Gestational Outcome in Thrombophilic Women with Recurrent Pregnancy Loss Treated by Enoxaparin

A retrospective study of the management and outcomes of pregnancies with inherited antithrombin deficiency

INTRODUCTION

Antithrombin (AT) deficiency is a rare but highly thrombogenic inherited thrombophilia. Its association with adverse pregnancy outcomes (APO) is undefined. There is limited guidance on managing AT deficiency in pregnancy. Some significant issues remain controversial, including risk assessment for prophylactic anticoagulation, anticoagulant therapy, and monitoring. Our goal was to examine if the antepartum management of patients with AT deficiency affected their pregnancy outcomes.

MATERIALS AND METHODS

This retrospective, single-center observational study included pregnant women with inherited AT deficiency in Peking Union Medical College Hospital between 2013 and 2024.

RESULTS

Seventeen pregnancies in 6 women with AT deficiency were identified. A total of 7 pregnancies received adjusted-dose low-molecular-weight heparin (LMWH) and were monitored by anti-Xa level, AT activity, and D-dimer. There were 5 live births (all received LMWH), 7 second-trimester abortions (1 received LMWH), and 5 early pregnancy losses (1 received LMWH). There were 5 abruptio placentae events (3 received LMWH) and 7 thrombotic events (2 received LMWH).

CONCLUSIONS

AT deficiency is at least an important partial factor contributing to APO. It is suggested to make a full assessment of AT patients both for venous thrombus embolism and APO risk. We observed a high prevalence of heparin resistance and a positive correlation between adequate anticoagulation and pregnancy outcome based on tight monitoring with anti-Xa level and timely adjustment of the LMWH dosage.

Investigation of serum trimethylamine-N-oxide levels in missed abortion: A prospective study

OBJECTIVE

The aim of our study was to investigate the relationship between missed abortion and serum trimethylamine N-oxide (TMAO) levels.

METHODS

A total of 129 patients with 56 missed abortions and 73 healthy pregnancies were included in our study. Patients who had more than one pregnancy loss, had systemic disease (hypertension, diabetes, rheumatologic disease, hematologic disease, and so forth) and did not accept to participate in the study were excluded. Pregnant women who did not have a fetal heartbeat in the first 20th week of pregnancy were considered as missed abortion. Demographic characteristics of the patients were recorded. The serum TMAO levels of these patients were compared with the serum TMAO levels of healthy pregnant women with the same gestational week between the two groups.

RESULTS

The median (IQR) serum level of TMAO was significantly higher in woman with missed abortus compared to the healthy controls (201.5 [IQR, 129.75-345] vs 150 [IQR, 86.9-273], U = 1534, P = 0.015, rrb = 0.25 [95% CI: 0.05-0.43]). We observed a positive and significant relationship between serum TMAO levels and age of the patients (Spearman's rho = 0.272 [95% CI: 0.01-0.50], P = 0.043). However, no significant relationship was found between serum TMAO levels and BMI (Spearman's rho = 0.093 [95% CI: -0.18 to 0.35], P = 0.496).

CONCLUSION

In our study, we found that the serum TMAO level was higher in patients with missed abortion compared to healthy pregnancies. Serum TMAO levels measured at early gestational weeks can provide information about the course of pregnancy.

Evaluation of T cell cytokines and their role in recurrent miscarriage

Recurrent miscarriage (RM) is defined as two or more consecutive pregnancy losses that affect approximately 5% of conceived women worldwide. RM is a multi-factorial reproductive problem and has been associated with parental chromosomal abnormalities, embryonic chromosomal rearrangements, uterine anomalies, autoimmune disorders, endocrine dysfunction, thrombophilia, life style factors, and maternal infections. However, the exact cause is still undecided in remaining 50% of cases. Immunological rejection of the embryo due to exacerbated maternal immune reaction against paternal embryonic antigens has been set forth as one of the significant reason for RM. The accurate means that shield the embryo during normal pregnancy from the attack of maternal immune network and dismissal are inadequately implicit. However, it is suggested that the genetically irreconcilable embryo escapes maternal immune rejection due to communication among many vital cytokines exuded at maternal-embryonic interface both by maternal and embryonic cells. Previous investigations suggested the Th1/Th2 dominance in altered immunity of RM patients, according to which the allogenic embryo flees maternal T cell reaction by inclining the Th0 differentiation toward Th2 pathway resulting into diminished pro-inflammatory Th1 immunity. However, recently pro-inflammatory Th17 cells and immunoregulatory Treg cells have been discovered as essential immune players in RM besides Th1/Th2 components. Cytokines are believed to develop a complicated regulatory network so as to establish a state of homeostasis between the semi-allogenic embryo and the maternal immune system. However, an adverse imbalance among cytokines at maternal-embryonic interface perhaps due to their gene polymorphisms may render immunoregulatory means not enough to re-establish homeostasis and thus may collapse pregnancy.

The physiologic anticoagulant and anti-inflammatory role of heparins and their utility in the prevention of pregnancy complications

Accumulating evidence supports the concept of increased thrombin generation, placental vascular lesions, and inflammation as crucial points in the development of the great obstetrical syndromes [preeclampsia, intrauterine growth restriction (IUGR), preterm labor (PTL), preterm prelabor rupture of membranes (PROM), fetal demise and recurrent abortions]. In light of this, the role of heparins for primary or secondary prevention of these syndromes is becoming more and more apparent, mainly due to the antithrombotic and anti-inflammatory effects of heparins. There is agreement regarding the use of heparin in the prevention of gestational complications in patients with antiphospholipid syndrome, while its use for other obstetrical complications is under debate. In the present review we will describe the physiologic role of heparins on coagulation and inflammation and we will discuss current evidence regarding the use of heparins for the prevention/ treatment of obstetrical syndromes.

Enoxaparin and Aspirin Compared With Aspirin Alone to Prevent Placenta-Mediated Pregnancy Complications: A Randomized Controlled Trial

OBJECTIVE

To evaluate whether daily enoxaparin, added to low-dose aspirin, started before 14 weeks of gestation reduces placenta-mediated complications in pregnant women with previous severe preeclampsia diagnosed before 34 weeks of gestation.

METHODS

In this open-label multicenter randomized trial, we enrolled consenting pregnant women with previous severe preeclampsia diagnosed before 34 weeks of gestation, gestational age at randomization of 7-13 weeks, singleton pregnancy, and no plan for anticoagulation. Eligible patients were randomly assigned to a one-to-one ratio to receive daily either 4,000 international units enoxaparin plus 100 mg aspirin or 100 mg aspirin alone. Randomization was done by a web-based randomization system. The primary composite outcome comprised maternal death, perinatal death, preeclampsia, small for gestational age (less than the 10th percentile), and placental abruption. A sample size of 232 women equally divided into two groups was needed to detect a significant reduction in primary outcome from 55% in the aspirin group to 36.7% in the enoxaparin-aspirin group (α: 0.05, β: 0.8, two-sided).

RESULTS

Between November 14, 2009, and February 21, 2015, 257 participants were enrolled. Baseline demographic and clinical factors were similar between groups. Eight women were excluded after randomization (six in the enoxaparin-aspirin group and two in the aspirin group), leaving 124 participants assigned to enoxaparin-aspirin and 125 to aspirin. Five participants were lost to follow-up (two in the enoxaparin-aspirin group and three in the aspirin group). There was no significant difference between the groups in the primary outcome: enoxaparin-aspirin 42 of 122 (34.4%) compared with aspirin alone 50 of 122 (41%) (relative risk 0.84, 95% confidence interval 0.61-1.16, P=.29). The occurrence of complications did not differ between the two groups.

CONCLUSION

Antepartum prophylactic enoxaparin does not significantly reduce placenta-mediated complications in women receiving low-dose aspirin for previous severe preeclampsia diagnosed before 34 weeks of gestation.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, https://clinicaltrials.gov, NCT00986765.

The Prevalence of Thrombophilia in Women With Recurrent Fetal Loss and Outcome of Anticoagulation Therapy for the Prevention of Miscarriages

OBJECTIVE

To estimate the prevalence of thrombophilia in women with recurrent miscarriages and to assess the effect of antithrombotic therapy.

DESIGN

A retrospective cohort study between the years 2004 and 2010.

SETTING

A hypercoagulation community clinic in northern Israel.

PATIENTS

Four hundred ninety pregnant women referred for thrombophilia screening.

MAIN OUTCOME MEASURES

Screening results for thrombophilia and antithrombotic treatment with enoxaparin, aspirin, or both and pregnancy outcomes.

RESULTS

The most common thrombophilia in our study group was factor V Leiden mutation with a prevalence of 20.9% followed by protein S deficiency with a prevalence of 19%. Live birth rate was higher in the group of women who received enoxaparin regardless of whether a specific thrombophilia could be found. This finding was more pronounced in women who had ≥4 miscarriages.

CONCLUSION

The prevalence of thrombophilia was higher in our study group than in the general population. Furthermore, treatment with enoxaparin might improve the rate of live births in women with or without evidence of thrombophilia, especially in women with ≥4 miscarriages.

Enoxaparin Use in Pregnancy: State of the Art

Low-molecular-weight heparin is the anticoagulant of choice in pregnancy. Enoxaparin has been increasingly used over the past 20 years in pregnant women at risk of thrombosis and pregnancy complications. The main indications are prophylaxis of venous thromboembolism and prevention of pregnancy loss in thrombophilic women. Other indications include treatment of venous thromboembolism, prophylaxis of arterial thrombosis in pregnant women with mechanical heart valves and prevention of late gestational complication such as pre-eclampsia and intrauterine growth restriction. Enoxaparin does not cross the placenta and is safe for the fetus. Maternal side effects are uncommon and include mild localized allergic reactions in 2% and increased bleeding in 2%, which is dose dependent. Heparin-induced thrombocytopenia is very rare and bone resorption is not clinically relevant. The mechanisms of action of enoxaparin in pregnancy are multiple and include anti-factor Xa (anti-Xa) activity in maternal circulation, tissue factor pathway inhibitor release from endothelial cells and trophoblasts at the placental level as well as anti-inflammatory effects.

Lessons From the EThIGII Trial

This study presents sample size considerations derived from the Efficacy of Thromboprophylaxis as an Intervention during Gravidity (EThIGII) trial (ClinicalTrials.gov: NCT00400387) to address the question of low-molecular-weight heparin (LMWH) treatment in women with recurrent pregnancy loss (RPL) depending on the M2/ANXA5 haplotype. To evaluate the possible influence of such treatment on miscarriage rates of trial participants, a post hoc analysis of ANXA5 promoter genotypes in the light of M2/ANXA5 ( RPRGL3) distribution was performed using logistic models. DNA for genotyping was available from 129 LMWH and 95 control patients, 44 (19.6%) of whom were M2/ANXA5 carriers. Miscarriages occurred in 1 (4.0%) of 25 M2/ANXA5 carriers from the LMWH group compared to 4 (21.1%) of 19 in the control group, resulting in an odds ratio (95% confidence interval) for miscarriage of 0.16 (0.016-1.5) for women treated with LMWH. In noncarriers, miscarriage rates were 6 (5.8%) of 104 versus 7 (9.2%) of 76 for the LMWH and the control groups, respectively, corresponding to an odds ratio for miscarriage of 0.60 (0.19-1.9). The apparent beneficial effects of miscarriage rate reduction in M2/ANXA5 carriers with RPL concur with biological considerations about improvement in reduced ANXA5 function through LMWH treatment in an adequate murine model. The data obtained were instrumental to design proper assessment of the existence and magnitude of this effect.

Pregnancy Loss, Polycystic Ovary Syndrome, Thrombophilia, Hypofibrinolysis, Enoxaparin, Metformin

Thrombophilia, hypofibrinolysis, and polycystic ovary syndrome (PCOS) are associated with recurrent pregnancy loss (RPL) and spontaneous abortion (SAB) alone and concurrently. The efficacy and safety of combined enoxaparin-metformin was prospectively assessed in women with PCOS with one or more previous SAB, thrombophilia, and/or hypofibrinolysis. Twenty-four white women with PCOS were studied; 23 with previous pregnancies, seven with RPL of unknown etiology (≥ three consecutive pregnancy losses <20 weeks’ gestation), two with two consecutive SABs, 13 with one SAB, and one with one live birth (HELLP syndrome). Prospectively, metformin (1.5 to 2.55 g/day) was administered before and throughout gestation, with concurrent enoxaparin (60 mg/day) throughout gestation. The 24 cases differed from 93 normal white female controls for the factor V Leiden mutation, 17% vs. 2%, Fisher’s p [pf] = .016, and for the 4G4G mutation of the plasminogen activator inhibitor-1 (PAI-1) gene (46% vs. 24%, Chi-square 4.63, p =. 031). The patients also differed from 44 normal white female controls for high levels (> 21.1 U/mL) of the PAI-1 gene product, plasminogen activator inhibitor activity (PAI-Fx) (33% vs. 8%, pf =. 018), and for high factor VIII (>150%) (22% vs. 0%, pf = .037). Of the 24 women, 23 had 65 previous pregnancies without metformin or enoxaparin, with 18 live births, 46 SAB (71%), and one elective abortion. On metforminenoxaparin, the same 23 women had 26 current pregnancies (28 fetuses), with 20 live births, two normal pregnancies 13 weeks or longer, and six SAB (21%), 3.4-fold lower than previous gestations (McNemar’s S = 33.6, p <. 0001). There were no adverse maternal or fetal therapy effects. Enoxaparin-metformin reduces pregnancy loss in women with PCOS with one or more previous SAB, who also have thrombophilia and/or hypofibrinolysis.

Effects of anticoagulant therapy on pregnancy outcomes in patients with thrombophilia and previous poor obstetric history

This study investigates the effects of anticoagulant therapy on pregnancy outcomes in 204 patients with thrombophilia and previous poor obstetric outcomes. Patients with poor obstetric history (pre-eclampsia, intrauterine growth retardation, fetal death, placental abruption, recurrent pregnancy loss) and having hereditary thrombophilia were included in this study. Poor obstetric outcomes were observed more frequently in patients who had not taken anticogulant therapy compared with treated group. Live birth rate, gestational age at birth and Apgar scores were significantly higher in the treated group when compared with the untreated group. There were no significant differences in terms of birthweight, mode of delivery and admission rates to the neonatal intensive care unit (NICU). Low-molecular-weight heparin (LMWH) plus acetylsalicylic acid (ASA) had higher gestational age at birth, Apgar scores, live birth rate and a lower abortion rates when compared with controls; in contrast, no significant difference was observed in terms of birthweight, mode of delivery, obstetric complications and admission rates to NICU. There were no significant differences between control group and both LMWH only and ASA only groups in terms of gestational age at birth, Apgar scores, birthweight, mode of delivery, obstetric complications and admission rates to NICU. Only LMWH group had higher live birth rate as compared with control group. The use of only ASA did not seem to affect the perinatal complication rates and outcomes. In conclusion, anticoagulant therapy with both LMWH and ASA seems to provide better obstetric outcomes in pregnant women with thrombophilia and previous poor obstetric outcomes.

Low-molecular-weight heparin for women with unexplained recurrent pregnancy loss: a multicenter trial with a minimization randomization scheme

BACKGROUND

A daily injection of low-molecular-weight heparin (LMWH) is often prescribed to women with unexplained recurrent pregnancy loss (RPL), although evidence suggesting a benefit is questionable.

OBJECTIVE

To determine whether LMWH increases ongoing pregnancy and live-birth rates in women with unexplained RPL.

DESIGN

Controlled, multicenter trial with randomization using minimization conducted from 2006 to 2013. (ClinicalTrials.gov: NCT00400387).

SETTING

14 university hospitals and perinatal care centers in Germany and Austria.

PATIENTS

449 women with at least 2 consecutive early miscarriages or 1 late miscarriage were included during 5 to 8 weeks' gestation after a viable pregnancy was confirmed by ultrasonography.

INTERVENTION

Women in the control group received multivitamin pills, and the intervention group received vitamins and 5000 IU of dalteparin-sodium for up to 24 weeks' gestation.

MEASUREMENTS

Primary outcome was ongoing pregnancy at 24 weeks' gestation. Secondary outcomes included the live-birth rate and late pregnancy complications.

RESULTS

At 24 weeks' gestation, 191 of 220 pregnancies (86.8%) and 188 of 214 pregnancies (87.9%) were intact in the intervention and control groups, respectively (absolute difference, -1.1 percentage points [95% CI, -7.4 to 5.3 percentage points]). The live-birth rates were 86.0% (185 of 215 women) and 86.7% (183 of 211 women) in the intervention and control groups, respectively (absolute difference, -0.7 percentage point [CI, -7.3 to 5.9 percentage points]). There were 3 intrauterine fetal deaths (1 woman had used LMWH); 9 cases of preeclampsia or the hemolysis, elevated liver enzyme level, and low platelet count (HELLP) syndrome (3 women had used LMWH); and 11 cases of intrauterine growth restriction or placental insufficiency (5 women had used LMWH).

LIMITATION

Placebo injections were not used, and neither trial staff nor patients were blinded.

CONCLUSION

Daily LMWH injections do not increase ongoing pregnancy or live-birth rates in women with unexplained RPL. Given the burden of the injections, they are not recommended for preventing miscarriage.

PRIMARY FUNDING SOURCE

Pfizer Pharma.

The physiologic and therapeutic role of heparin in implantation and placentation

Implantation, trophoblast development and placentation are crucial processes in the establishment and development of normal pregnancy. Abnormalities of these processes can lead to pregnancy complications known as the great obstetrical syndromes: preeclampsia, intrauterine growth restriction, fetal demise, premature prelabor rupture of membranes, preterm labor, and recurrent pregnancy loss. There is mounting evidence regarding the physiological and therapeutic role of heparins in the establishment of normal gestation and as a modality for treatment and prevention of pregnancy complications. In this review, we will summarize the properties and the physiological contributions of heparins to the success of implantation, placentation and normal pregnancy.

Aspirin and/or heparin for women with unexplained recurrent miscarriage with or without inherited thrombophilia

BACKGROUND

Since hypercoagulability might result in recurrent miscarriage, anticoagulant agents could potentially increase the chance of live birth in subsequent pregnancies in women with unexplained recurrent miscarriage, with or without inherited thrombophilia.

OBJECTIVES

To evaluate the efficacy and safety of anticoagulant agents, such as aspirin and heparin, in women with a history of at least two unexplained miscarriages with or without inherited thrombophilia.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (1 October 2013) and scanned bibliographies of all located articles for any unidentified articles.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials that assessed the effect of anticoagulant treatment on live birth in women with a history of at least two unexplained miscarriages with or without inherited thrombophilia were eligible. Interventions included aspirin, unfractionated heparin (UFH), and low molecular weight heparin (LMWH) for the prevention of miscarriage. One treatment could be compared with another or with no-treatment (or placebo).

DATA COLLECTION AND ANALYSIS

Two review authors (PJ and SK) assessed the studies for inclusion in the review and extracted the data. If necessary they contacted study authors for more information. We double checked the data.

MAIN RESULTS

Nine studies, including data of 1228 women, were included in the review evaluating the effect of either LMWH (enoxaparin or nadroparin in varying doses) or aspirin or a combination of both, on the chance of live birth in women with recurrent miscarriage, with or without inherited thrombophilia. Studies were heterogeneous with regard to study design and treatment regimen and three studies were considered to be at high risk of bias. Two of these three studies at high risk of bias showed a benefit of one treatment over the other, but in sensitivity analyses (in which studies at high risk of bias were excluded) anticoagulants did not have a beneficial effect on live birth, regardless of which anticoagulant was evaluated (risk ratio (RR) for live birth in women who received aspirin compared to placebo 0.94, (95% confidence interval (CI) 0.80 to 1.11, n = 256), in women who received LMWH compared to aspirin RR 1.08 (95% CI 0.93 to 1.26, n = 239), and in women who received LMWH and aspirin compared to no-treatment RR 1.01 (95% CI 0.87 to 1.16) n = 322).Obstetric complications such as preterm delivery, pre-eclampsia, intrauterine growth restriction and congenital malformations were not significantly affected by any treatment regimen. In included studies, aspirin did not increase the risk of bleeding, but treatment with LWMH and aspirin increased the risk of bleeding significantly in one study. Local skin reactions (pain, itching, swelling) to injection of LMWH were reported in almost 40% of patients in the same study.

AUTHORS' CONCLUSIONS

There is a limited number of studies on the efficacy and safety of aspirin and heparin in women with a history of at least two unexplained miscarriages with or without inherited thrombophilia. Of the nine reviewed studies quality varied, different treatments were studied and of the studies at low risk of bias only one was placebo-controlled. No beneficial effect of anticoagulants in studies at low risk of bias was found. Therefore, this review does not support the use of anticoagulants in women with unexplained recurrent miscarriage. The effect of anticoagulants in women with unexplained recurrent miscarriage and inherited thrombophilia needs to be assessed in further randomised controlled trials; at present there is no evidence of a beneficial effect.

Overview of low molecular weight heparin for preventative treatment of adverse obstetric outcomes related to abnormal placentation

Different proportions of cases of preterm and severe preeclampsia, placental abruption, fetal growth restriction, and fetal death share a common causal pathway of abnormal placental implantation. Documentation of an association between the risk of such adverse pregnancy outcomes (APOs) and inherited thrombophilias prompted initial studies to evaluate the benefit of anticoagulants for the prevention of recurrences both in patients with and without inherited thrombophilias. Prenatal administration of low molecular weight heparin (LMWH) has been evaluated in case control, cohort and randomized clinical trials. The evidence suggests a benefit of LMWH in the reduction of recurrences of APOs, with a number needed to treat of 6 (95% confidence interval: 4-10) to prevent one case of recurrent APOs. Such benefit is independent of the presence of inherited thrombophilias or the administration of low dose aspirin. Further studies are needed to establish the optimal duration for the prophylaxis, to better delineate the mechanism of action of LMWH and to explore the role, if any, of maternal serum markers and uterine artery Doppler findings in the modulation of the LMWH prophylaxis.

Antithrombotic treatment for pregnancy complications: which path for the journey to precision medicine?

Haemostatic and vascular biology mechanisms appear to play an important role in the pathogenesis of placenta-mediated pregnancy complications. Although low-dose aspirin (LDA) has a modest effect in preventing preeclampsia, antithrombotic interventions, LDA and low molecular weight heparin (LMWH) have not definitively proven their effectiveness in women with placenta-mediated pregnancy complications selected by previous pregnancy outcome alone. Given the heterogeneous aetiology of placenta-mediated pregnancy complications, it is critical to stratify patients according to maternal and fetal characteristics and disease mechanisms rather than simply by pregnancy outcome, such as miscarriage. Such stratification could identify those who could benefit from antithrombotic interventions in pregnancy. We lack data on genome-wide association studies, biomarkers and trials of interventions applied to specific homogeneous populations. Future studies should focus on elaborating different disease mechanisms and examining antithrombotic interventions in specific and more homogeneous groups, such as thrombophilic women with well-characterized placenta-mediated pregnancy complications, stratified by disease severity and pathological findings. Because of fetal safety concerns with new anticoagulants, the intervention should focus on heparins alone or in combination with LDA. Thus, placenta-mediated pregnancy complications deserve precision medicine, defining disease by mechanism rather than outcome with interventions focused on a more personalized approach.

Clinical application of enoxaparin

Low-molecular-weight heparins have several important advantages over unfractionated heparin (UFH). Due to a longer plasma half life together with high bioavailability and a linear dose-response relationship, the drugs can be safely and effectively administered in the hospital or ambulatory settings without the need to monitor the anticoagulant effect. Enoxaparin (Lovenox), Aventis Pharma) is a low-molecular-weight heparin which has been studied in a variety of clinical situations. In general surgery the efficacy of enoxaparin to prevent venous thromboembolism is similar to UFH but the tolerability is better. In patients undergoing cancer, orthopedic or vascular surgery the efficacy of enoxaparin is significantly higher with similar rates of bleeding complications. The database for enoxaparin in nonsurgical patients is smaller compared with surgical groups. There is evidence that the efficacy of enoxaparin may be superior to UFH in patients with severe cardiac disease. Efficacy and safety of UFH and enoxaparin are similar for the treatment of deep vein thrombosis. However, enoxaparin can be safely administered by the patients at home which is not possible with UFH. In patients with acute coronary syndromes, enoxaparin has been shown to reduce the rate of deaths and serious cardiac events in comparison with UFH. Furthermore, exonaparin treatment has been shown to be cost-effective, and therefore is the therapy of choice in this setting. In addition, enoxaparin has been shown to be a safe and effective alternative to the combination of UFH and phenprocoumone therapy in patients undergoing electrical cardioversion for atrial fibrillation.

Pregnancy and thrombophilia

The physiological changes that occur during pregnancy create a hypercoagulable milieu. This hypercoagulable state is thought to be protective, especially at the time of labor, preventing excessive hemorrhage. The presence of hereditary or acquired causes of thrombophilia during pregnancy tilts the balance in favor of unwanted venous thromboembolism and adverse pregnancy outcomes due to vascular uteroplacental insufficiency. These adverse pregnancy outcomes include recurrent pregnancy losses, intrauterine fetal death, intrauterine growth retardation, preeclampsia and placental abruption. Much of the current data with regards to the association of the different thrombophilias and pregnancy-related complications are based on retrospectively designed studies. This lack of randomization, in-homogeneity of patient populations, varying case definitions, selection biases and inadequately matched control populations, have given rise to conflicting data with regard to screening for, and treatment of, pregnant women with suspected thrombophilias. The limited data that we have support the use of anticoagulant drugs for the prevention of pregnancy-related complications in the setting of thrombophilia. Heparin and low-molecular-weight heparins are the anticoagulant drugs of choice as they do not cross the placental barrier and, hence, do not cause fetal anticoagulation or teratogenicity. Warfarin can be used from the 12th week of gestation onwards but is preferably reserved for the postpartum period.

Research methodology in recurrent pregnancy loss

The aim of this article is to highlight pitfalls in research methodology that may explain why studies in recurrent pregnancy loss (RPL) often provide very divergent results. It is hoped that insight into this issue may help clinicians decide which published studies are the most valid. It may help researchers to eliminate methodological flaws in future studies, which may hopefully come to some kind of agreement about the usefulness of diagnostic tests and treatments in RPL.

Antithrombotic therapy for pregnancy loss

BACKGROUND Although an association between thrombophilia and pregnancy loss has been observed in many studies, little is known about the pathophysiological mechanisms behind this association. Considering the association between thrombophilia and pregnancy loss, the efficacy of antithrombotic therapy for women with pregnancy loss (with or without thrombophilia) has been studied for the past 30 years. METHODS We performed a comprehensive review of the literature on the strength of the association between thrombophilia and pregnancy loss, the pathophysiological mechanisms and the efficacy of antithrombotic therapy to increase the chance of live birth. RESULTS The association between pregnancy loss and thrombophilia varies according to the type of thrombophilia (e.g. antiphospholipid syndrome versus forms of inherited thrombophilia) and according to the type of pregnancy loss (single versus recurrent pregnancy loss and early versus late pregnancy loss). Thrombophilia may induce thrombosis in decidual vessels or impair placentation through hypercoagulability and inflammation, but these hypotheses need further verification. For women with antiphospholipid syndrome, evidence from small-sized trials suggests a beneficial effect of antithrombotic therapy but additional randomized controlled trials are essential to confirm this. Whether antithrombotic therapy increases the chance of live birth in women with inherited thrombophilia is unknown. Recent randomized controlled trials have consistently shown that antithrombotic therapy does not increase the chance of live birth in women with unexplained recurrent miscarriage. CONCLUSIONS There are large gaps in knowledge and a lack of evidence for treatment of women with pregnancy loss with thrombophilia. To provide a solid base for clinical practice, further studies on the role of coagulation in reproduction, as well as international collaborations in randomized controlled trials of antithrombotic therapy in women with pregnancy loss, and antiphospholipid syndrome or inherited thrombophilia are urgently needed.

Safety and efficacy of low molecular weight heparin therapy during pregnancy: three year experience at a tertiary care center

PURPOSE

To evaluate safety and efficacy of low molecular weight heparin given for various indications during pregnancy.

METHODOLOGY

A detailed retrospective analysis of all the patients who received low molecular weight heparin (LMWH) for various indications over a period of 3 years (2010-2012) at a tertiary care hospital in Northern India was performed.

RESULTS

Fifty-five patients received LMWH over the period of 3 years, for various indications. Enoxaparin (1 mg/kg body weight OD/BD subcutaneously) was used. The indications were valvular heart disease with valve replacement, atrial fibrillation, or thrombus in 60 % patients; chronic deep vein thrombosis (DVT) in 7 % patients; thrombophilia in 9.1 % patients; recurrent pregnancy losses in 18 % patients; and DVT prophylaxis in 5.5 % patients. Abortion was seen in 7.2 % patients; fetal growth restriction in 10.9 % patients; and oligohydramnios, preeclampsia, gestational hypertension, placenta previa, abruptio placentae, and postpartum hemorrhage in 1.8 % patients. Stillbirth occurred in 3.6 % patients. No thromboembolic event was noted in any of the patients. None of the patients had any documented thrombocytopenia or clinical fracture.

CONCLUSION

Low molecular weight heparin can be used in pregnancy for various indications as an alternative to unfractionated heparin or warfarin as it is efficacious and safe.

Does Anticoagulant Therapy Improve Pregnancy Outcome Equally, Regardless of Specific Thrombophilia Type?

The study was conducted to evaluate the effect of anticoagulant therapy in women with thrombophilia and to detect the possible differences among carriers of mutations (factor V [FV] Leiden and FIIG20210) and those with natural anticoagulant deficiency. The 4-year prospective investigation included 85 pregnant women, with a history of recurrent fetal loss (RFL). They were treated with prophylactic doses of low-molecular-weight heparin (nadroparin) starting from 6 to 8 weeks of gestation. Pregnancy outcomes were evaluated based on the thrombophilia type. Carriers of thrombophilic mutations had a live birth rate of 93%, compared to 41.6% for women with natural anticoagulant deficiencies. Significant differences between the groups were also observed for intrauterine fetal death, intrauterine growth restriction, and postpartum thrombosis. The optimal therapy for women with natural anticoagulant deficiency and RFL remains unclear and future prospective study with a large number of patients is required to determine the best treatment for these severe thrombophilic conditions.

Emerging nonanticoagulant role of low molecular weight heparins on extravillous trophoblast functions and on heparin binding-epidermal growth factor and cystein-rich angiogenic inducer 61 expression

OBJECTIVE

To examine the effects of low molecular weight heparins (LMWHs) on extravillous trophoblast (EVTC) invasiveness and on EVTC expression/secretion of heparin binding-EGF (HB-EGF) and cystein-rich angiogenic inducer 61 (Cyr61), both of which are involved in the process of EVTC invasion. Furthermore, to investigate the intracellular DNA binding activity of activator protein (AP)-1.

DESIGN

Experimental study.

SETTING

Department of Obstetrics Gynecology, Università Cattolica del Sacro Cuore, Rome, Italy.

PATIENT(S)

Cultures of primary EVTC cells isolated from patients with first trimester unexplained recurrent miscarriage.

INTERVENTION(S)

The effects of LMWHs on EVTC invasiveness were examined by an in vitro matrigel invasion assay. Matrix metalloprotease-2 activity (MMP-2) was examined by gelatin zimography. HB-EGF and Cyr61 expression and secretion were studied by Western blot analysis and ELISA assay. AP-1 activity was measured through a multiwell colorimetric assay.

MAIN OUTCOME MEASURE(S)

The EVTC invasiveness, the expression/secretion of HB-EGF and Cyr61 proteins, and the AP-1 DNA binding activity in the presence of increasing concentrations of LMWHs were investigated.

RESULT(S)

Both LMWHs, and primarily tinzaparin, increased EVTC invasiveness, by enhancing the MMP-2 proteolytic activity, and induced the expression/secretion of HB-EGF and Cyr61 in EVTC. This effect was mediated by an increased DNA binding activity of AP-1.

CONCLUSION(S)

Both LMWHs are able to promote EVTC development because they are able to stimulate the EVTC invasive properties. Our results may provide a possible biological rationale for the clinical use of LMWH for placental-mediated pregnancy complications unrelated to prothrombotic disorders.

Maternal malaria induces a procoagulant and antifibrinolytic state that is embryotoxic but responsive to anticoagulant therapy

Low birth weight and fetal loss are commonly attributed to malaria in endemic areas, but the cellular and molecular mechanisms that underlie these poor birth outcomes are incompletely understood. Increasing evidence suggests that dysregulated hemostasis is important in malaria pathogenesis, but its role in placental malaria (PM), characterized by intervillous sequestration of Plasmodium falciparum, proinflammatory responses, and excessive fibrin deposition is not known. To address this question, markers of coagulation and fibrinolysis were assessed in placentae from malaria-exposed primigravid women. PM was associated with significantly elevated placental monocyte and proinflammatory marker levels, enhanced perivillous fibrin deposition, and increased markers of activated coagulation and suppressed fibrinolysis in placental plasma. Submicroscopic PM was not proinflammatory but tended to be procoagulant and antifibrinolytic. Birth weight trended downward in association with placental parasitemia and high fibrin score. To directly assess the importance of coagulation in malaria-induced compromise of pregnancy, Plasmodium chabaudi AS-infected pregnant C57BL/6 mice were treated with the anticoagulant, low molecular weight heparin. Treatment rescued pregnancy at midgestation, with substantially decreased rates of active abortion and reduced placental and embryonic hemorrhage and necrosis relative to untreated animals. Together, the results suggest that dysregulated hemostasis may represent a novel therapeutic target in malaria-compromised pregnancies.

VTE, thrombophilia, antithrombotic therapy, and pregnancy: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines

BACKGROUND

The use of anticoagulant therapy during pregnancy is challenging because of the potential for both fetal and maternal complications. This guideline focuses on the management of VTE and thrombophilia as well as the use of antithrombotic agents during pregnancy.

METHODS

The methods of this guideline follow the Methodology for the Development of Antithrombotic Therapy and Prevention of Thrombosis Guidelines: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines in this supplement.

RESULTS

We recommend low-molecular-weight heparin for the prevention and treatment of VTE in pregnant women instead of unfractionated heparin (Grade 1B). For pregnant women with acute VTE, we suggest that anticoagulants be continued for at least 6 weeks postpartum (for a minimum duration of therapy of 3 months) compared with shorter durations of treatment (Grade 2C). For women who fulfill the laboratory criteria for antiphospholipid antibody (APLA) syndrome and meet the clinical APLA criteria based on a history of three or more pregnancy losses, we recommend antepartum administration of prophylactic or intermediate-dose unfractionated heparin or prophylactic low-molecular-weight heparin combined with low-dose aspirin (75-100 mg/d) over no treatment (Grade 1B). For women with inherited thrombophilia and a history of pregnancy complications, we suggest not to use antithrombotic prophylaxis (Grade 2C). For women with two or more miscarriages but without APLA or thrombophilia, we recommend against antithrombotic prophylaxis (Grade 1B).

CONCLUSIONS

Most recommendations in this guideline are based on observational studies and extrapolation from other populations. There is an urgent need for appropriately designed studies in this population.

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.

Enoxaparin versus unfractionated heparin in the management of recurrent abortion secondary to antiphospholipid syndrome

OBJECTIVE

To determine whether low molecular weight heparin (LMWH) plus low-dose aspirin (LDA) is comparable in efficacy and safety to unfractionated heparin (UFH) plus LDA in the management of pregnant women with a history of recurrent spontaneous abortion secondary to antiphospholipid syndrome (APS).

METHODS

In a randomized prospective study, 60 women with a history of 3 or more consecutive spontaneous abortions and positive antiphospholipid antibodies were assigned in equal numbers to receive either UFH (5000 units, twice daily) plus LDA, or LMWH (enoxaparin 40 mg, once daily) plus LDA as soon as pregnancy was diagnosed.

RESULTS

Twenty-four women in the LMWH group (80%) and 20 women in the UFH group (66.67%) delivered a viable infant (P = 0.243). There were no significant differences in pregnancy complications or neonatal morbidity between the 2 groups. There were no incidences of excessive bleeding, thrombocytopenia, or osteoporotic fractures in either group.

CONCLUSION

LMWH plus LDA was successfully used as an alternative to UFH plus LDA in the management of recurrent abortion secondary to APS. The results highlight the need for a larger randomized controlled trial to determine whether LMWH plus LDA should be the treatment of choice for recurrent abortion secondary to APS. Clinicaltrials.gov NCT01051778.

Low molecular weight heparin treatment during subsequent pregnancies of women with inherited thrombophilia and previous severe pregnancy complications

OBJECTIVES

The aim of this study was to investigate the effect of low molecular weight heparin (LMWH) on incidence of adverse outcome in women with thrombophilias and previous severe pregnancy complications.

MATERIALS AND METHODS

The study included 116 women with history of severe preeclampsia, fetal growth restriction (FGR)  ≤5th percentile, severe placental abruption and stillbirth  >20 weeks carrying factor V Leiden or prothrombin mutations, or protein S or C deficiency. Eighty-seven women referred to us for follow-up were treated with LMWH starting from weeks 5-15 (study group, A). Twenty-nine non-treated women referred only for delivery in our institution constituted the control group (B).

RESULTS

The incidence of severe pregnancy complications in previous pregnancies was similar in both groups. Following treatment with LMWH, the incidence of severe preeclampsia was 4.6% in group A compared to 21% in group B, p = 0.007. The incidence of FGR was 2.3% in group A compared to 21% in group B, p = 0.03. The incidence of stillbirth or placental abruption was 0% in group A compared to 7% in group B, p = 0.06. The total incidence of adverse outcome was 7% in group A compared to 55% in group B, p = 0.0001.

CONCLUSION

LMWH treatment of women with previous severe pregnancy complications and thrombophilias significantly reduces the rate of recurrence.

Management of subsequent pregnancy after antepartum stillbirth. A review

In literature, there is a paucity of information about the management of the subsequent pregnancy after stillbirth (SB). we undertook a systematic review of the literature focusing on the evidence for antenatal interventions with the potential to prevent SB and we try to summarise the management of the pregnancy subsequent to a SB. The diverse interventions and their efficacy will be reported according to the possible causes and/or conditions associated to the previous SB. Few of the studies reported SB as an outcome and the evidence was frequently conflicting. Several interventions showed clear evidence of impact on SB, including the scrupulous control of blood sugar by using multiple doses of insulin, frequent antenatal foetal monitoring and timing of delivery in diabetic women; the prophylaxis with low dose of aspirin in high-risk women; or serial sonograms for foetal growth, Doppler studies and antepartum foetal testing in women with previous growth restricted foetus. Other interventions instead reduced know risk factors for SB but failed to show statistically significant impact on SB rate. Overall, early access to care, at least three ultrasounds examinations, screening for the main pregnancy-related disorders and timely delivery are the milestone of appropriate antenatal care in women with previous SB.

Anticoagulants to prevent placenta-mediated pregnancy complications: a review of current evidence

PURPOSE OF REVIEW

Placenta-mediated pregnancy complications are relatively common and are associated with significant morbidity and mortality. Although anticoagulants are increasingly being used to prevent these complications, the evidence supporting their use is limited. This article will focus on reviewing the current evidence base for the use of anticoagulants to prevent placenta-mediated pregnancy complications in women with or without identifiable thrombophilia.

RECENT FINDINGS

Controversy exists whether inherited or acquired thrombophilias cause placenta-mediated complications. Small randomized studies with methodological limitations suggest that antepartum anticoagulant prophylaxis will reduce pregnancy loss in women with both acquired and inherited thrombophilia and prior pregnancy loss. There are no published randomized controlled trials examining anticoagulant prophylaxis in thrombophilic women with prior preeclampsia, intrauterine growth restriction or placental abruption. More recently, the benefit of antepartum anticoagulant prophylaxis in women without thrombophilia with prior placenta-mediated pregnancy complications has been suggested in a small pilot randomized trial.

SUMMARY

Overall, although antepartum anticoagulant prophylaxis has the potential to reduce placenta-mediated pregnancy complications in women with and without identifiable thrombophilia, the data generated by these trials are methodologically limited and inadequate. Hence, we conclude that further trials are required prior to adopting the use of antepartum anticoagulant prophylaxis to prevent placenta-mediated pregnancy complications in routine clinical practice.

A retrospective analysis of fondaparinux versus enoxaparin treatment in women with infertility or pregnancy loss

PROBLEM

We compared the pregnancy success rates and safety parameters of fondaparinux versus enoxaparin, combined with immunotherapy, in patients with a history of miscarriage and/or infertility and coagulant defects.

METHOD OF STUDY

A total of 127 pregnancies in 110 patients with a history of miscarriage and/or infertility were retrospectively evaluated. Of these, 29 pregnancies used fondaparinux 2.5 mg daily and 98 pregnancies used enoxaparin 30 mg twice daily.

RESULTS

The pregnancy success rate was 59% (17/29; 95% CI, 41-75%) for patients receiving fondaparinux and 58% (57/98; 95% CI, 48-68%) for patients receiving enoxaparin. No difference was detected in birth weight (2.7 +/- 0.8 and 2.9 +/- 0.6 kg, respectively) or gestational age at delivery (37.3 +/- 2.2 and 37.7 +/- 2.1 weeks, respectively). No birth defects, severe bleeding-related complications, or serious allergic reactions were observed.

CONCLUSION

In patients with a history of miscarriage, infertility, and coagulant defects receiving immunotherapy, fondaparinux resulted in successful pregnancy outcomes comparable with enoxaparin therapy. Although no difference in outcome was observed in our analysis, a much larger study is required to achieve statistical power.