Inherited thrombophilia and pregnancy loss

Low molecular weight heparin use in unexplained recurrent miscarriage

Objective: The aim of the study was to investigate whether the use of low molecular weight heparin (LMWH) improve live birth rates when compared with control group in patients with unexplained recurrent miscarriages (URM).

Methods: In this prospective observational study 150 women with a history of two or more previous unexplained first trimester pregnancy loss who received LMWH; either enoxaparin (n=50), tinzaparin (n=50) or nothing (n=50) were followed for the pregnancy outcome measures. Only the patients who have used standardized dosage of LMWH (4000 IU/day enoxaparin or 3500 IU/day tinzaparin ) were included to the study. The primary end point was the live birth rate and secondary end points were the side effects, late pregnancy complications and neonatal outcome in the study cohorts.

Results: Live birth was achieved 85% of the LMWH group and 66% of the control group (p=0.007). According to the subgroup analysis; live birth rates did not differ significantly between the enoxaparin and tinzaparin group (84% and 86%, respectively). Maternal and neonatal side effects were not statistically significant among the study participants.

Conclusion: Thromboprophylaxis with LMWH resulted in a improved live-birth rate in patient with 2 or more consecutive unexplained recurrent pregnancy loss. Nevertheless these findings need to be confirmed in larger randomized trials.

Low-molecular-weight heparin to prevent postpartum venous thromboembolism. A pilot randomised placebo-controlled trial

The risk of venous thromboembolism (VTE) is elevated in the postpartum period. Low-molecular-weight heparin (LMWH) reduces the risk of VTE in many settings but is costly, inconvenient and increases bleeding. Randomised controlled trials (RCT) are required to determine if LMWH prophylaxis provides a clinical benefit in high-risk postpartum women. We sought to determine if a placebo-controlled RCT was feasible. We conducted a multi-national, double-blind pilot RCT in "high risk" postpartum women comparing 21 days of prophylactic dose LMWH to identical saline placebo injections. The primary pilot outcome was mean number of recruited women per centre per month. The planned primary outcome for the full trial was symptomatic objectively confirmed VTE or asymptomatic proximal deep-vein thrombosis diagnosed by a screening bilateral leg vein ultrasound at day 21. In six centres, a total of 1,346 potentially eligible women were approached to participate; 968 were ineligible, leaving 378 (31.5%) eligible patients. Of these, only 25 (6.6%) were randomised at a rate of 0.7 per centre per month. The primary reasons for declining participation were to avoid study injections and being too overwhelmed to participate in research. None of the participants had a VTE during follow-up. In conclusion, despite an adequate number of eligible participants, our double-blind RCT design was not feasible due to a very low consent rate. Other experimental approaches may be necessary to generate evidence in this important area of research.

The association of factor V leiden and prothrombin gene mutation and placenta-mediated pregnancy complications: a systematic review and meta-analysis of prospective cohort studies

BACKGROUND

Factor V Leiden (FVL) and prothrombin gene mutation (PGM) are common inherited thrombophilias. Retrospective studies variably suggest a link between maternal FVL/PGM and placenta-mediated pregnancy complications including pregnancy loss, small for gestational age, pre-eclampsia and placental abruption. Prospective cohort studies provide a superior methodologic design but require larger sample sizes to detect important effects. We undertook a systematic review and a meta-analysis of prospective cohort studies to estimate the association of maternal FVL or PGM carrier status and placenta-mediated pregnancy complications.

METHODS AND FINDINGS

A comprehensive search strategy was run in Medline and Embase. Inclusion criteria were: (1) prospective cohort design; (2) clearly defined outcomes including one of the following: pregnancy loss, small for gestational age, pre-eclampsia or placental abruption; (3) maternal FVL or PGM carrier status; (4) sufficient data for calculation of odds ratios (ORs). We identified 322 titles, reviewed 30 articles for inclusion and exclusion criteria, and included ten studies in the meta-analysis. The odds of pregnancy loss in women with FVL (absolute risk 4.2%) was 52% higher (OR = 1.52, 95% confidence interval [CI] 1.06-2.19) as compared with women without FVL (absolute risk 3.2%). There was no significant association between FVL and pre-eclampsia (OR = 1.23, 95% CI 0.89-1.70) or between FVL and SGA (OR = 1.0, 95% CI 0.80-1.25). PGM was not associated with pre-eclampsia (OR = 1.25, 95% CI 0.79-1.99) or SGA (OR 1.25, 95% CI 0.92-1.70).

CONCLUSIONS

Women with FVL appear to be at a small absolute increased risk of late pregnancy loss. Women with FVL and PGM appear not to be at increased risk of pre-eclampsia or birth of SGA infants. Please see later in the article for the Editors' Summary.

Low protein Z levels, but not the intron F G79A polymorphism, are associated with unexplained pregnancy loss

INTRODUCTION

The present case-control study was designed in order to investigate the association between plasma protein Z (PZ) levels, the intron F G79A polymorphism and unexplained pregnancy loss.

MATERIALS AND METHODS

51 women with at least two consecutive or three non-consecutive fetal losses between the 8th and 12th week of gestation and 47 apparently healthy parous women of reproductive age with no history of pregnancy loss (controls) were enrolled. Allele frequencies of the PZ intron F G79A polymorphism and PZ levels were measured.

RESULTS

PZ levels (mg/L) were significantly lower in cases (mean +/- S.D. 1.28 +/- 0.56) than controls (1.97 +/- 0.76, p < 0.001) and in carriers of the A allele (1.46 +/- 0.62), compared to GG homozygous subjects (1.72 +/- 0.81, p = 0.044). A higher proportion of cases (41.2%) were PZ-deficient (<1 mg/L), compared to controls (10.6%, p = 0.001). No significant difference in the frequency of at least one A allele carriers was observed between cases (39.2%) and controls (40.4%).

CONCLUSION(S)

It is possible that low PZ levels are a novel risk factor for unexplained recurrent miscarriage or fetal death. The presence of the F 79A allele is associated with significantly lower PZ levels, but, in the present study, was unrelated to unexplained early pregnancy loss.

Inherited Thrombophilia

Inherited thrombophilia can be defined as a genetically determined predisposition to the development of thromboembolic complications. Since the discovery of activated protein C resistance in 1993, several additional disorders have been described and, at present, it is possible to identify an inherited predisposition in about 60 to 70% of patients with such complications. These inherited prothrombotic risk factors include qualitative or quantitative defects of coagulation factor inhibitors, increased levels or function of coagulation factors, defects of the fibrinolytic system, altered platelet function, and hyperhomocysteinemia. In this review, the main inherited prothrombotic risk factors are analyzed from epidemiological, laboratory, clinical, and therapeutic points of view. Finally, we discuss the synergism between genetic and acquired prothrombotic risk factors in particular conditions such as childhood and pregnancy.

Long-term dalteparin in pregnancy not associated with a decrease in bone mineral density: substudy of a randomized controlled trial

BACKGROUND

The risk of decreased bone mineral density (BMD) with prophylactic dose long-term low-molecular-weight heparin (LMWH) is unknown.

OBJECTIVES

We sought to determine whether long-term prophylactic dalteparin in pregnancy leads to loss of BMD.

PATIENTS/METHODS

Patients in a substudy of an ongoing multicenter randomized trial investigating the effect of antepartum dalteparin prophylaxis on pregnancy outcomes in thrombophilic pregnant women were randomized to either dalteparin 5000 U s.c. daily until 20 weeks and then 5,000 U s.c. q12 h until >37 weeks or to the control group. The primary outcome was absolute spine BMD at six weeks postpartum.

RESULTS

Of 77 patients eligible for the BMD substudy, 62 were analyzed. 33 patients received a mean of 212 days of dalteparin in the intervention group. 29 patients received a mean of 38 days of postpartum dalteparin in the control group. There was no difference in mean BMD between the intervention (1.11 g cm(-2)) and the control groups (1.14 g cm(-2)). Similarly, there was no difference in T-scores; the difference of -0.34 (95% confidence interval -0.93 to +0.25) in favor of the control group excludes a clinically important increase in fracture risk.

CONCLUSIONS

Our results suggest that the use of long-term prophylactic dalteparin in pregnancy is not associated with a significant decrease in BMD.

CLINICAL TRIAL REGISTRATION

ISRCTN87441504 at http://www.controlled-trials.com.

Effects of enoxaparin on late pregnancy complications and neonatal outcome in women with recurrent pregnancy loss and thrombophilia: results from the Live-Enox study

Women with thrombophilia and a history of recurrent pregnancy loss have poor pregnancy outcomes. Prophylaxis with enoxaparin 40 mg/day or 80 mg/day resulted in favorable gestational and neonatal outcomes.

Pregnancy and its management in the Philadelphia negative myeloproliferative diseases

The myeloproliferative diseases (MPDs) present several therapeutic challenges in patients of childbearing potential. The most extensive literature exists for patients with essential thrombocythaemia, with over 200 pregnancies reported in retrospective case series. Yet there is conflicting data in relation to predicting pregnancy outcome and optimal management strategy. Pregnancy is less frequently reported for polycythaemia vera and myelofibrosis. There is a need for collaboration to further our knowledge in this field. Here, the literature is reviewed in detail and experience of different therapeutic strategies in pregnancy discussed. There is increasing understanding about the pathogenesis of placental dysfunction in inherited thrombophilia and antiphospholipid antibody syndrome pregnancy outcomes in these conditions parallel those reported for MPDs. Furthermore several large studies have influenced pregnancy management in these conditions and, whilst not directly applicable to MPDs, this data have potential to inform treatment protocols. This data are reviewed and a personal management strategy for pregnancy in MPD proposed.