From bench to in silico and backwards: What have we done on genetics of recurrent pregnancy loss and implantation failure and where should we go next?

Human reproduction goes through many challenges to its success and in many cases it fails. Cases of pregnancy loss are common outcomes for pregnancies, and implantation failures (IF) are common in assisted reproduction attempts. Although several risk factors have already been linked to adverse outcomes in reproduction, many cases remain without a definitive cause. Genetics of female reproduction is a field that may bring some pieces of this puzzle; however, there are no well-defined genes that might be related to the risk for recurrent pregnancy loss (RPL) and IF. Here, we present a literature review of the studies of genetic association in RPL and IF carried out in the Brazilian population and complemented with a database search to explore genes previously related to RPL and IF, where a search for genes previously involved in these conditions was performed in OMIM, HuGE, and CTD databases. Finally, we present the next steps for reproductive genetics investigation, through genomic sequencing analyses and discuss future plans in the study of RPL genetics. The combined strategy of looking for literature and databases is useful to raise hypotheses and to identify underexplored genes related to RPL and IF.

Systematic review and meta-analysis of association between plasminogen activator inhibitor-1 4G/5G polymorphism and recurrent pregnancy loss: an update

BACKGROUND

We conducted this systematic review and meta-analysis to better understand the association between rs1799762 PAI-1 gene polymorphism and the risk of RPL.

METHODS

A systematic search for studies that assessed the association between PAI-1 4G/5G polymorphism and RPL risk published in search sources, PubMed/Medline, ISI Web of Knowledge, Scopus, and Google Scholar till January 2024 was conducted.

RESULTS

There were 23 case-control studies in total, with a high degree of statistical heterogeneity among them which indicated the need for subgroup analysis. We found a significant positive association between the risk of RPL and 4G/4G PAI-1 (OR: 2.57; 95% CI: 1.69-3.90), likewise 4G/5G (OR: 2/02 95% CI: 1.39-2.92) and mixed genotype (4G/4G+4G/5G) (OR: 2.31 95% CI: 1.81-2.93). Considering the ethnicity, the 4G/4G polymorphism is significantly associated with Asian descent (OR: 2.10; CI: 1.65-2.69) while the strong association (OR: 6.47; CI: 3.23-12.97) observed in the Greater Middle East descent is not statistically significant (P=0.16). PAI-1 4G/5G polymorphism association with RPL was only significant in Greater Middle East descent (OR: 2.93; CI: 2.41-3.56), and mixed genotype was significantly associated with RPL in Asian (OR: 2.37; CI: 1.55-3.61), Greater Middle East (OR: 3.01; CI: 2.16-4.19), and European populations (OR: 1.38; CI: 0.91-2.10). The association between RPL and PAI-1 4G/4G was significant for RPLs both under 12 weeks (OR: 1.82; 95% CI: 1.34-2.47), and under 24 weeks (OR: 1.46; 95% CI: 1.11-1.92), while considering heterozygote form the association was only significant for RPLs under 24 weeks (OR: 1.91; 95% CI: 1.58-2.31). Regarding the mixed genotype, there is a significant positive association between PAI-1 and RPL for RPLs under 12 weeks (OR: 2.09; 95% CI: 1.49-2.93), and under 24 weeks (OR: 2.10; 95% CI: 1.52-2.92).

CONCLUSIONS

Our findings indicate a significant association between the rs1799762 PAI-1 polymorphism and the risk of RPL.

The relevance of prothrombotic genetic variants in women who experienced pregnancy loss or embryo implantation failure: A retrospective analysis of 1922 cases

OBJECTIVE

The aim of our study was that to assess the allelic and genotype frequencies of nine prothrombotic gene variants in patients with a history of pregnancy loss and recurrent pregnancy loss (RPL). Women who underwent assisted reproductive technology (ART) with ongoing pregnancy and those with recurrent implantation failure (RIF) were also included.

METHODS

Nine prothrombotic gene variants were evaluated: factor V Leiden (FVL), factor V, H1299R variant (FVR2), factor II (FII) G20210A, methylene-tetrahydrofolate reductase (MTHFR) C677T and A1298C, beta-fibrinogen -455G>A, factor XIII (FXIII) V34L, human platelet antigen-1 (HPA-1) L33P variants, and plasminogen activator inhibitor-1 (PAI-1) 4G/5G. The following study groups were assessed: (1) women who experienced one (n = 334) or two (n = 264) episodes of pregnancy loss; (2) 468 women who experienced RPL; (3) 214 women who underwent ART followed by ongoing pregnancies; and (4) 282 women who experienced RIF after ART, that is, three or more consecutive implantation failures following high-quality embryo transfers to the uterus with an appropriate endometrium. As control group, 430 subjects from the general population were enrolled.

RESULTS

FVL, the -455G>A variant of beta-fibrinogen, and PAI-1 4G were associated with a higher risk of developing RPL compared with the general population. Furthermore, FVL, FVR2, FII G20210A and MTHFR C677T conferred a significantly higher risk of RIF in women who performed ART compared with the general population. No statistical differences between the general population and other study groups were observed.

CONCLUSIONS

Specific prothrombotic genetic variants are more frequently expressed in women with RPL and RIF, supporting their role in the development of polimicrothrombosis and impairing the invasion during embryo implantation.

A Retrospective Observational Study Using Administrative Databases to Assess the Risk of Spontaneous Abortions Related to Environmental and Socioeconomic Conditions

Miscarriage is one of the most frequent adverse events that occurs during pregnancy. This retrospective study aimed to verify if the environmental and socioeconomic conditions related to geographical areas where women live, and the socio-demographic and clinical factors play a role in the risk of spontaneous abortion (SA). The analyses were conducted by hospital discharge records (HDRs) from public and private hospitals in Apulia from 1 January 2021 to 31 December 2021. Women with an age over 40 years old had a major risk of SA compared with women under 18 years (OR 2.30, IC95%1.16-4.54). A reduction in the risk of SA was found for women with an endocrinological or metabolic disease (OR 0.28, 95% CI 0.19-0.41), while genetic disease greatly increases the risk (OR 9.63, IC95% 1.98-46.86). The greatest risk of spontaneous abortion was found in the province of Taranto compared to the province of Foggia (OR 2.01, 95% CI 1.52-2.64). The provinces with a higher risk of SA in the multiple comparisons were Taranto, Brindisi, and BAT. Municipalities with socioeconomic disadvantages classified as very low, low, and medium had a higher risk of SA compared to the municipalities with a high disadvantage. In conclusion, our study indicates the possible association between SA rate and environmental conditions. Additionally, the socioeconomic, clinical, and demographic factors were related to the risk of SAs.

Thrombophilic gene polymorphisms and recurrent pregnancy loss: a systematic review and meta-analysis

PURPOSE

Recurrent pregnancy loss (RPL) is affecting 1-4% of women who conceive approximately, and no cause could be found in more than 50% of women suffering from RPL. Inherited thrombophilias have got increasing attention in women with unexplained RPL, so we aim to explore the relationship among these most common thrombophilic polymorphisms and RPL through a literature review and meta-analysis.

METHODS

Observational studies from PubMed, Embase, Cochrane, and Web of Science from 1997 to 7 April 2022 were searched. For each genetic variant, a fixed or random-effect model was used according to the heterogeneity test to calculate pooled ORs and 95% CIs for both dominant and recessive genetic models. Egger's line regression test was used to assess publication bias. The quality of the included articles was assessed by the Newcastle Ottawa scale.

RESULTS

A total of 124 articles comprising 17,278 RPL patients and 16,021 controls were included. Results showed that hyperhomocysteinemia (MTHFR) C677T (dominant model: OR, 1.43; 95% CI, 1.25-1.64; recessive model: OR, 1.60; 95% CI, 1.36-1.87), MTHFR A1298C (dominant model: OR, 1.66; 95% CI, 1.26-2.18; recessive model: OR, 1.79; 95% CI, 1.42-2.26), PAI-1 4G/5G (dominant model: OR, 1.67; 95% CI, 1.36-2.06; recessive model: OR, 1.80; 95% CI, 1.39-2.32), angiotensin-converting enzyme I/D (OR, 1.23; 95% CI, 1.00-1.53), Factor XIII V34L (OR, 1.38; 95% CI, 1.02-1.87), and β-fibrinogen-455G/A (OR, 1.60; 95% CI, 1.02-2.51) were significantly associated with RPL.

CONCLUSION

This study provides potentially useful clinical markers to evaluate the risk of RPL or to help unexplained RPL patients identify possible causes, which may allow for targeted treatment.

Maternal Thrombophilic and Hypofibrinolytic Genetic Variants in Idiopathic Recurrent Pregnancy Loss: a Continuing Mystery

Despite the fact that multiple recurrent pregnancy loss (RPL) etiologies have been identified, 50-70% of RPL cases remain enigmatic, and idiopathic RPL is still a serious medical challenge. A plethora of studies have investigated the correlation of RPL with variations in coagulation and/or fibrinolytic factors-encoding genes. Notwithstanding, evidence for a link between these variations and RPL remains discordant. We aimed to explore the association of thrombophilic and hypofibrinolytic gene variations with RPL development. Two hundred Saudi women were recruited in this study, comprising 150 women experiencing RPL and 50 healthy women. Thirteen genetic variants, including FV G1691A, FV A4070G, F2 G20210A, F13A1 G103T, FGB - 455G > A, PAI-1 - 675 4G/5G, ITGB3 T1565C, MTHFR C677T, MTHFR A1298C, ACE I/D, APOB G10708A, APOE T388C, and APOE C526T were genotyped using ViennaLab StripAssay. Women experiencing RPL harbor significantly higher frequencies of the F13A1 103 T, FGB - 455A, and ITGB3 1565C alleles than control women (p < 0.001). No differences in the prevalence of other investigated variants were identified between control women and those with RPL. No considerable link of F5 1691G > A/4070A > G, MTHFR 677C > T/1298A > C, and APOE 388 T > C/526C > T haplotypes with RPL risk was demonstrated. F13A1 G103T, FGB - 455G > A, and ITGB3 T1565C variants are connected to a higher likelihood of developing RPL and, hence, may have the potential to identify those women at risk of RPL, thereby, improving RPL susceptibility prediction. Incorporating molecular testing of thrombophilic and hypofibrinolytic genetic variants into routine workup could confer a promising approach for refined RPL risk assessment.

Thrombophilia screening in women with recurrent first trimester miscarriage: is it time to stop testing? - a cohort study and systematic review of the literature

OBJECTIVE

There are numerous studies reporting a disproportionally high prevalence of thrombophilia in women with a history of recurrent miscarriage (RM), which has led to overdiagnosis and treatment without an improvement in clinical outcomes. The objective of our study was to assess the prevalence of inherited and acquired thrombophilia in a large cohort of women with a history of early RM using internationally agreed diagnostic criteria and inclusion parameters and compare it to the meta-analysis results of existing literature.

METHODS

DESIGN: Retrospective cohort study and systematic review of literature.

SETTING

This is a retrospective cohort study set-up in two dedicated tertiary centres for women with RM in Southwest London and Surrey. We reviewed all the available literature related to causes of RMs. We ascertained the prevalence of thrombophilia in the study population and compared it with historical and published prevalence in the general population.

PARTICIPANTS

1155 women between 2012 and 2017. All patients had three or more first trimester miscarriages and a full thrombophilia screen.

RESULTS

The overall prevalence of thrombophilia in our study population is 9.2% (106/1155) with 8.1% (94/1155) of cases positive for inherited thrombophilia, which is similar to the general population; Factor V Leiden (4.9%; 57/1155) and prothrombin gene mutation (2.9%; 34/1155) were the most common inherited thrombophilias, while only 1% (12/1155) tested positive for acquired thrombophilia. Persistent positive lupus anticoagulant (LA) was found in 0.5% (6/1155) and persistent positive anticardiolipin (ACL) antibodies with a value ≥40 U/mL was found in 0.5% (6/1155) of patients. Tests for LA/ACL were performed a minimum of 12 weeks apart thus meeting the revised Sapporo criteria for a diagnosis of antiphospholipid syndrome.

CONCLUSION

The findings of our study demonstrate that the prevalence of inherited thrombophilia is similar in women with RM to that in the general population. Similarly, the prevalence of acquired thrombophilia, using the revised Sapporo criteria, in the cohort of RMs is similar to that in the general population. Therefore, we do not recommend investigation or treatment of inherited or acquired thrombophilia in women with RM.

PROSPERO REGISTRATION NUMBER

CRD42020223554.

The Role of Plasminogen Activator Inhibitor Type 1 (PAI-1) in Placenta-Mediated Pregnancy Complications: A Systematic Review

Plasminogen activator inhibitor type 1 (PAI-1) is a main inhibitor of fibrinolysis. The PAI-1 gene (SERPINE1) harbors genetic variants with the potential of modifying plasma levels of PAI-1. A delicate balance exists between the coagulation and fibrinolytic system, and changes in PAI-1 have been suggested to compromise establishment of a successful pregnancy. Therefore, this systematic review investigated the association between genetic variants and/or plasma levels of PAI-1 and placenta-mediated pregnancy complications. An extensive literature search was conducted in PubMed, Embase, and Web of Science on the 29^th of April 2021. All studies underwent quality rating according to The Study Quality Assessment Tools checklist provided by National Heart, Lung and Blood Institute. A total of 71 studies were included, among which 60 studies investigated PAI-1 genotypes and 11 studies measured PAI-1 plasma levels. In 32 out of 59 studies, no association was found between the PAI-1 4G/5G polymorphism (rs1799768) and placenta-mediated pregnancy complications, which was stated as no significant difference in the genotype distribution comparing women with and without placenta-mediated pregnancy complications or no significantly increased odds of placenta-mediated pregnancy complications carrying the 4G/4G or 4G/5G genotype. Eight out of 11 studies reported significantly higher PAI-1 plasma levels in preeclamptic women than in women without preeclampsia. In conclusion, no clear evidence indicates that PAI-1 polymorphisms are associated with placenta-mediated pregnancy complications, and the possible association between high PAI-1 plasma levels and preeclampsia needs further investigations. Thus, investigation of PAI-1 genotypes and PAI-1 plasma levels does not currently seem to have a place in daily clinical practice managing placenta-mediated pregnancy complications.

Hereditary thrombophilia and recurrent pregnancy loss: a systematic review and meta-analysis

STUDY QUESTION

Is there an association between hereditary thrombophilia in pregnant women and risk of recurrent pregnancy loss (RPL)?

SUMMARY ANSWER

Pregnant women with hereditary thrombophilia have an increased risk of RPL, especially for pregnant women with the G1691A mutation of the factor V Leiden (FVL) gene, the G20210A mutation of the prothrombin gene (PGM), and deficiency of protein S (PS).

WHAT IS KNOWN ALREADY

Prior studies have suggested that pregnant women with hereditary thrombophilia have a higher risk of RPL, however, the results are inconsistent; furthermore, a complete overview is missing. This lack of information is an obstacle to the risk assessment of RPL in pregnant women with hereditary thrombophilia. A comprehensive meta-analysis on the relation between hereditary thrombophilia and the risk of RPL is needed.

STUDY DESIGN, SIZE, DURATION

A systematic review and meta-analysis was performed using observational studies published in English before 1 April 2020 to evaluate the relation between hereditary thrombophilia and risk of RPL.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Relevant studies were identified from PubMed, Web of Science, and EMBASE searches and complemented with perusal of bibliographies of retrieved articles. The exposure of interest was hereditary thrombophilia, including FVL mutation, PGM, deficiency of antithrombin (AT), deficiency of protein C (PC), and deficiency of PS. The overall risk estimates were pooled using random effects models. Subgroup and sensitivity analyses were carried out to explore possible sources of heterogeneity and assess the robustness of the results.

MAIN RESULTS AND THE ROLE OF CHANCE

A total of 89 studies involving 30 254 individuals were included. Results showed that women with FVL mutation (odds ratio (OR): 2.44, 95% CI: 1.96-3.03), PGM (OR: 2.08, 95% CI: 1.61-2.68), or deficiency of PS (OR: 3.45, 95% CI: 1.15-10.35) had higher risks of developing RPL. Compared with the reference group, there was no observed relation between a deficiency in AT or PC and RPL (all P > 0.05). Heterogeneity in the risk estimates of RPL was partially explained by geographic region, definitions of RPL, types of RPL, and controlled confounders. Sensitivity analyses validated the robustness of the findings.

LIMITATIONS, REASONS FOR CAUTION

Only 39 of the included studies controlled for one or more confounders, and the heterogeneity across all included studies was high. Based on the data available, we cannot determine whether this association is confounded by other potential risk factors of RPL.

WIDER IMPLICATIONS OF THE FINDINGS

This systematic review and meta-analysis show a possible association between hereditary thrombophilia and an increased risk of RPL, suggesting that testing for hereditary thrombophilia should be considered in individuals with RPL.

STUDY FUNDING/COMPETING INTEREST(S)

The study was funded by the Hunan Provincial Key Research and Development Program (Grant number: 2018SK2062) and National Natural Science Foundation Program (Grant number: 81973137). There are no conflicts of interest.

REGISTRATION NUMBER

N/A.

MTHFR 1298A>C Substitution is a Strong Candidate for Analysis in Recurrent Pregnancy Loss: Evidence from 14,289 Subjects

We undertook meta-analyses on MTHFR 1298A>C substitution for critically evaluating its association with recurrent pregnancy loss (RPL). MTHFR genotype data for 5888 cases and 8401 controls from 39 studies were pooled to perform this meta-analyses. Genotype data were screened, scrutinized, pooled, analysed and subjected to sensitivity analysis to carefully evaluate the association between MTHFR 1298A>C and recurrent pregnancy loss. Genetic associations were sought using dominant, recessive and co-dominant models of genetic testing with odds ratio and 95% Confidence interval (CI) as the effect measures. Further analyses were undertaken by classifying the studies into Caucasian and East Asian sub-groups. Genetic heterogeneity was tested before pooling the data across studies. For assessing publication bias, Egger's intercept test was undertaken. We found a significant association of 1298A>C substitution with increased risk of RPL in the dominant (P=0.000; OR = 1.58; 95% CI =1.25-1.99) as well as recessive (P=0.000; OR = 1.66; 95% CI =1.25-2.20) models. In sub-group analysis, we observed a significant association of the polymorphism with RPL in the Caucasian populations using dominant (P=0.000; OR = 1.98; 95% CI =1.42-2.76) and recessive (P=0.000; OR = 2.20; 95% CI =1.49-3.24) models. However, this substitution showed no association with RPL in the East Asian populations (P=0.149; OR = 1.187; 95% CI =0.94-1.50). MTHFR 1298A>C substitution shows association with the risk of recurrent pregnancy loss. The association is in a population-specific manner with the substitution being a strong risk factor only in the Caucasian populations.

Factor V Leiden 1691G > A mutation and the risk of recurrent pregnancy loss (RPL): systematic review and meta-analysis

Background

Although numerous replication case-control studies have attempted to determine the association between Factor V Leiden (FVL) 1691G > A mutation and susceptibility to Recurrent pregnancy loss (RPL), there have been confliction among the results of various ethnic groups. To address this limitation, here we implemented first meta-analysis to provide with consistent conclusion of the association between FVL 1691G > A mutation and RPL risk.

Methods

After a systematic literature search, pooled odds ratio (OR) and their corresponding 95% confidence interval (CI) were used to evaluate the strength of the association. Additionally, meta-regression analyses were performed to find potential source of heterogeneity.

Results

In this meta-analysis, 62 studies, containing 10,410 cases and 9406 controls, were included in quantitative analysis. Overall population analysis revealed a significant positive association in the dominant (OR = 2.15, 95% CI = 1.84-2.50, P < 0.001), over-dominant (OR = 1.88, 95% CI = 1.61-2.19, P < 0.001), allelic (OR = 2.05, 95% CI = 1.79-2.35, P < 0.001), and heterozygote (OR = 1.97, 95% CI = 1.68-2.30, P < 0.001) models. Moreover, a significant association of dominant (OR = 3.04, 95% CI = 2.04-4.54, P < 0.001), over-dominant (OR = 2.65, 95% CI = 1.74-4.05, P < 0.001), and heterozygote (OR = 2.67, 95% CI = 1.81-4.22, P < 0.001) models was found in the Iranian population. The subgroup analysis indicated strong significant association in Asian, European, Africa population, and case-control studies but not in South Americans and cohort studies.

Conclusion

The FVL 1691G > A mutation and the risk of RPL confers a genetic contributing factor in increasing the risk of RPL, particularly in Iranians, except for South Americans.

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.

Retinal vascular occlusion: a window to diagnosis of familial and acquired thrombophilia and hypofibrinolysis, with important ramifications for pregnancy outcomes

Aim

Our specific aim was to document the pathoetiologic importance of thrombophilia among females presenting with severe ischemic retinal vein (RVO) or retinal artery (RAO) occlusion, without typical risk factors, and to emphasize that the ophthalmologists’ diagnosis of thrombophilia has important diagnostic and therapeutic downstream ramifications for nonocular thrombosis, including reproductive outcomes.

Methods

We evaluated familial and acquired thrombophilia in 60 females with RVO (central RVO, n=52; branch RVO, n=8) and 16 with RAO (central RAO, n=11; branch RAO, n=5). They were referred by retinologists, without typical risk factors for RVO/RAO and/or severe ocular ischemic presentation. We focused on extraocular thrombotic events, particularly pregnancy complications, including unexplained spontaneous abortion, pre-eclampsia–eclampsia. Thrombophilia measurements in the 76 females were compared with 62 healthy normal females without ocular vascular occlusions (OVOs).

Results

The 76 females with OVO were more likely than 62 normal female controls to have high homocysteine (24% vs 0%, P<0.0001), high anticardiolipin antibody (immunoglobulin M, 17% vs 3%, P=0.012), high (>150%) factor VIII (42% vs 11%, P<0.0001), and high (>150%) factor XI (22% vs 4%, P=0.004). Of the 76 females, 26 (34%) had ≥1 spontaneous abortion; 17 (22%) had ≥2 spontaneous abortions and/or pre-eclampsia–eclampsia. Compared to 62 healthy female controls, these 17 females with pregnancy complications had high homocysteine (29% vs 0%, P=0.0003), high anticardiolipin antibody immunoglobulin M (24% vs 3%, P=0.02), high factor VIII (38% vs 11%, P=0.02), and were marginally more likely to be heterozygous for the factor V Leiden mutation (19% vs 3%, P=0.058).

Conclusion

In females lacking typical risk factors for retinal vascular occlusion or severely ischemic presentation, by diagnosing thrombophilia as an etiology for OVO, the ophthalmologist opens a window to family screening and preventive therapy, with particular relevance to pregnancy outcomes and venous thromboembolism.

Meta-analysis of the association between plasminogen activator inhibitor-1 4G/5G polymorphism and recurrent pregnancy loss

Background

The association between plasminogen activator inhibitor-1 (PAI-1) 4G/5G polymorphism and recurrent pregnancy loss (RPL) risk is still contradictory. We thus performed a meta-analysis.

Material/Methods

Relevant studies were searched for in PubMed, Web of Science, Embase, and Cochrane Library. An odds ratio (OR) with a 95% confidence interval (CI) was used to assess the association between PAI-1 4G/5G polymorphism and RPL risk.

Results

A total of 22 studies with 4306 cases and 3076 controls were included in this meta-analysis. We found that PAI-1 4G/5G polymorphism was significantly associated with an increased RPL risk (OR=1.89; 95% CI 1.34–2.67; P=0.0003). In the subgroup analysis by race, PAI-1 4G/5G polymorphism was significantly associated with an increased RPL risk in Caucasians (OR=2.23; 95% CI 1.44–3.46; P=0.0003). However, no significant association was observed in Asians (OR=1.47; 95% CI 0.84–2.59; P=0.18).

Conclusions

In conclusion, this meta-analysis suggests that PAI-1 4G/5G polymorphism might be associated with RPL development in Caucasians.

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.

Thrombophilia-Related Complications in the Treatment of a Left Atrial Appendage Thrombus: A Case Report

Trans-esophageal echocardiography (TEE) revealed a left atrial appendage (LAA) thrombus in an 84-year-old woman with nonvalvular atrial fibrillation not known before our evaluation. In her medical history, there were hypertension, dyslipidemia and a previous pulmonary embolism. She was taking warfarin at time of our evaluation and presented signs and symptoms of heart failure. Together with heart failure treatment, intravenous anticoagulation with unfractionated heparin was initiated. Treatment was complicated by additional right lower limb embolic event and the LAA thrombus remained unchanged. Testing revealed heterozygosity for both the factor V Leiden and the methylenetetrahydrofolate reductase C677T mutations inducing resistance to activated protein C. The patient refused transcatheter closure of the left atrial appendage.