A possible role for activated protein C resistance in patients with first and second trimester pregnancy failure

Activated protein C resistance impact on Syrian candidates for in vitro fertilisation and the benefit of anticoagulation therapy: a retrospective cohort study

Activated protein C resistance (APCR) is a common thrombophilia, caused mainly by a mutation. The impact of APCR on the efficacy of In Vitro Fertilization (IVF) are still unclear, and no solid recommendations for its management were published. To investigate the effect of APCR on IVF outcomes and assess the efficacy of our management protocol, we retrospectively scanned the medical records of women who were tested with APCR assay in 2019 at our fertility centre. The 66 women (12%) positive for APCR had lower odds of reaching clinical pregnancies after IVF 0.18 [95% CI: 0.07-0.47] and fewer live births. The administration of low-molecular-weight heparin and aspirin associated with more implantation in treated compared to untreated APCR-positive women with an odds ratio of 43.2 [7.51-248.6]. In conclusion, APCR negatively affects the number of clinical pregnancies after IVF, but anticoagulation therapy can mitigate this effect and significantly increase clinical pregnancies.Impact StatementWhat is already known on this subject? The evidence about the impact of APCR on IVF outcomes is still inconclusive. According to the Canadian guideline, routine screening for thrombophilia in patients with recurrent pregnancy loss is not recommended. No clear recommendations regarding the management of APCR in the planning for IVF are yet available.What do the results of this study add? APCR significantly increases implantation failure among infertile women who conduct IVF. Management of APCR using LMWH and aspirin was effective in mitigating this effect and increasing successful implantation.What are the implications of these findings for clinical practice and/or further research? Our findings can support the recommendation to include APCR assay in the routine tests for infertile women conducting IVF, and suggest the combination between LMWH and aspirin as an effective therapy to increase successful implantation in APCR positive candidates. However, more controlled clinical trials are still needed to confirm our results.

Predictive value of thromboelastography parameters combined with antithrombin III and D-Dimer in patients with recurrent spontaneous abortion

PROBLEM

To investigate the value of thromboelastography (TEG) combined with antithrombin III (AT-III) and D-Dimer in predicting the occurrence of recurrent spontaneous abortion (RSA).

METHOD OF STUDY

One hundred and five RSA patients and 40 fertile women were enrolled. The subjects were subjected into four groups: group 1 (40 fertile women), group 2 (58 women with 2 abortions), group 3 (30 women with 3 abortions), and group 4 (17 women with four abortions). TEG was conducted on all subjects. Clotting time, reaction time, angle degree, coagulation index, and maximum amplitude were measured. The levels AT-III, D-Dimer, platelet counts, and fibrinogen concentration were determined. The ROC curve analysis was done using MedCalc software to analyse the diagnosis accuracy of the parameters of interest and the combined approach.

RESULTS

The AT-III level in all group 4 was significantly lower than in fertile women. The D-Dimer concentration, platelet count, and MA in patients with four prior abortions were significantly higher than the other three groups. CI and fibrinogen concentration in patients with four prior pregnancy losses were significantly higher than group 1. The ROC curves suggested that combined use of CI, MA, AT-III, and D-Dimer was with the highest accuracy 92.8%, thus predicting the most accurate diagnosis for RSA.

CONCLUSION

Recurrent spontaneous abortion is associated with abnormal coagulation and anticoagulation. TEG combined with detection of AT-III and D-Dimer levels can distinguish patient with RSA from those with normal fertility and highly possibly predict the occurrence of RSA.

Inherited Thrombophilias Could Influence the Reproductive Outcome in Women with Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease associated with different reproductive complications in the affected women. Inherited thrombophilias are genetic factors increasing the risk for thromboembolism and recurrent pregnancy loss, but their influence on other reproductive disturbances in SLE patients has not been completely clarified. Two hundred and twenty-three Caucasian women (112 with SLE and 111 controls) were included in the study. Complete reproductive history of all SLE patients was carefully obtained. Genotyping for the FV_Leiden, FII_G20210A, and MTHFR_C677T polymorphisms was performed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis. No significant differences in the prevalence of the FV_Leiden, FII_G20210A, and MTHFR_C677T polymorphisms between patients and controls were established. Patients with FV_Leiden had fewer pregnancies (0.57 ± 0.98 vs. 2.18 ± 1.58; p = 0.007) than the others, while no significant differences in the reproductive history of FII_G20210A carriers and non-carriers were observed (p >0.05). In the SLE group, 41.67% of women with the MTHFR_C677T TT genotype had at least one miscarriage in comparison to only 14.00% of the other female patients (p = 0.030). While the prevalence of the investigated thrombophilias was similar in patients with SLE and healthy women, a substantial influence of the inherited prothrombotic factors on the reproductive history of patients was revealed. The investigations of the FV_Leiden and MTHFR_C677T polymorphisms in SLE patients could help to identify women at highest risk for reproductive failure and thus, further studies in other ethnic groups would be of strong clinical importance.

Recurrent Miscarriage Syndrome and Infertility Due to Blood Coagulation Protein/Platelet Defects: A Review and Update

Three-hundred fifty-one women were referred for thrombosis and hemostasis evaluation after suffering recurrent miscarriages. All patients were referred by a high-risk obstetrician or reproductive medicine specialist after anatomic, hormonal or chromosomal defects had been ruled out. These patients were assessed over a three year period. The mean patient age at referral was 34 years and the mean number of miscarriages was 2.9 (2-9). All patients underwent a thorough evaluation for thrombophilia and, when indicated, a hemorrhagic disorder. Of the 351 patients, 29 (8%) had no defect. Of the remaining 322 patients, 7 (2%) had a bleeding disorder: 3 with platelet dysfunction, 1 with Factor XIII deficiency, 3 with von Willebrand’s and 3 with Osler-Weber-Rendu. The remainder of the patients had a thrombophilia as follows: 195 (60%) had antiphospholipid syndrome, 64 (20%) had Sticky Platelet Syndrome, 38 (12%) had MTHFR mutation, 23 (7.1%) had PAI-1 polymorphism, 12 (3.7%) had Protein S deficiency, 12 (3.7%) had Factor V Leiden, 3 (1%), had AT deficiency, 3 (1%) had Heparin-Cofactor II deficiency, 3 (1%) had TPA deficiency, and 6 (2%) had Protein C deficiency. There were a total of 364 defects found in the 312 patients harboring thrombophilia; thus, several harbored two and a few harbored three separate defects. All patients with thrombophilia were treated with preconception ASA at 81 mg/day with the immediate post-conception addition of heparin or LMW heparin (Dalteparin). Both ASA and heparin/LMW heparin were used to term. The first 120 patients were treated with unfractionated heparin at 5,000 U every 24 hours, subcutaneously and the last 192 have been treated with Dalteparin at 5,000 U/day subcutaneously. The patients with MTHFR were also treated with folate at 5 mg/day + pyridoxine at 50 mg/day. All patients were carefully monitored with CBC and platelet counts, anti-Xa levels, frequent ultrasounds and physical exams. Only 2 of the thrombophilia patients suffered another miscarriage; all others had a normal term delivery. There were no pregnancy-related thromboses, no delivery complications and no episodes of post-partum thrombosis. The only bleeding consisted of 1-4 cm bruises at injection sites. No episodes of thrombocytopenia (HIT) were noted. In our experience, thrombophilia is a common cause of recurrent miscarriage and all patients with no anatomical, hormonal or chromosomal defect should be evaluated for thrombophilia or a bleeding disorder. The success rate of normal term delivery in these 312 patients was 94% using ASA + heparin or Dalteparin. In addition, side effects of therapy were minimal.

Prevalence and role of antithrombin III, protein C and protein S deficiencies and activated protein C resistance in Kosovo women with recurrent pregnancy loss during the first trimester of pregnancy

CONTEXT

Several studies have reported that thrombophilia is responsible for recurrent pregnancy loss (RPL).

AIMS

The aim of this study was to evaluate the prevalence and role of inherited thrombophilia in early pregnancy loss, specifically in the first trimester.

MATERIALS AND METHODS

A total of 104 women (patients) with a history of two or more miscarriages during the first trimester of pregnancy and 110 women (controls) who had experienced two or more births without a miscarriage were included in this study. In both groups, we determined the biological activities of antithrombin III (ATIII) and protein C (PC) using the chromogenic method and the biological activity of protein S (PS) and the activated protein C resistance (APCR) were examined using a clotting method.

RESULTS

In the patient group, deficiencies of ATIII, PC, and PS were detected in 3 (2.88%), 4 (3.85%), and 6 (5.77%) cases, respectively. In the control group, ATIII (0%) deficiencies were not detected, and deficiencies for PC (0.9%) and PS (0.9%) were each detected in 1 patient. APCR was detected in 9 patients (8.65%) and 4 control subjects (3.63%).

CONCLUSION

Based on our results, we can conclude that thrombophilia is a causal factor for miscarriages in the first trimester of pregnancy, although there are the conflicting data in the literature.

Factors contributing to APC-resistance in women with recurrent spontaneous miscarriages: Indian perspective

Phenotypic resistance to APC is a complex mechanism associated with increased risk of venous thrombosis in women with recurrent spontaneous abortions. The primary aim of this prospective case control study was to find out the frequencies of different congenital and acquired thrombophilic factors predisposing to APC resistance and to evaluate the strength of their association with recurrent pregnancy losses. FV Leiden accounted for around 40% of all APCR positive patients and the difference in the group frequencies compared with controls, was found to be statistically significant (p=0.001). 18.33% (11/60) FV Leiden-negative APC-resistant patients had

FVIII

c values exceeding 95th percentile of the control population (145IU/dL), as compared to 3% in the control group (p=0.001). Mean FVIII level in control subjects was 118±14.0IUdL(-), compared with 127.7±31.2IUdL(-) in the patient group (p=0.009). Apart from FVIII, only the anti-phospholipid antibodies showed a statistically significant association with APCR phenotype (p=0.028), unlike other thrombophilic factors such as Protein C, Protein S, FV levels, HR2 haplotype or other rarer FV variants. The strong positive association of FVL mutation, anti-phospholipid antibodies and elevated FVIII levels with APCR phenotype calls for incorporating them as first line investigations in patients with recurrent spontaneous miscarriages with APCR positivity.

Factor V Leiden thrombophilia

Factor V Leiden is a genetic disorder characterized by a poor anticoagulant response to activated Protein C and an increased risk for venous thromboembolism. Deep venous thrombosis and pulmonary embolism are the most common manifestations, but thrombosis in unusual locations also occurs. The current evidence suggests that the mutation has at most a modest effect on recurrence risk after initial treatment of a first venous thromboembolism. Factor V Leiden is also associated with a 2- to 3-fold increased relative risk for pregnancy loss and possibly other obstetric complications, although the probability of a successful pregnancy outcome is high. The clinical expression of Factor V Leiden is influenced by the number of Factor V Leiden alleles, coexisting genetic and acquired thrombophilic disorders, and circumstantial risk factors. Diagnosis requires the activated Protein C resistance assay (a coagulation screening test) or DNA analysis of the F5 gene, which encodes the Factor V protein. The first acute thrombosis is treated according to standard guidelines. Decisions regarding the optimal duration of anticoagulation are based on an individualized assessment of the risks for venous thromboembolism recurrence and anticoagulant-related bleeding. In the absence of a history of thrombosis, long-term anticoagulation is not routinely recommended for asymptomatic Factor V Leiden heterozygotes, although prophylactic anticoagulation may be considered in high-risk clinical settings. In the absence of evidence that early diagnosis reduces morbidity or mortality, decisions regarding testing at-risk family members should be made on an individual basis.

Can Factor V Leiden and prothrombin G20210A testing in women with recurrent pregnancy loss result in improved pregnancy outcomes?: Results from a targeted evidence-based review

Women with recurrent pregnancy loss are offered Factor V Leiden (F5) and/or prothrombin G20210A (F2) testing to identify candidates for anticoagulation to improve outcomes. A systematic literature review was performed to estimate test performance, effect sizes, and treatment effectiveness. Electronic searches were performed through April 2011, with review of references from included articles. English-language studies addressed analytic validity, clinical validity, and/or clinical utility and satisfied predefined inclusion criteria. Adequate evidence showed high analytic sensitivity and specificity for F5 and F2 testing. Evidence for clinical validity was adequate. The summary odds ratio for association of recurrent pregnancy loss with F5 in case-controlled studies was 2.02 (95% confidence interval, 1.60-2.55), with moderate heterogeneity and suggestion of publication bias. Longitudinal studies in women with recurrent pregnancy loss or unselected cohorts showed F5 carriers were more likely to have a subsequent loss than noncarriers (odds ratios: 1.93 and 2.03, respectively). Results for F2 testing were similar. For clinical utility, evidence was adequate that anticoagulation treatments were ineffective (except in antiphospholipid antibody syndrome) and had treatment-associated harms. The certainty of evidence is moderate (high, moderate, and low) that anticoagulation of women with recurrent pregnancy loss and F5/F2 variants would currently lead to net harms.

A possible role for familial thrombophilia in women with polycystic ovarian syndrome

PURPOSE

The aim of this study is to evaluate familial thrombophilia factors in infertile patients with polycystic ovarian syndrome (PCOS).

MATERIALS AND METHODS

This analytic study was performed on 123 infertile women with PCOS as the case group, and 73 infertile women with male factor as the control group, who were under treatment. Blood samples were taken on the third day of the menstrual cycle for evaluation of protein S, protein C, antithrombin III, APC-resistance, homocysteine levels and additional metabolic and endocrine parameters for both groups. Comparisons between groups were performed by the t-test, and Fisher exact test. p<0.05 was accepted as statistically significant.

RESULTS

Although the mean value of protein S and protein C in the case group was lower than the control group, there was no significance difference (p=0.752 and p=0.602, respectively). The mean of antithrombin III, activated protein C resistance (APC-R) and homocysteine levels in the two groups were not significant (p=0.756, p=0.603 and p=0.157, respectively).

CONCLUSIONS

We were unable to determine a positive relationship between PCOS and thrombophilia. The existence of a possible trend towards high prevalence of thrombophilia in women with PCOS needs further research.

Recurrent pregnancy loss and thrombophilia

Emerging data seem to be available also on the role of active thromboprophylaxis with heparin and pregnancy outcome. In the last decades we found many data concerning the association between a hypercoagulable state and its causes and adverse pregnancy outcome, in particular recurrent pregnancy loss (RPL). First studies which focused on the association between thrombophilia and RPL underlined the role of reduced clotting inhibitors and RPL, and subsequent studies underlined a pathogenetic role of gene variant associated to hypercoagulable state in the occurrence of RPL. On the other hand, acquired thrombophilic abnormalities as antiphipsholipid syndrome are a well known cause of RPL and should be considered for a screening. These data are relevant because recent studies suggested a role of an extensive thromprophilaxis in women with RPL that should be addressed only in case of known thrombophilia and high risk of venous thromboembolism.

Factor V Leiden mutation: a treatable etiology for sporadic and recurrent pregnancy loss

OBJECTIVE

We hypothesized that the thrombophilic G1691A factor V Leiden (FVL) gene mutation was a common, significant, and treatable cause of sporadic and recurrent pregnancy loss (RPL).

DESIGN

We compared the frequency of the FVL mutation in 141 women with >or=1 pregnancy and 1 sporadic pregnancy loss (308 live births, 141 pregnancy losses), 44 women with >or=1 pregnancy and >or=3 pregnancy losses (105 live births, 180 pregnancy losses), and 638 women with >or=1 live birth pregnancy and 0 pregnancy loss (1553 live births).

SETTING

Outpatient Clinical Research Center.

PATIENT(S)

A total of 823 caucasian women with consecutive measures of the FVL mutation.

MAIN OUTCOME MEASURE(S)

We used polymerase chain reaction techniques to characterize the thrombophilic FVL G1691A gene mutation.

RESULT(S)

Of the 638 controls, 47 (7.4%) had FVL heterozygosity versus 16 heterozygous and 2 homozygous FVL cases (18/141, 12.8%) in 141 women with 1 sporadic pregnancy loss versus 9/44 RPL cases (20.5%, 8 heterozygous and 1 homozygous FVL). The FVL frequency in cases with 1 sporadic pregnancy loss (18/141, 12.8%) did not differ from RPL cases (9/44, 20.45%).

CONCLUSION(S)

After unexplained sporadic pregnancy loss, as well as after RPL, to provide the option to prospectively optimize subsequent live birth outcomes with low-molecular-weight heparin thromboprophylaxis, we suggest that measurements be done of the FVL mutation, a treatable etiology for sporadic pregnancy loss as well as for RPL.

Thrombophilia and adverse pregnancy outcome

This article focuses on the clinical evaluation and management of women who have thrombophilia-related placental vascular complications, including fetal loss, pre-eclampsia, intrauterine fetal growth restriction, and placental abruption. All are major causes of maternal and fetal adverse outcomes.

Inherited Thrombophilia: Key Points for Genetic Counseling

With the evolution of medical genetics to focus on highly prevalent, multifactorial conditions, it is inevitable that genetic counselors will be called upon to participate in the evaluation and counseling of individuals with inherited thrombophilia. The purpose of this review is to educate the genetic counselor on key issues related to risk assessment and genetic counseling for hereditary thrombophilia. The information contained in this document is derived from an extensive review of the literature, as well as the author's personal expertise. Upon completion of this review, the genetic counselor will be able to: a) describe inherited and acquired risk factors for thrombosis, b) collect and interpret personal and family histories to assess risk related to hereditary thrombophilia, c) discuss the potential advantages and disadvantages of thrombophilia testing, including psychosocial aspects and implications for medical management, and d) identify educational and support resources for patients and families.

Thrombophilia and Adverse Pregnancy Outcome

This article focuses on the clinical evaluation and management of women who have thrombophilia-related placental vascular complications, including fetal loss, pre-eclampsia, intrauterine fetal growth restriction, and placental abruption. All are major causes of maternal and fetal adverse outcomes.

Internal Jugular Vein Thrombosis following Mild Ovarian Hyperstimulation Syndrome in Women with Factor V Leiden Mutation

OBJECTIVE

To study two women who presented with internal jugular vein thrombosis that developed shortly after in vitro fertilization (IVF) therapy complicated by mild ovarian hyperstimulation syndrome (OHSS).

METHODS

Evaluation of the past medical history, treatment, laboratory studies, and clinical outcome of both patients.

RESULTS

The two patients were found to be carriers for factor V Leiden mutation (FVLM). One was homozygote and the other heterozygote for that mutation. The genetic predisposition probably contributed to the development of an early thrombosis in these patients despite the mildness of their OHSS. In the homozygote patient, the dose of low molecular weight heparin was reduced due to vaginal bleeding. Afterwards, fetal loss due to an extensive placental infarction occurred. Infarction was confined to maternal side while the fetal side vessels were spared.

CONCLUSION

We suggest that women of European descent, especially those with personal or familial history of thromboembolic events, should be screened for FVLM before IVF treatment. In those found to be carriers of FVLM, preventive anticoagulation should be considered.

A randomized study of thromboprophylaxis in women with unexplained consecutive recurrent miscarriages

OBJECTIVE

To compare the effect of aspirin and enoxaparin on live births in women with unexplained recurrent miscarriages, as well as secondary outcomes including birth weight, uterine and umbilical blood flows, and congenital malformations.

DESIGN

Multicenter randomized comparative cohort study.

SETTING

Four centers including two university hospitals, a peripheral general hospital, and a community health clinic.

PATIENT(S)

One hundred seven patients were randomized, 104 were available for analysis; 54 were randomized to enoxaparin and 50 to aspirin.

INTERVENTION(S)

Treatment with enoxaparin or aspirin in subsequent pregnancy.

MAIN OUTCOME MEASURE(S)

Subsequent live births or miscarriage, and the incidence of obstetric complications.

RESULT(S)

Both groups had a similar live birth rate (relative risk = 0.92, 95% confidence interval: 0.58-1.46). In primary aborters, live births occurred in 17 of 18 (94%) enoxaparin-treated pregnancies compared to 18 of 22 (81%) aspirin-treated pregnancies. In the aspirin group, two pregnancies were terminated: for tricuspid insufficiency and for hemolysis, elevated liver enzymes, low platelet (HELLP) syndrome. One enoxaparin-treated infant was growth restricted (2,020 g) at 36 weeks. Preeclampsia was found in three aspirin-treated patients. Preterm delivery, placental Doppler blood flow, apgar scores, and mean birth weights were similar in both groups. In the aspirin group, one infant underwent orchidectomy after testicular torsion in utero, and one infant had hypoglycemia and convulsions.

CONCLUSION(S)

Both regimens were associated with a high live birth rate and few late pregnancy complications.

Evaluation of natural coagulation inhibitor levels in various hypertensive states of pregnancy

OBJECTIVE

To evaluate the role of natural coagulation inhibitors in various classifications of pregnancy associated hypertension in Turkish population living in Trakya region of Turkey.

STUDY DESIGN

Serum uric acid levels, plasma protein C (PC), protein S (PS), antithrombin III (AT III) activities and activated protein C resistance (APCR) were measured in 80 pregnant women with hypertension (preeclampsia, n = 32; severe preeclampsia, n = 25; eclampsia, n = 14; chronic hypertension, n = 9) and 58 healthy pregnant women. Tukey and Tamhane multiple comparison tests, Kruskal-Wallis, chi2 and Fisher's exact tests were performed for comparison of means and/or medians.

RESULTS

Serum uric acid levels were significantly elevated in women with preeclampsia and severe preeclampsia, but PS activity decreased in women with severe preeclampsia (33.2 +/- 18.9% versus 50.4 +/- 22.7%, p = 0.015) and chronic hypertension (29.5 +/- 14.5% versus 50.4+ /- 22.7%, p = 0.045) compared to healthy controls. There was no significant difference in APCR, and PC or AT III activity between the groups. Platelet counts were significantly lower in women with severe preeclampsia, compared to controls and women with chronic hypertension.

CONCLUSION(S)

Serum uric acid levels and plasma protein S activity may be useful as indices of severity of pathology in pregnancy associated hypertension.

Thrombophilia in pregnancy: a systematic review

Growing evidence suggests that thrombophilia is associated with venous thromboembolism (VTE) and adverse pregnancy outcomes. However, methodological limitations have made it difficult to obtain a clear overview of the overall risks. We conducted a systematic review to determine the risk of VTE and adverse pregnancy outcomes associated with thrombophilia in pregnancy. The effectiveness of prophylactic interventions during pregnancy was also evaluated. Major electronic databases were searched, relevant data abstracted and study quality assessed by two independent reviewers. Odds ratios (ORs) stratified by thrombophilia type were calculated for each outcome. A total of 79 studies were included in our review. The risks for individual thrombophilic defects were determined for VTE (ORs, 0.74-34.40); early pregnancy loss (ORs, 1.40-6.25); late pregnancy loss (ORs, 1.31-20.09); pre-eclampsia (ORs, 1.37-3.49); placental abruption (ORs, 1.42-7.71) and intrauterine growth restriction (ORs, 1.24-2.92). Low-dose aspirin plus heparin was the most effective in preventing pregnancy loss in thrombophilic women (OR, 1.62). Our findings confirm that women with thrombophilia are at risk of developing VTE and complications in pregnancy. However, despite the increase in relative risk, the absolute risk of VTE and adverse outcomes remains low. There is also a lack of controlled trials of antithrombotic intervention to prevent pregnancy complications. Thus, at present, universal screening for thrombophilia in pregnancy cannot be justified clinically.

The factor V Leiden mutation, high factor VIII, and high plasminogen activator inhibitor activity: etiologies for sporadic miscarriage

We hypothesized that the thrombophilic G1691A factor V Leiden gene mutation was a common significant cause of sporadic first trimester miscarriage. We compared thrombophilia and hypofibrinolysis in 92 women (85 white, 5 black, 2 other) with 1 or more pregnancies and 1 miscarriage (143 live births, 92 miscarriages) (cases) and in 380 female controls (355 white, 21 black, 4 other) with 1 or more pregnancies and 0 miscarriages (964 live births). We used polymerase chain reaction techniques to characterize thrombophilic gene mutations (G1691A V Leiden [FV], G20210A prothrombin, C677T/A1298C MTHFR) and hypofibrinolytic gene mutations (plasminogen activator inhibitor [PAI-1] activity 4G4G). We carried out serologic measures of thrombophilia (homocysteine, anticardiolipin antibodies [ACLA] immunoglobulin G and immunoglobulin M, lupus anticoagulant, factor VIII, factor XI, protein C, total and free protein S, antithrombin III) and hypofibrinolysis (plasminogen activator inhibitor activity [PAI-Fx], lipoprotein[a]). Of the 380 controls, 6 (1.6%) had FV heterozygosity vs 12 heterozygous and 2 homozygous FV cases (15.2% [14/92]; P < .0001). Plasminogen activator inhibitor activity was high (> or =21.1 U/mL) in 21 (33%) of 63 cases vs 27 (18%) of 152 controls (P = .013). Factor VIII was high (>150%) in 15 (31%) of 48 cases vs 19 (18%) of 103 controls (P = .079). By logistic regression, with age and factor VIII (categorical [< or =150%, >150%]) as explanatory variables and group (cases, controls) as the dependent variable, after adjusting for age, high factor VIII was a significant predictor for miscarriage (odds ratio, 3.28; 95% confidence interval, 1.34-8.04; P = .01). There were no other group differences (P > .05) in measures of thrombophilia and hypofibrinolysis. After unexplained sporadic first trimester miscarriage, we suggest that measurements be done of the FV mutation, PAI-Fx, and factor VIII, etiologies for sporadic miscarriage.

Inherited thrombophilias and adverse pregnancy outcome: screening and management

Inherited thrombophilias are a heterogenous group of conditions which have been implicated in a variety of pregnancy complications. Evidence is mounting that implicates these inherited disorders in a range of pregnancy outcomes, including recurrent miscarriage, late fetal loss, preeclampsia, abruptio placentae, and intrauterine growth restriction. The most commonly identified inherited thrombophilias consist of Factor V Leiden and the prothrombin gene mutation G20210A. Rarer inherited thrombophilic conditions include deficiencies of protein S, C and antithrombin. More recently, deficiency of protein Z has been linked to pregnancy complications, including preterm delivery. Clinical manifestations often are associated with the presence of more than one inherited thrombophilia, consistent with their multigenic nature. Some, but not all, studies investigating the use of heparin to prevent adverse pregnancy outcome have demonstrated a benefit. However, an adequate randomized trial is required to definitively determine whether heparin anticoagulation is the best prevention option in patients who harbor one or more inherited thrombophilias and are at risk for adverse pregnancy outcome. This review will summarize the association of thrombophilic conditions and obstetrical complications.

Evidence-based care of recurrent miscarriage

Between 0.5 and 1.0% of couples experience recurrent pregnancy loss (RPL), which is defined as three or more consecutive miscarriages. Losses are classified as pre-embryonic (<5 weeks), embryonic (5-10 weeks) or fetal (>10 weeks). Genetic abnormalities are responsible for RPL in 2-4% of these couples. Inadequate progesterone production has been proposed a cause of RPL and progesterone is given to prevent miscarriage, despite a lack of supportive evidence. The factor V Leiden and prothrombin G20210A mutations are common inherited thrombophilias also associated with RPL. Antenatal thromboprophylaxis is sometimes recommended although no data exist regarding efficacy. Antiphospholipid syndrome is known to cause RPL and antenatal thromboprophylaxis reduces the risk of miscarriage. Uterine abnormalities might also result in RPL. About 50% of cases of RPL have no identifiable cause. Alloimmune incompatibility has been proposed as a cause for RPL in these women. The concept of alloimmune-related RPL has not been scientifically validated.

Screening and management of inherited thrombophilias in the setting of adverse pregnancy outcome

Inherited thrombophilic conditions are associated with adverse pregnancy outcomes, including severe pre-eclampsia, fetal loss, abruptio placentae, and intauterine growth restriction. Although the prevalence of these complications is approximately 8% in the general population, their presence is associated with a significantly increased recurrence risk. Thrombophilic conditions most strongly associated with adverse pregnancy outcome include factor V Leiden, prothrombin gene mutation, and deficiencies of protein S, protein C, and antithrombin. Other thrombophilic conditions, such as protein Z deficiency, also appear to be associated with an increased risk of pregnancy complications. Antenatal administration of heparin to prevent pregnancy complications has shown promise in small studies, but a randomized, placebo-controlled trial is necessary to determine whether heparin administration is beneficial in preventing adverse pregnancy outcome.

Thrombophilia and pregnancy complications

OBJECTIVE

This systematic review examines the strength of the association between thrombophilia and recurrent pregnancy loss and other serious obstetric complications. Study design Electronic databases and manual bibliography searches were used to identify studies evaluating the association between thrombophilia and pregnancy loss, preeclampsia, fetal growth retardation, and placental abruption.

RESULTS

Thrombophilic disorders are associated with an increased risk of fetal loss in the majority of case control and cohort studies. The risk is increased throughout pregnancy, but may be higher in the second and third trimester. The common pathologic finding of placental infarction suggests unexplained fetal loss may result from uteroplacental insufficiency and thrombosis. Thrombophilic disorders are not consistently associated with preeclampsia, fetal growth retardation, or placental abruption. Preliminary data suggest prophylactic anticoagulation may improve outcome in thrombophilic women with unexplained recurrent fetal loss.

CONCLUSION

Women with thrombophilia have an increased risk of pregnancy loss and possibly other serious obstetric complications, although definition of the magnitude of risk will require prospective longitudinal studies. Preliminary data suggesting prophylactic anticoagulation may improve gestational outcome provide a rationale for prospective randomized trials in thrombophilic women with unexplained recurrent fetal loss.

Hereditary thrombophilia and fetal loss: a prospective follow-up study

BACKGROUND

As the placental vessels are dependent on the normal balance of procoagulant and anticoagulant mechanisms, inherited thrombophilia may be associated with fetal loss.

OBJECTIVES

We performed a prospective study to investigate the relation between inherited thrombophilia and fetal loss, and the influence of thromboprophylaxis on pregnancy outcome.

PATIENTS AND METHODS

Women were enrolled in the European Prospective Cohort on Thrombophilia (EPCOT). These included women with factor (F)V Leiden or a deficiency of antithrombin, protein C or protein S. Controls were partners or acquaintances of thrombophilic individuals. A total of 191 women (131 with thrombophilia, 60 controls) had a pregnancy outcome during prospective follow-up. Risk of fetal loss and effect of thromboprophylaxis were estimated by frequency calculation and Cox regression modelling.

RESULTS

The risk of fetal loss appeared slightly increased in women with thrombophilia without a previous history of fetal loss who did not use any anticoagulants during pregnancy (7/39 vs. 7/51; relative risk 1.4; 95% confidence interval 0.4, 4.7). Per type of defect the relative risk varied only minimally from 1.4 for FV Leiden to 1.6 for antithrombin deficiency compared with control women. Prophylactic anticoagulant treatment during pregnancy in 83 women with thrombophilia differed greatly in type, dose and duration, precluding solid conclusions on the effect of thromboprophylaxis on fetal loss. No clear benefit of anticoagulant prophylaxis was apparent.

CONCLUSIONS

Women with thrombophilia appear to have an increased risk of fetal loss, although the likelihood of a positive outcome is high in both women with thrombophilia and in controls.

Thrombophilia and pregnancy

Pregnancy is hypercoagulable state. The field of thrombophilia; the tendency to thrombosis, has been developed rapidly and has been linked to many aspects of pregnancy. It is recently that severe pregnancy complications such as severe preeclampsia intrauterine growth retardation abruptio placentae and stillbirth has been shown to be associated with thrombophilia. Recurrent miscarriage and has also been associated with thrombophilia. Finally, thromboembolism in pregnancy as in the non-pregnant state is linked to thrombophilia. In this review all aspects of thrombophilia in pregnancy are discussed, and also all prophylactic and therapeutic implications.

Inherited thrombophilia and poor pregnancy outcome

Gestational vascular complications are a major cause of maternal and fetal morbidity.A growing body of evidence suggests a significant role for inherited thrombophilia in the development of gestational vascular complications. While the majority of women with thrombophilia will have an uneventful gestation, case-control studies demonstrated that thrombophilia is more prevalent in cohorts of women with pregnancy loss and early-onset pre-eclampsia. Placental abruption and severe intrauterine growth restriction (IUGR) may also be associated with thrombophilia. Placental pathological findings in women with thrombophilia are hallmarked by thrombosis and fibrin deposition potentially to a greater degree than in normal pregnancy. Preliminary non-randomized studies suggest a benefit for prophylaxis with unfractionated and low-molecular-weight heparin (LMWH), and prospective randomized trials are in progress to define whether LMWH is effective in preventing pregnancy loss and other gestational vascular complications in women with thrombophilia and previous fetal wastage.

Inherited thrombophilia and pregnancy loss

A growing body of evidence obtained during the past 6 years suggests a significant role for inherited thrombophilia in the development of gestational vascular complications. Case-control and cross-sectional studies have demonstrated that thrombophilia is more prevalent in cohorts of women with pregnancy loss. Placental pathological findings in women with thrombophilia are hallmarked by thrombosis and fibrin deposition. Preliminary case-control studies suggest that low-molecular-weight heparins (LMWH) are effective in preventing pregnancy loss in women with thrombophilia and previous fetal wastage.

Thrombophilic disorders and fetal loss: a meta-analysis

BACKGROUND

Our aim was to assess the strength of the controversial association between thrombophilia and fetal loss, and to examine whether it varies according to the timing or definition of fetal loss.

METHODS

We searched Medline and Current Contents for articles published between 1975 and 2002 and their references with terms denoting recurrent fetal and non-recurrent fetal loss combined with various thrombophilic disorders. We included in our meta-analysis case-control, cohort, and cross-sectional studies published in English, the methodological quality of which was rated as moderate or strong. Pooled odds ratios (OR) with 95% CI were generated by random effects models with Cochrane Review Manager software.

FINDINGS

We included 31 studies. Factor V Leiden was associated with early (OR 2.01, 95% CI 1.13-3.58) and late (7.83, 2.83-21.67) recurrent fetal loss, and late non-recurrent fetal loss (3.26, 1.82-5.83). Exclusion of women with other pathologies that could explain fetal loss strengthened the association between Factor V Leiden and recurrent fetal loss. Activated protein C resistance was associated with early recurrent fetal loss (3.48, 1.58-7.69), and prothrombin G20210A mutation with early recurrent (2.56, 1.04-.29) and late non-recurrent (2.30, 1.09-4.87) fetal loss. Protein S deficiency was associated with recurrent fetal loss (14.72, 0.99-218.01) and late non-recurrent fetal loss (7.39, 1.28-42.63). Methylenetetrahydrofolate mutation, protein C, and antithrombin deficiencies were not significantly associated with fetal loss.

INTERPRETATION

The magnitude of the association between thrombophilia and fetal loss varies, according to type of fetal loss and type of thrombophilia.

Thromboprophylaxis improves the live birth rate in women with consecutive recurrent miscarriages and hereditary thrombophilia

The effect of thromboprophylaxis with low molecular weight heparin (LMWH), on the subsequent live birth rate, in thrombophilic women with recurrent miscarriage has not been sufficiently assessed. The present study is a cohort study undertaken to assess the effect of enoxaparin on the subsequent live birth rate in women with hereditary thrombophila. Eighty-five patients with three or more consecutive pregnancy losses and a hereditary thrombophilia subsequently conceived. Thirty-seven were treated with daily subcutaneous injections of enoxaparin 40 mg and 48 were not treated. The outcome of the subsequent pregnancy was assessed in both groups of patients in terms of live births or repeat miscarriage. Forty-seven of the 85 patients were subsequently delivered, 38 have miscarried. Twenty-six of the 37 pregnancies in treated patients (70.2%) resulted in live births, compared with 21 of 48 (43.8%) in untreated patients (P < 0.02, OR 3.03, 95% CI 1.12-8.36). The beneficial effect was seen mainly in primary aborters, i.e. women with no previous live births (P < 0.008, OR 9.75, 95% CI 1.59-52.48). This benefit was also found in patients with a poor prognosis for a live birth (five or more miscarriages), where the live birth rate was increased from 18.2% to 61.6%. However, the benefit was not statistically significant, probably due to the small number of patients. If the beneficial effects of enoxaparin are confirmed by additional studies, thromboprophylaxis can be recommended for patients with hereditary thrombophilia and recurrent pregnancy loss.

Activated protein C resistance and pregnancy loss

Activated protein C resistance is a thrombophilia with an established role in producing thrombosis which more recently has been implicated in the pathogenesis of pregnancy loss. This review will analyse recent literature to evaluate this association and address the gestation and type of pregnancy loss.

Thrombophilia and pregnancy loss

A large body of evidence obtained during the past 6 years suggests a significant role for inherited thrombophilia in the development of gestational vascular complications. While the majority of women with thrombophilia will have an uneventful gestation, case-control studies have demonstrated that thrombophilia is more prevalent in cohorts of women with pregnancy loss early onset preeclampsia, placental abruption, and severe intrauterine growth retardation (IUGR). Placental pathological findings in women with thrombophilia are hallmarked by thrombosis and fibrin deposition potentially to a greater degree than in normal pregnancy. Preliminary case-control studies suggest a benefit for prophylaxis with low molecular weight heparins (LMWH), and prospective randomized trials are in progress to define whether LMWH are effective in preventing pregnancy loss in women with thrombophilia and previous fetal wastage.

Clinical utility of factor V leiden (R506Q) testing for the diagnosis and management of thromboembolic disorders

OBJECTIVE

To review the current state of the art regarding the role of the clinical laboratory in diagnostic testing for the factor V Leiden (FVL) thrombophilic mutation (and other protein C resistance disorders), and to generate, through literature reviews and opinions of recognized thought-leaders, expert consensus recommendations on methodology and diagnostic, prognostic, and management issues pertaining to clinical FVL testing.

DATA SOURCES, EXTRACTION, AND SYNTHESIS

An initial thorough review of the medical literature and of current best clinical practices by a panel of 4 experts followed by a consensus conference review, editing, and ultimate approval by the majority of a panel of 28 additional coagulation laboratory experts.

CONCLUSIONS

Consensus recommendations were generated for topics of direct clinical relevance, including (1) defining those patients (and family members) who should (and should not) be tested for FVL; (2) defining the preferred FVL laboratory testing methods; and (3) defining the therapeutic, prophylactic, and management ramifications of FVL testing in affected individuals and their family members. As FVL is currently the most common recognized familial thrombophilia, it is hoped that these recommendations will assist laboratorians and clinicians caring for patients (and families) with this common mutation.

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.

Prevalence of genetic markers for thrombophilia in recurrent pregnancy loss

BACKGROUND

The genetic predispositions to venous thrombosis such as factor V Leiden (FVL) mutation (Arg 506 Gln), prothrombin (FII) gene mutation (G20210A), and mutation of the methylenetetrahydrofolate reductase (MTHFR) gene (C677T) have been reported to be associated with recurrent pregnancy loss. This paper examines the prevalence of markers for genetic thrombophilias in women with recurrent miscarriage.

METHODS

The prevalence of FVL, FII G20210A and MTHFR C677T was compared in 108 women with three or more pregnancy losses either exclusively in the first trimester, or mixed first and second trimester losses, with the prevalence found in 82 fertile parous control women without miscarriages. Markers for the thrombophilias were assessed by PCR analysis.

RESULTS

Twenty-three of the 108 patients (21.3%), had thrombophilia markers, which was similar to the proportion of patients in the control group (20.7%) with these markers. The prevalences of FVL and FII G20210A were lower in the study group than in the control group (3.7 versus 6.1% for FVL and 4.6 versus 6.1% for FII respectively); however, the difference was not statistically significant. In contrast, the prevalence of MTHFR C677T was higher in the study group than the control population (13 versus 8.5% respectively), but this difference was not statistically significant. There was no statistically significant prevalence of any particular thrombophilia in patients with previous first and second trimester pregnancy losses compared with patients with first trimester losses alone.

CONCLUSION

Thrombophilia was not found to be associated with recurrent pregnancy loss.

Inherited thrombophilia and stillbirth

Thrombophilias are inherited or acquired conditions that predispose individuals to thromboembolism. New inherited thrombophilias are recognized each year. Some, but not all, studies have found an association between inherited thrombophilias and adverse pregnancy outcomes, including fetal loss. The controversy regarding the clinical implications of thrombophilias in pregnancy is clouded by differences in study populations, the number of thrombophilias tested, interactions between thrombophilias, and the retrospective nature of most studies, just to name a few factors. The lack of adequately designed studies also extends to clinical management. Clear evidence to determine when to test, whom to test, which thrombophilias to test for, when to treat, and what to treat with is not available. Further studies to investigate these questions are urgently needed.

Thrombophilia is common in women with idiopathic pregnancy loss and is associated with late pregnancy wastage

OBJECTIVE

To describe the characteristics of thrombophilia in women with idiopathic pregnancy loss.

DESIGN

Prospective observational study.

SETTING

Tertiary referral center in a teaching academic hospital.

PATIENT(S)

One hundred forty-five patients with repeated pregnancy loss and 145 matched controls.

INTERVENTION(S)

Prospective assessment of thrombophilia in patients and controls.

MAIN OUTCOME MEASURE(S)

Prevalence of activated protein C (APC) resistance, protein C, protein S, and antithrombin III deficiencies, antiphospholipid antibodies, factor V Leiden, factor II G20210A, and MTHFR C677T mutations.

RESULT(S)

At least one thrombophilic defect was found in 66% of study group patients compared with 28% in control group patients. Combined thrombophilic defects were documented in 21% of women with pregnancy loss compared with 5.5% of control patients. Late pregnancy wastage occurred more frequently in women with thrombophilia compared with women without thrombophilia (160/429 [37%] vs. 39/162 [24%], respectively). APC resistance was documented in 39% of women with pregnancy loss compared with 3% of the control patients. APC resistance without factor V Leiden mutation was documented in 18% of women with pregnancy loss compared with none of the controls. While factor V Leiden mutation was more common in women with pregnancy loss (25% vs. 7.6%), factor II G20210A and homozygosity for MTHFR C677T contributed to pregnancy loss only in the presence of other thrombophilia.

CONCLUSION(S)

Thrombophilia was found in the majority (66%) of women with idiopathic pregnancy loss. APC resistance with or without factor V Leiden mutation is the most common thrombophilic defect, and combined thrombophilia is a frequent finding in women with pregnancy loss. Thrombophilia is associated with increased frequency of late pregnancy wastage.

Cerebrovascular disorders in children with the factor V Leiden mutation

Since 1995, at least 128 children with a cerebrovascular disorder, cerebral palsy, or both and the factor V Leiden mutation have been reported. The majority of these strokes were in the first year of life, many of them in the perinatal period. Two thirds had an additional exogenous risk factor for thrombosis, and 42% had another recognized endogenous prothrombotic risk factor in combination with the mutation. We review the association of the factor V Leiden mutation and a cerebrovascular disorder in children younger than 16 years of age and describe the clinical features of 8 children with cerebral palsy and the Leiden mutation. This mutation should be considered in the evaluation of children with a stroke or its sequelae, including infants with perinatal stroke.

Factor V Leiden: a clinical review

Factor V Leiden is the most prevalent genetic thrombophilia in people of European descent. Since its discovery, much clinical information has been gathered regarding the distribution and prevalence of the genetic mutation, the mechanism of thrombophilia, and its association with clinical thromboembolic events. Although its association with venous thromboembolism is clear, the role of Factor V Leiden in other disease states is not clear. A review of the literature regarding the mechanism of hypercoagulability, genetic versus functional diagnostic tests, screening issues, relationship to arterial thromboses, pregnancy and pregnancy complications, and treatment are discussed.

Which antiphospholipid antibody tests are most useful?

Despite an active international effort to improve diagnosis and treatment of the antiphospholipid syndrome (Hughes syndrome), there remain problems of lack of standardization and lack of prospective and multivariate epidemiologic analysis which restrict the diagnostic and predictive ability of commercially available tests. Nevertheless, current published series provide some data from which strategic approaches can be used to maximize the efficiency and usefulness of available tests. For further updates on new research and developments of interest to physicians and patients with this syndrome, the following web sites may prove helpful: www.slrapls.org, www.hematology.org, www.acforum.org, www.americanheart.org, www.rarediseases.org, www.aarda.org, and www.lupus.org.

Factor V Leiden and acquired activated protein C resistance among 1000 women with recurrent miscarriage

Activated protein C (APC) resistance, both in its congenital form, due to the factor V Leiden mutation, and in its acquired form, are important risk factors for systemic venous thrombosis. In view of the suspected thrombotic aetiology of some cases of recurrent miscarriage, the prevalence of APC resistance was determined among 1111 consecutive Caucasian women with a history of either recurrent early miscarriage (three or more consecutive pregnancy losses at <12 weeks gestation; n = 904) or a history of at least one late miscarriage (>12 weeks gestation; n = 207). A control group of 150 parous Caucasian women with no previous history of adverse pregnancy outcome was also studied. Acquired APC resistance was significantly more common among both women with recurrent early miscarriage (8.8%: 80/904; P = 0.02) and those with late miscarriage (8.7%: 18/207; P = 0.04) compared with controls (3.3%: 5/150). In contrast, the frequency of the factor V Leiden allele was similar among (i) women with recurrent early miscarriage (3.3%:60/1808; 58 heterozygotes and one homozygote), (ii) those with late miscarriage (3.9%:16/414; 14 heterozygotes and one homozygote) and (iii) the control group (4.0%:12/300; 12 heterozygotes). Acquired but not congenital APC resistance (due to the factor V Leiden mutation) is associated with both early and late miscarriage.

Tissue-restricted expression of thrombomodulin in the placenta rescues thrombomodulin-deficient mice from early lethality and reveals a secondary developmental block

The endothelial cell surface receptor thrombomodulin (TM) inhibits blood coagulation by forming a complex with thrombin, which then converts protein C into the natural anticoagulant, activated protein C. In mice, a loss of TM function causes embryonic lethality at day 8.5 p.c. (post coitum) before establishment of a functional cardiovascular system. At this developmental stage, TM is expressed in the developing vasculature of the embryo proper, as well as in non-endothelial cells of the early placenta, giant trophoblast and parietal endoderm. Here, we show that reconstitution of TM expression in extraembryonic tissue by aggregation of tetraploid wild-type embryos with TM-null embryonic stem cells rescues TM-null embryos from early lethality. TM-null tetraploid embryos develop normally during midgestation, but encounter a secondary developmental block between days 12.5 and 16.5 p.c. Embryos lacking TM develop lethal consumptive coagulopathy during this period, and no live embryos are retrieved at term. Morphogenesis of embryonic blood vessels and other organs appears normal before E15. These findings demonstrate a dual role of TM in development, and that a loss of TM function disrupts mouse embryogenesis at two different stages. These two functions of TM are exerted in two distinct tissues: expression of TM in non-endothelial extraembryonic tissues is required for proper function of the early placenta, while the absence of TM from embryonic blood vessel endothelium causes lethal consumptive coagulopathy.

Are women with polycystic ovary syndrome resistant to activated protein C?

OBJECTIVE

This study was performed to test the hypothesis that an increased prevalence of activated protein C (APC) resistance in women with polycystic ovary syndrome (PCOS) puts them at increased risk of miscarriage and thrombosis.

DESIGN

Case control study.

SETTING

A district general hospital in the United Kingdom.

PATIENT(S)

Forty-one women with PCOS and 25 controls.

INTERVENTION(S)

Clinical histories, ultrasound scans, and venepunctures.

MAIN OUTCOME MEASURE(S)

Diagnosis of PCOS or control, clinical histories, APC resistance according to an activated partial thromboplastin time-based assay.

RESULT(S)

There was no significant difference in the proportion of women with APC resistance in both groups (three women in the PCOS group [7%] vs. one woman in the control group [4%]). The prevalence of APC resistance in the entire study population was 6.5%. In the PCOS group, 29% (12/41) gave a positive family history of thrombosis compared with 8% (2/25) in the control group. None of the women with a positive family history of thrombosis had abnormal antithrombin 111, protein C, or protein S levels.

CONCLUSION(S)

This study suggests that women with PCOS may have the same prevalence of APC resistance as the background population and that APC resistance may not put them at a higher risk of thrombosis or miscarriage compared with the case of the general population.

Epidemiology and the medical causes of miscarriage

Human reproduction is extraordinarily wasteful. The reasons for this have taxed all of the contributors to this book. As we move into the 21st century it is sobering to reflect on the fact that we have failed to harness the power of the evolving revolution in molecular medical biology to answer the fundamental question: why is the fate of a fertilized egg so hazardous and so unsuccessful? The following account summarizes our limited knowledge of the epidemiology of miscarriage and then moves on to consider some of the medical causes of miscarriage. The contribution of genetic abnormalities to the problem of pregnancy wastage is discussed elsewhere in this volume.