syndrome.