Low molecular weight heparin versus no treatment in women with previous severe pregnancy complications and placental findings without thrombophilia.

Low molecular weight heparin (LMWH) treatment has been recommended for pregnant women with previous adverse pregnancy and who were diagnosed as having a thrombophilia. We now examined the effect of LMWH on pregnant women without thrombophilias who had severe pregnancy complications and placental vasculopathy in an earlier pregnancy. Seventy-two women with a history of severe preeclampsia, fetal growth restriction (FGR) less than fifth percentile, severe placental abruption and/or stillbirth after 20 weeks, whose thrombophilia workup was negative, were enrolled. Placental vasculopathy was defined as villous infarcts, fibrinoid necrosis of decidual vessels, fetal vessel thrombosis, evidence of placental abruption and perivillous fibrin deposition. The study group consisted of 32 pregnant women who were treated with LMWH and 40 pregnant women who were not treated with LMWH (control group) in their ensuing pregnancy in our institution between 2003 and 2007. The incidences of severe preeclampsia, FGR, placental abruption and stillbirth in the previous pregnancies were similar for both groups. The incidences of severe preeclampsia and placental abruption in the study group in the index pregnancy were significantly lower than the control group (3.13 versus 20%, P = 0.03; and 0 versus 15%, P = 0.03, respectively). The respective incidence of FGR was 6.25 versus 22.5%, and of overall adverse outcome was 9.4 versus 60% (P = 0.001). Treatment with LMWH may reduce the rate of the recurrence of severe pregnancy complications and significant placental vasculopathy in women without thrombophilias.