Abstract
Objective Randomized trials showed no improvement in pregnancy outcomes with the use of low
molecular weight heparin (LMWH) to prevent placenta-mediated pregnancy complications
(PMPCs) among thrombophilic women. However, the effect of treatment on placental findings
was not examined. We aimed to examine the occurrence of placental vascular lesions
in thrombophilic women treated with LMWH dose adjusted according to anti-factor Xa
compared with a fixed dose.
Study Design This study was a secondary analysis of a randomized trial designed to examine whether
LMWH dose adjusted according to anti-factor Xa levels compared with a fixed dose would
reduce the risk of PMPC. Eligible women were randomly allocated in a 1:1 ratio to
either a fixed dose of 40 mg daily LMWH (fixed dose group) or adjusted dose according
to anti-factor Xa levels (adjusted dose group). Placentas were examined by the same
perinatal pathologist who was blinded to group allocation. The primary outcome for
this analysis was the incidence of maternal placental vascular lesions.
Results During the study period, 88 placentas were examined; 41 and 47 from the fixed and
adjusted dose groups, respectively. Demographics, obstetrics and types of thrombophilias
were similar between the groups. Maternal placental vascular lesions were observed
in 23 (56.1%) and 21 (44.68%) placentas (p = 0.28) and foetal placental vascular lesions in 2 (4.88%) and 1 (2.13%) placentas
(p = 0.59) in the fixed and adjusted groups, respectively.
Conclusion Adjusted dose of enoxaparin according to anti-factor Xa levels compared with a fixed
dose did not affect placental vascular lesions in thrombophilic women.
Keywords
low molecular weight heparin - thrombophilia - pregnancy - placental vascular lesions
- adjusted dosage
