Low molecular weight heparins for prevention of placental insufficiency: clinical and morphological aspects

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To compare efficacy of treatment with low molecular weight heparins (LMWH) initiated at different terms of gestation for prevention of placental insufficiency.

Material and methods

We studied 40 placentas from patients who were receiving LMWH during pregnancy because of a history of preeclampsia, elevated liver enzymes and low platelet count syndrome, intrauterine fetal death, fetal growth retardation. Patients were distributed into three groups. Twelve patients from the 1st group started treatment with LMWH before pregnancy, 14 patients from the 2nd group were treated from the first trimester of pregnancy and 14 patients from the 3rd group started anticoagulation when placental insufficiency was detected. We estimated weight, length and width of placenta and placenta-fetus ratio and conducted morphometric analysis of the villous tree, terminal villi and its vascularization.


Early treatment with LMWH before pregnancy or from the early stages of pregnancy was associated with a lower prevalence of branching angiogenesis, a better vascularization of placenta and a lower frequency of placental insufficiency. A rate of placental insufficiency, pre-eclampsia and fetal growth retardation was significantly lower in patients who started treatment earlier.


In women with a history of placental insufficiency treatment with LMWH should be started at a pregravid stage.

Key words

Аngiogenesis, intrauterine growth retardation, low-molecular-weight heparin, placenta, preeclampsia.