In vitro evidences of heparin's effects on embryo implantation and trophoblast development

Heparin seems to be effective in ameliorating pregnancy outcome in thrombophilic women with previous recurrent pregnancy loss, preeclampsia, intrauterine growth restriction and sudden fetal death. A prophylactic effect of heparin treatment has also been proposed in terms of prevention of adverse pregnancy outcomes recurrence in women with history of recurrent miscarriage, severe preeclampsia, placental abruption, low neonatal birth weight and intrauterine fetal death not related to thrombophilia, although literature in this field is quite controversial. The molecular mechanisms by which heparin might exert its potential therapeutic effects in human reproduction are still not fully understood. In this article we review the current knowledge in this research field, focusing on in vitro evidences of heparin's mechanisms of action in the processes of embryo implantation and trophoblast invasion.     

Pregnancy outcome in patients with a history of recurrent spontaneous miscarriages and documented thrombophilias

The aim of this study was to evaluate the effect of treatment in patients analyzed for recurrent spontaneous miscarriage with a diagnosis of a hereditary thrombophilia, the presence of antiphospholipid and/or autoimmune antibodies, and/or hyperhomocystinemia (HHC) with or without methylenetetrahydrofolate reductase (MTHFR) polymorphisms. In total, 76 women with 2 or more embryonic or fetal losses were analyzed. Of these, 49 (64.4%) women were found to have one or more thrombophilias and/or autoimmune antibodies, and 33 (43.4%) women were found to have a MTHFR polymorphism and/or HHC. Since completion of the recurrent miscarriage analysis, 39 women conceived again. All women with a thrombophilia were treated with low-dose aspirin plus low molecular weight heparin. All women with previously diagnosed HHC and/or MTHFR polymorphisms were treated with folate and vitamin B(6) and B(12) supplementation. In the thrombophilia group, 27 women conceived resulting in 20 successful pregnancies (74.1%) and 7 pregnancy losses (2 trisomy 16, 1 ectopic pregnancy and 4 unexplained miscarriages), i.e. an unexplained pregnancy loss rate of 14.8%. In the HHC/MTHFR group 22 women conceived, resulting in 17 successful pregnancies (77.3%) and 5 pregnancy losses (1 trisomy 16, 1 Turner syndrome and 3 unexplained miscarriages), i.e. an unexplained pregnancy loss rate of 13.6%.     

Recurrent early pregnancy loss and consanguinity

The present authors have studied the possible relationship between recurrent miscarriage and consanguinity in the Qatari population, where the prevalence of first cousin marriage is 47%. The maternal of three or more early pregnancy losses were compared with those of 92 non-consanguineous women from the same population and with the same obstetrical history, matched for maternal age. The retrospective investigation showed no difference in the rate of previous pregnancy loss and maternal disorders, including diabetes, thyroid dysfunction and immunity, abnormal uterine and ovarian anatomy or thrombophilia. There was also no evidence of familial clustering of recurrent miscarriage in both groups. The prospective study showed no difference in the rate of subsequent pregnancy loss and the median gestational age and fetal weight at delivery in ongoing pregnancies. The absence of a relationship between recurrent miscarriage and consanguinity in Qatar could be due to the particular characteristics of the native Qatari population, in which rare recessive genes are uncommon, or overall to the absence of an association between recurrent miscarriage and consanguinity.     

Thrombophilia-associated pregnancy wastage

OBJECTIVE: To critically review the literature regarding inherited thrombophilia and recurrent fetal loss. DESIGN: English-language literature review. PATIENT(S): Women who experienced repeated pregnancy wastage. INTERVENTION(S): Aspirin, glucocorticoids, heparin, and IV immunoglobulin for the prevention of miscarriage. MAIN OUTCOME MEASURE(S): Live birth, miscarriage, preeclampsia, and pregnancy loss. RESULT(S): Recurrent fetal loss and other placental vascular pathologies of pregnancy have long been associated with antiphospholipid syndrome, an acquired autoimmune thrombophilic state. The number of known heritable thrombophilic disorders has grown rapidly in recent years with the identification of activated protein C resistance, factor V Leiden mutation, and hyperhomocysteinemia as major causes of thrombosis. Data accumulated over the past 2 years suggest that heritable thrombophilia is associated with an increased risk of fetal loss and preeclampsia. The present review discusses potential pathogenetic mechanisms for this association and evaluates reported therapeutic regimens for the prevention of fetal loss in women with thrombophilia. CONCLUSION(S): Placental thrombosis may be the final common pathophysiologic pathway in most women with habitual abortions and repeated pregnancy wastage. Prophylactic antithrombotic therapy is indicated in women with heritable thrombophilia and antiphospholipid syndrome and probably is more effective than the previously used modalities of prednisone, aspirin, and IV immunoglobulin.     

血栓前状态与复发性流产及抗凝治疗

摘要：复发性流产是一种常见的妊娠相关疾病，发生率大约1%～3%。目前，妊娠期血栓前状态是复发性流产领域的研究热点。遗传性血栓前状态及获得性血栓前状态都是自然流产的高危因素。抗凝治疗是针对血栓前状态有效的治疗措施，仍需更完善的循证医学证据来证实其对于复发性流产患者的有效性。     

Hereditary thrombophilias are not associated with a decreased live birth rate in women with recurrent miscarriage

OBJECTIVE: To assesses the live birth rate without treatment in women with hereditary thrombophilia who have recurrent miscarriage and women without thrombophilia who have recurrent miscarriage. DESIGN: Prospective observational study. SETTING: Tertiary referral unit in university hospital. PATIENT(S): One hundred twenty women with thrombophilia and 65 women without thrombophilia. MAIN OUTCOME MEASURE(S): Number of live births or repeated miscarriages. RESULTS: Of the 185 patients, 44 with thrombophilia and 26 without thrombophilia have conceived. Nineteen of the 44 pregnancies (43.2%) in thrombophilia patients have terminated in live births, compared with 8 of 26 pregnancies (30.8%) in patients without thrombophilia. This difference is not statistically significant. CONCLUSIONS: Hereditary thrombophilia did not seem to affect the live birth rate in women with recurrent miscarriage.     

Testing for inherited thrombophilia in recurrent miscarriage

Approximately 1-5% of women trying to conceive experience recurrent miscarriage, and in 50% of these women, the cause of the preceding miscarriages is unknown. Inherited thrombophilias such as factor V Leiden mutation, prothrombin gene mutation (PT 20210A), and deficiencies of natural anticoagulants protein C, protein S, and antithrombin are associated with recurrent miscarriage. Knowledge of the association between inherited thrombophilia and recurrent miscarriage and of potential treatment options for improving chances of a live birth could tempt physicians to test for inherited thrombophilia in women with recurrent miscarriage. However, the strength of the association between inherited thrombophilia and recurrent miscarriage is not very strong, and more importantly, no evidence indicates that the use of anticoagulants improves the chance of live birth in these women. With the current state of evidence, testing for inherited thrombophilia should not lead to altered clinical management and therefore, should not be performed routinely in women with recurrent miscarriage but only in the context of scientific studies.     

Factor XII deficiency in women with recurrent miscarriage

Congenital thrombophilia is known to cause significant maternal complications, and possibly has an adverse effect on normal fetal development. The aim of this study was to assess the prevalence of factor XII (FXII) deficiency in women with a history of recurrent miscarriage. Two hundred and forty-one consecutive Japanese women with a history of two or more recurrent miscarriages were prospectively assessed for their etiology by conventional screening methods. Seven women were found to have reduced FXII activity (19. 2-46.1%) and prolonged activated partial thromboplastin time (33. 3-51.3 s). Of these 7 women, 6 had experienced early pregnancy losses, while 1 woman had experienced repeated mid-trimester fetal losses with coincidental gestational thrombocytopenia. In 241 women with a history of recurrent miscarriage, the prevalence of FXII deficiency was 2.9%.     

Clinical approach to recurrent pregnancy loss

Recurrent pregnancy loss is a topic that most trainee obstetricians and gynaecologists are likely to find themselves confronted with on a regular basis during their roles in early pregnancy assessment unit. We examine the current guidelines from the RCOG and ESHRE on the management of this patient group. The investigation and management of recurrent pregnancy loss is subdivided into the areas of first trimester (5–13 weeks) and second trimester (14–24 weeks) pregnancy loss. These two areas have some overlap but generally reveal differing pathophysiology and treatment. The setting of a recurrent miscarriage clinic is the perfect opportunity to optimise patient's underlying medical co-morbidities and encourage a healthy lifestyle to improve obstetric outcomes. It is also essential to offer psychological support to couples who suffer significant mental health problems and to address factors that are known to be associated with recurrent miscarriage. There are exciting developments in treatment since the last RCOG guideline was published and research is ongoing.     

Progesterone for recurrent miscarriage: truth and deceptions

Recurrent miscarriage is known to affect 0.5-2% of pregnant women, and the standard investigative protocol fails to identify a specific cause in 50% of cases. Progesterone, a key hormone in pregnancy maintenance, has been used to support early pregnancy for decades. A growing body of considerable evidence indicates that in addition to women with luteal phase defects, women with idiopathic recurrent miscarriage may benefit from progestogen treatment, as progesterone has been shown to be an essential immunomodulatory agent in early pregnancy. It plays a critical role in the expression, modulation and inhibition of various growth factors, cytokines, cell adhesion molecules and decidual proteins. Some studies have revealed a remarkable improvement in pregnancy outcome after progestogen supplementation in women suffering from recurrent miscarriage. As most studies on this topic are of unsufficient statistical power, further research on the efficacy of progestogen treatment in affected women is required.     

M��tterliche Thrombophilien

The association between maternal thrombophilia and an increased risk of pregnancy -associated thromboembolic events is well established. According to specific thrombophilic disorders, risk-adapted strategies for prevention and treatment are mandatory. Anticoagulation treatment is usually to started after pregnancy has been detectedion. Further consequences of maternal thrombophilic disorders may include complications such as recurrent miscarriage, intrauterine growth restriction reduction and preeclampsia. A sScreening for thrombophilic disorders is advisable for all patients with a positive personal or family history of thromboembolic diseases or recurrent miscarriages, but not generally for all women who desire to become pregnant. Prophylactic anticoagulation is not indicated to improve pregnancy rates in patients undergoing assisted reproduction, whereas current data areis inconsistent regarding whether heparin is beneficial in patients with a history of recurrent miscarriages after an antiphospholipid syndrome hasd been excluded.     

Habitueller Abort – genetische Ursachen

Genetic factors play an etiologic role in sporadic and recurrent miscarriage. Fetal chromosomal anomalies are the main cause of sporadic miscarriages, whereas in recurrent miscarriages, the rate of fetal chromosomal anomalies is inversely correlated to the number of miscarriages. An abnormal karyotype is present in 3–5% of women with a diagnosis of recurrent miscarriage and their partners. Specific polymorphisms are also associated with an increased risk for recurrent miscarriage. Genetic thrombophilia conferred by carrying the factor V Leiden polymorphism is of clinical relevance for women with recurrent miscarriage due to possible treatment with heparin. Another genetic factor associated with recurrent miscarriage is skewed X-chromosome inactivation, defined as a selective inactivation of paternal or maternal X chromosomes. In addition, androgenetic anomalies such as sperm aneuploidy and sperm DNA fragmentation have been described as etiologic factors in recurrent miscarriage.     

Recurrent miscarriage

Recurrent miscarriage is a distinct clinical entity which links the study of both infertility and later pregnancy complications. Whilst several traditionally held beliefs as to the causes and treatments of recurrent miscarriage have not withstood rigorous scrutiny, recent advances have afforded couples an evidence-based approach to their investigation and treatment. The antiphospholipid syndrome has emerged not only as an important and treatable cause for recurrent pregnancy losses at all gestational ages but also opened new avenues of research into the relationship between thrombophilic abnormalities and adverse pregnancy outcomes. The development of newer molecular tools has allowed us to study potential genetic causes of recurrent miscarriage at the subchromosomal level whilst advances in preimplantation genetic diagnosis offer couples with a chromosome translocation a novel form of treatment.     

Is miscarriage a coagulopathy?

PURPOSE OF REVIEW: Pregnancy is a hypercoaguable state. The hypothesis has been developed that many cases of recurrent miscarriage and of later pregnancy complications are caused by a defective maternal haemostatic response leading to thrombosis of the uteroplacental vasculature and subsequent fetal loss. The evidence upon which this hypothesis is based is reviewed. RECENT FINDINGS: The majority of studies report an increased prevalence of genetic thrombophilic mutations in the female partner of couples with recurrent miscarriage. It is important to note, however, that this is not a uniform finding. A sub-group of women with recurrent miscarriage has been demonstrated to be in a prothrombotic state before pregnancy, and that women in such a state are at an increased risk of miscarriage in future untreated pregnancies. Furthermore, the long-term health implications of this hypercoaguability have been highlighted in a large retrospective study reporting an increased risk of ischaemic heart disease among women with a history of pregnancy loss. SUMMARY: Although recurrent miscarriage is a heterogeneous condition and no single abnormality will account for all cases of pregnancy loss, the relationship between abnormalities in the haemostatic pathways and pregnancy outcome is increasingly recognized. The challenges we face are how to discriminate between women with a thrombophilic defect who are destined to miscarry from those whose pregnancy will be successful, the pathology of pregnancy loss associated with thrombophilic defects, the role of the fetal genotype in determining pregnancy outcome, and the management of women with thrombophilic defects both during and beyond their reproductive years.     

Inherited thrombophilia and pregnancy with fetal loss

Maternal thrombophilia (inherited and acquired) has recently been identified as a major cause of thrombembolism (TE), but it may also contribute to adverse pregnancy outcomes and recurrent pregnancy loss. If the acquired thrombophilia is a well-established factor in etiology of fetal loss, the contribution of specific inherited thrombophilic genes is still controversial. The most common inherited traits are deficiency of antithrombin, protein C or protein S; Factor V Leiden; prothrombin G20210A; MTHFR C677T This review focuses on association of recurrent fetal loss with specific gene thrombophilic defects. Overall 52% of women with obstetric complication other than TE carry thrombophilic gene defects. The role of specific genes is different in etiology of early and late pregnancy loss. Inherited thrombophilia is now view as multicausal model; clinical manifestation can be heterogeneous result of gene-gene and gene-environment interactions. Therefore the criteria for genetic screening affected women with history of fetal loss should not be very stringent. The implication of screening for thrombophilic mutations allow to find women at risk of thrombosis and vascular gestational abnormalities in which antithrombotic drugs may have potential therapeutic benefit.     

Sperm DNA fragmentation is a novel biomarker for early pregnancy loss

Research questionSpontaneous pregnancy loss affects 10–15% of couples, with 1–2% suffering recurrent pregnancy loss and 50% of miscarriages remaining unexplained. Male genomic integrity is essential for healthy offspring, meaning sperm DNA quality may be important in maintaining a pregnancy. Does sperm DNA fragmentation measured by alkaline Comet assay act as a biomarker for early pregnancy loss?DesignSperm DNA fragmentation was measured by alkaline Comet test in 76 fertile donors and 217 men whose partners had recently experienced miscarriage. Couples were divided into five groups for analysis: one miscarriage after spontaneous conception; two or more miscarriages after spontaneous conception; one miscarriage after fertility treatment; two or more miscarriages after fertility treatment and biochemical pregnancy.ResultsReceiver operator characteristic curve analysis was used to determine ability of the average Comet score (ACS), low Comet score (LCS) and high Comet score (HCS) to diagnose miscarriage and develop clinical thresholds comparing men whose partners have miscarried with men with recently proven fertility. Male partners of women who had miscarried had higher sperm DNA damage (ACS 33.32 ± 0.57%) than fertile men (ACS 14.87 ± 0.66%; P < 0.001). Average Comet score, HCS and LCS all have promise as being highly predictive of sporadic and recurrent miscarriage using clinical thresholds from comparisons with fertile men's spermatozoa: receiver operating characteristic curve AUC for ACS ≥26%, 0.965; LCS ≤70%, 0.969; HCS ≥2%, 0.883; P <0.0001.ConclusionsSperm DNA damage measured by the alkaline Comet has promise as a robust biomarker for sporadic and recurrent miscarriage after spontaneous or assisted conception, and may provide novel diagnoses and guidance for future fertility pathways.     

Anticoagulant therapy and pregnancy

Low dose aspirin therapy is one of the anticoagulant treatments used during pregnancy. Anticoagulant agents may be useful for several disorders, such as recurrent miscarriage, pre-eclampsia, fetal growth restriction and infertility. However, it is unclear whether anticoagulant therapy can increase the live birth rate in all of these cases. Recent data suggest that a low-dose aspirin and heparin combination therapy is effective in the prevention of recurrent pregnancy loss in women with antiphospholipid syndrome. Thrombogenic diseases, for example, protein C deficiency, protein S deficiency, factor XII deficiency and hyperhomocysteinemia, may cause pregnancy loss. The etiology of recurrent miscarriage is often unclear and may be multifactorial, with much controversy regarding diagnosis and treatment. Although 70% of recurrent pregnancy losses are unexplained, anticoagulant therapy is effective in maintaining pregnancy without antiphospholipid antibody syndrome. We conclude that a low-dose aspirin and heparin combination therapy can be useful for unexplained cases of recurrent pregnancy loss without antiphospholipid antibody syndrome. (Reprod Med Biol 2008; 7 : 1–10)     

Preimplantation genetic diagnosis in early pregnancy loss✰

Miscarriage is a frequent outcome seen in obstetrics with 1 in 5 pregnancies ending in an early pregnancy loss. Aneuploidy is the most significant single factor affecting early pregnancy failure and miscarriage. The risk of aneuploidy increases significantly with increasing maternal age. There has been tremendous advancement in technology that has made preimplantation genetic testing for aneuploidy reliable and accessible. For women in their mid-to-late 30s there is great utility in the use of PGT-A to facilitate single embryo transfer, reduce the risk of clinical miscarriage and ongoing aneuploidy gestations. The current data supports use of preimplantation genetic testing for aneuploidy and single embryo transfer for this population of women. At this time, more prospective data is needed to determine the effect of preimplantation genetic testing for aneuploidy on rates of miscarriage in the recurrent pregnancy loss population.     

Thrombophilia and recurrent pregnancy loss

Many unanswered questions regarding thrombophilia and recurrent pregnancy loss exist. For example, does a true association exist? Are thrombotic mechanisms relevant? Is a second messenger necessary to cause the manifestation of thrombosis? At present it seems that thrombophilia are associated with and may even cause some cases of pregnancy loss. The role of treatment remains to be determined. Although the aim of physicians working in this field is entirely laudable, to allow childless couples to have children, it is necessary to have good evidence of effect before treatment is given to all patients. A serious ethical dilemma remains, however, namely should treatment that may be effective be denied to patients who have prior pregnancy losses? Denial of treatment is extremely distressing for the patient and the physician. The author's own practice is to offer treatment after a full explanation, particularly because treatment is generally prescribed in the antiphospholipid syndrome and justified in hereditary thrombophilias according to the report of Carp and colleagues, showing a 25% improvement in live birth rates in treated patients. When treatment fails, however, the embryo should be karyotyped to exclude chromosomal aberrations.     

Miscarriage history association with euploid embryo transfer outcomes

Research questionIs a history of miscarriage (including recurrent pregnancy loss) associated with euploid cryopreserved embryo transfer outcomes?DesignRetrospective cohort study from 2014 to 2018 of patients at an academic medical centre, undergoing their first cycle of IVF with 24-chromosome Day 5/6 preimplantation genetic testing for aneuploidies (IVF-PGT-A). Multivariate logistic regression was used to investigate the relationship between history of miscarriage and euploid single cryopreserved embryo transfer outcomes (ongoing pregnancy, miscarriage), adjusting for an extensive list of patient and cycle confounders.ResultsIn the study cohort of 283 patients, the overall unadjusted positive beta human chorionic gonadotrophin (bHCG) rate was 70.0%, ongoing pregnancy rate was 52.3%, and the total pregnancy loss (biochemical and clinical pregnancy loss) rate per positive bHCG cycle was 24.7%. While 35.3% of patients had a history of at least one previous miscarriage, 14.5% of patients had a history of recurrent pregnancy loss (RPL). For patients with a history of miscarriage, it was found that the adjusted odds ratios (OR) and 95% confidence intervals (CI) for positive bHCG were 1.30 (0.51–3.27), for ongoing pregnancy were 0.88 (0.38–2.03) and for total pregnancy loss were 1.41 (0.49–4.05), when compared with patients without a history of miscarriage. For RPL patients, OR for positive bHCG, ongoing pregnancy and total pregnancy loss also did not significantly differ when compared with patients with no history of miscarriage.ConclusionsIn this cohort, there was no significant association between miscarriage history and euploid cryopreserved embryo transfer outcomes (ongoing pregnancy, total pregnancy loss) after adjustment for potential confounders. Further study in larger data sets is warranted.