Recurrence and severity of abnormal pregnancy outcome in patients treated by low-molecular-weight-heparin : a prospective pilot study

Objective This prospective pilot study assesses the recurrence rate and severity of abnormal pregnancy outcome (APO), excluding early pregnancy complications, in pregnant patients, without acquired thrombophilia, treated by prophylactic doses of LMWH, independently from their congenital thrombophilic condition. Methods We recruited a cohort of 128 pregnant patients with previous APO; 100 of whom with APO and intrauterine growth restriction (IUGR), and 28 with maternal APO only. LMWH treatment was started at recruitment. Composite cross over recurrence rate IUGR, gestational hypertension, preeclampsia, HELLP, abruptio was analyzed. The main outcome measure was severe APOs with iatrogenic delivery ≤ 32 weeks of gestation. Results Median gestational age at LMWH treatment was 20 weeks. Severe APO decreased in treated pregnancies from 45% to 4% (R.R.=0.3, CI .95=0.2-0.8). This value was not significantly different in thrombophilic and non thrombophilic patients. When severe and minor complications were analyzed altogether the recurrence rate was 28%. In patients with APO and FGR in the index pregnancy, newborn weights were significantly better in the treated pregnancy: 1090g (1035-1145) vs. 850g (535-1200), P<0,01) Conclusions. Prophylactic regimen of LMWH significantly reduced the recurrence rate of severe composite APO in pregnancies affected in the index pregnancy by APO and fetal growth restriction or SGA newborns. This result was independent from the patients' inherited thrombophilic conditions