Assessment-based management of placenta-mediated pregnancy complications: Pragmatism until a precision medicine approach evolves

The management of pregnant women with thrombophilia and a history of gestational vascular complications remains debatable. Treatment of the latter is often based on clinical outcome rather than disease mechanism. While the use of venous thromboembolism prophylaxis in pregnancy is recommended for those at increased risk, the ability of anticoagulant and/or antiplatelet agents to lower the risk of placenta-mediated complications in this clinical setting remains controversial. The available guidelines are inconsistent in some situations, which reflects the limited evidence base. This review critically discusses risk assessment models (RAMs) and management strategies of women with thrombophilia and pregnancy complications, using clinical vignettes. RAMs, taking into account obstetric and thrombotic history as well as thrombophilia status, could drive a precision medicine approach, based on disease mechanism, and guide individual therapeutic interventions in high-risk clinical settings.

United Kingdom recommendations for obstetric venous thromboembolism prophylaxis: Evidence and rationale

Venous thromboembolism (VTE) is a leading cause of maternal death in the United Kingdom. To address this problem guidance from the Royal College of Obstetricians and Gynaecologists (RCOG) has been developed that recommends the assessment of a woman's risk of thrombosis at specific time-points during pregnancy and postnatally at the time of delivery. The RCOG guidelines provide clinicians with a framework to inform decision-making on the use of thromboprophylaxis and are based on the premise that the higher risk a woman has for VTE, the more likely she is to benefit from prophylaxis - determining her level of risk is based on the number and characteristics of the risk factors that she has. This article will address the pathophysiology of VTE in pregnancy, evidence behind the risk factors for VTE and the use of thromboprophylactic agents. Further, it will reflect on the rationale behind the RCOG guidance.

Effect of Stanozolol on Factors VIII and IX and Serum Aminotransferases in Haemophilia

The treatment of haemophilia has been dramatically improved since the introduction of factor VIII and IX concentrates, however these concentrates have brought new problems such as hepatitis and A.I.D.S. An oral agent which could raise endogenous levels of factor VIII and IX would be of great benefit. Danazol, an anabolic steroid, has recently been shown to increase levels of factors VIII and IX in haemophilia. We therefore studied the effect of stanozolol, a closely related anabolic steroid, in 15 patients with haemophilia A or Christmas disease over a 2-4 week period. There was no consistent change in factor VIIIc or factor IX, and fibrinolysis was significantly enhanced. No effect was apparent on the incidence of spontaneous bleeds. However serum aminotransferases which were abnormal in 11 of the 15 patients at the start of the study fell significantly with stanozolol therapy. This raises the interesting possibility that anabolic steroids may be beneficial in patients with chronic liver diseases.

Risk Factors for Pregnancy Associated Venous Thromboembolism

In an attempt to reduce the incidence of pregnancy associated venous thromboembolism (PA-VTE), some researchers have advocated screening of all women for the factor VLeiden mutation during early pregnancy. We have conducted a large retrospective study (over 72,000 deliveries) to determine if this would be useful. Sixty-two objectively confirmed venous thrombotic events (51 DVT, 11 PE) were recorded at two maternity units in the UK. The incidence of DVT was 0.71 per 1000 deliveries (95% CI 0.5-0.9) with 0.50 occurring in the antenatal period (95% CI 0.34-0.66) and 0.21 in the puerperium (95% CI 0.11-0.31). The incidence of PE was 0.15 per 1000 deliveries (95% CI 0.06-0.24), 0.07 antenatal (95% CI 0.01-0.13) and 0.08 in the puerperium (95% CI 0.02-0.14). Of these 62,50 attended for follow-up and thrombophilia screening. 28% of all episodes of PA-VTE had no CIinical risk factor for thrombosis or an identifiable thrombophilic abnormality. Deficiency of antithrombin was identified in 12% of individuals (95% CI 3-21) and the factor VLeiden mutation in 8% (95% CI 0.5-15.5). Based on estimates of the prevalence of the factor VLeiden mutation in the population, we estimate that the thrombotic risk for a woman during pregnancy or the puerperium with the defect is approximately 1 in 400-500. This figure would not lend support to the idea of random screening for the mutation in early pregnancy.

Haemostatic Effects of Ketorolac with and without Concomitant Heparin in Normal Volunteers

Ketorolac is a potent cyclo-oxygenase inhibitor used for the treatment of postoperative pain. It is known to have anti-platelet properties. The aim of this study was to determine the effect of ketorolac on haemostasis both alone and in combination with tow dose heparin in LZ healthy male volunteers. Each volunteer received the following drug combinations in a double blind, placebo controlled, cross over manner: ketorolac placebo/heparin placebo, ketorolac active/heparin placebo, ketorolac active/heparin active and ketorolac placebo/heparin active. Ketorolac significantly prolonged bleeding time, inhibited platelet aggregation to arachidonic acid and collagen and platelet thromboxane production. Heparin had no effect on bleeding time or platelet function, but significantly prolonged the kaolin cephalin clotting time and increased anti-Xa levels. Ketorolac had no effect on the kaolin cephalin clotting time or anti-Xa levels and no interaction was found between ketorolac and heparin in any of the investigations. The prolongation of bleeding time seen with ketorolac is unlikely, to be of any major clinical significance as almost all subjects remained within the normal range; however, it should be used with caution in subjects with haemostatic problems.

Management of inherited thrombophilia in pregnancy

Adverse pregnancy outcomes, such as pregnancy loss and pre-eclampsia, are associated with thrombotic mechanisms and thrombophilia. Antithrombotic interventions, particularly low-molecular-weight heparin, have been investigated in women identified by previous pregnancy outcome; however, the results have been inconsistent. This may reflect heterogeneity of both the study groups and the disease processes resulting in inadequate stratification to guide antithrombotic interventions. Furthermore, the variation in gestation at initiation of low-molecular-weight heparin treatment might be important. Despite limited evidence of efficacy, low-molecular-weight heparin is often used in an attempt to prevent these complications, owing to the lack of other effective treatments and its perceived safety in pregnancy. Research is required to better understand the disease processes, identify possible biomarkers and thereby more homogeneous groups for targeted treatment.

LMWH in IVF - Biomarkers and benefits

There is biological plausibility that coagulation activation underlies a proportion of in vitro fertilisation IVF failures and recurrent early clinical pregnancy loss (RPL). However, low-molecular-weight heparin (LMWH) use, based upon previous clinical outcome alone, is not effective in preventing RPL. RPL is heterogeneous in mechanism. Identifying those with an underlying thrombotic mechanism would allow stratification for LMWH treatment. Annexin A5 is an anticoagulant protein expressed on the trophoblast surface. The annexin A5 M2 haplotype (ANXA5 M2) is associated with several placenta mediated pregnancy complications (PMPC) and poor IVF outcome. It is transmitted equally by males and females. A pragmatic observational study of IVF couples screened for M2 carriage and treated with LMWH achieved a 37.9% live birth rate, similar to an unscreened and untreated group with fewer adverse risk factors for conception and a better prognosis from assisted conception. This suggests that LMWH may counteract the adverse effects of M2 carriage. Using this biomarker to stratify IVF and PMPC patients for LMWH treatment merits further evaluation.

'To test or not to test', the arguments for and against thrombophilia testing in obstetrics

Clinicians increasingly investigate women for thrombophilias due to their associations with venous thromboembolism and placenta-mediated pregnancy complication. These associations, however, are modest and based largely on retrospective data from studies with heterogeneous classifications and populations, leading to discordance between evidence and guidelines. Current evidence suggests a contributory rather than causative role for thrombophilia in placenta-mediated pregnancy complication and venous thromboembolism. With little evidence of benefit from antithrombotic therapy in placenta-mediated pregnancy complication, thrombophilia screening remains controversial. Given the low absolute risk of placenta-mediated pregnancy complication and gestational venous thromboembolism with heritable thrombophilia, universal screening is inappropriate. Selective screening for antiphospholipid syndrome is supported by robust evidence of benefit. Conversely, selective screening for heritable thrombophilia has not been shown to effectively manage placenta-mediated pregnancy complication. Therefore, at present heritable thrombophilia screening is not warranted for placenta-mediated pregnancy complication. Until we have better evidence from better stratified patient groups, caution should remain if we wish to practice evidence-based medicine.

Leukocyte Density and Proinflammatory Mediator Expression in Regional Human Fetal Membranes and Decidua Before and During Labot at Term

OBJECTIVES

The region of fetal membranes overlying the cervix, known as the zone of altered morphology (ZAM), is considered to be the principle site of membrane inflammatory activity and extracellular matrix remodelling. We wished to quantify the relative contribution of each area of fetal membranes to the inflammatory process of parturition. Specifically, we aimed to quantify and compare (1) leukocyte densities in three regions of fetal membranes and decidua before and during spontaneous labor at term, and (2) mRNA expression of interleukin (IL)-1beta, IL-6, IL-8, cyclo-oxygenase type 1 (COX-1), and COX-2 in three regions of fetal membranes and decidua before and during spontaneous labor at term.

METHODS

Biopsies of fetal membranes and decidua were obtained from pregnant women delivered by cesarean section at term both before and during spontaneous labor (n = 8 both groups). Fetal membranes were sampled from three areas, the ZAM, midzone (MZ), and periplacental (PP) regions. Leukocytes were identified by immunohistochemistry and their density quantified. Inflammatory mediator expression was quantified using TaqMan technology (Applied Biosystems, Foster City, CA).

RESULTS

There was a significantly greater density of leukocytes in (1) the PP region of membranes compared with the ZAM, and (2) the decidua compared with amnion, amniotic connective tissue, and chorion. IL-1beta, IL-6, and IL-8 mRNA expression was significantly greater in all regions following spontaneous labor compared with nonlaboring tissues. There were no regional differences in cytokine expression within the fetal membranes. Choriodecidua expressed significantly more IL-1beta mRNA than amnion. Amnion expressed more COX-2 mRNA than choriodecidua.

CONCLUSIONS

All regions of fetal membranes and decidua contribute to the inflammatory process of human parturition; however, their relative contributions differ in magnitude. Although the ZAM may be specifically important for membrane rupture, it does not appear to play a key or exclusive role in the other inflammatory processes of parturition. When studying fetal membranes, it is relevant to identify and define the area sampled for consistency and comparison with other studies.

Precision Medicine in Assisted Conception: A Multicenter Observational Treatment Cohort Study of the Annexin A5 M2 Haplotype as a Biomarker for Antithrombotic Treatment to Improve Pregnancy Outcome

BACKGROUND

Pregnancy failure and placenta mediated pregnancy complications affect >25% of pregnancies. Although there is biological plausibility for a procoagulant mechanism underlying some of these events, antithrombotic intervention trials demonstrate limited benefit, possibly through lack of stratification in heterogeneous patient groups. The ANXA5 M2 haplotype is a possible procoagulant biomarker and was tested pragmatically to determine whether this screening and LMWH treatment normalized the outcome for ANXA5 M2 positive couples. This was a pragmatic study that aimed to measure the effectiveness of a testing (for the M2 haplotype) and treatment (LMWH) pathway in routine clinical practice where there is variation between patients. Such a study in couples with fertility problems can inform choices between treatments; it is then the management protocol which is the subject of the investigation, not the individual treatments.

METHODS

Couples (N=77) with one or both partners ANXA5 M2 positive demonstrated association of this haplotype with adverse IVF outcome. A pragmatic, multicenter, prospective cohort study of ANXA5 M2 haplotype screening, and LWMH treatment following embryo transfer (ET) in 103 IVF couples positive for ANXA5 M2 was performed. They were compared with a group of 1000 contemporaneous randomly selected unscreened and untreated couples undergoing assisted conception, from which 103 matched control couples were derived. The primary outcome measure was live birth incidence. Secondary outcomes were results following embryo transfer (ET) and live birth outcome by gender and M2 carriage, and allelic dose influence.

FINDINGS

The tested and treated cohort of ANXA5 M2 carriers achieved a similar live birth rate (37.9%) per ET cycle compared to both the more fertile comparison group (38.5%), and to the 103 matched controls (33.0%). Significantly more treated male carrier only couples had a live birth versus female M2 only (47.7% vs. 25.0% p=0.045).

INTERPRETATION

Pragmatic ANXA5 M5 screening and treatment with LMWH in couples undergoing IVF is associated with similar outcome to couples with more favorable prognostic factors. The difference in live birth outcome for treated male only carrier couples may be consistent with an additional maternal thrombophilic factor that may adversely affect pregnancy, although other mechanisms are possible. This study suggests that LMWH treatment should be started prior to clinical pregnancy.

Pulmonary thrombo-embolism in pregnancy: diagnosis and management

KEY POINTS

Venous thromboembolism (VTE) in pregnancy remains a leading cause of direct maternal mortality in the developed world and identifiable risk factors are increasing in incidence.VTE is approximately 10-times more common in the pregnant population (compared with non-pregnant women) with an incidence of 1 in 1000 and the highest risk in the postnatal period.If pulmonary imaging is required, ventilation perfusion scanning is usually the preferred initial test to detect pulmonary embolism within pregnancy. Treatment should be commenced on clinical suspicion and not be withheld until an objective diagnosis is obtained.The mainstay of treatment for pulmonary thromboembolism in pregnancy is anticoagulation with low molecular weight heparin for a minimum of 3 months in total duration and until at least 6 weeks postnatal. Low molecular weight heparin is safe, effective and has a low associated bleeding risk.

EDUCATIONAL AIMS

To inform readers about the current guidance for diagnosis and management of pulmonary thromboembolism in pregnancy.To highlight the risks of venous thromboembolism during pregnancy.To introduce the issues surrounding management of pulmonary thromboembolism around labour and delivery.

Thrombophilia and Pregnancy Complications

There is a paucity of strong evidence associated with adverse pregnancy outcomes and thrombophilia in pregnancy. These problems include both early (recurrent miscarriage) and late placental vascular-mediated problems (fetal loss, pre-eclampsia, placental abruption and intra-uterine growth restriction). Due to poor quality case-control and cohort study designs, there is often an increase in the relative risk of these complications associated with thrombophilia, particularly recurrent early pregnancy loss, late fetal loss and pre-eclampsia, but the absolute risk remains very small. It appears that low-molecular weight heparin has other benefits on the placental vascular system besides its anticoagulant properties. Its use is in the context of antiphospholipid syndrome and recurrent pregnancy loss and also in women with implantation failure to improve live birth rates. There is currently no role for low-molecular weight heparin to prevent late placental-mediated complications in patients with inherited thrombophilia and this may be due to small patient numbers in the studies involved in summarising the evidence. There is potential for low-molecular weight heparin to improve pregnancy outcomes in women with prior severe vascular complications of pregnancy such as early-onset intra-uterine growth restriction and pre-eclampsia but further high quality randomised controlled trials are required to answer this question.

Antepartum dalteparin versus no antepartum dalteparin for the prevention of pregnancy complications in pregnant women with thrombophilia (TIPPS): a multinational open-label randomised trial

BACKGROUND

Thrombophilias are common disorders that increase the risk of pregnancy-associated venous thromboembolism and pregnancy loss and can also increase the risk of placenta-mediated pregnancy complications (severe pre-eclampsia, small-for-gestational-age infants, and placental abruption). We postulated that antepartum dalteparin would reduce these complications in pregnant women with thrombophilia.

METHODS

In this open-label randomised trial undertaken in 36 tertiary care centres in five countries, we enrolled consenting pregnant women with thrombophilia at increased risk of venous thromboembolism or with previous placenta-mediated pregnancy complications. Eligible participants were randomly allocated in a 1:1 ratio to either antepartum prophylactic dose dalteparin (5000 international units once daily up to 20 weeks' gestation, and twice daily thereafter until at least 37 weeks' gestation) or to no antepartum dalteparin (control group). Randomisation was done by a web-based randomisation system, and was stratified by country and gestational age at randomisation day with a permuted block design (block sizes 4 and 8). At randomisation, site pharmacists (or delegates) received a randomisation number and treatment allocation (by fax and/or e-mail) from the central web randomisation system and then dispensed study drug to the local coordinator. Patients and study personnel were not masked to treatment assignment, but the outcome adjudicators were masked. The primary composite outcome was independently adjudicated severe or early-onset pre-eclampsia, small-for-gestational-age infant (birthweight <10th percentile), pregnancy loss, or venous thromboembolism. We did intention-to-treat and on-treatment analyses. This trial is registered with ClinicalTrials.gov, number NCT00967382, and with Current Controlled Trials, number ISRCTN87441504.

FINDINGS

Between Feb 28, 2000, and Sept 14, 2012, 292 women consented to participate and were randomly assigned to the two groups. Three women were excluded after randomisation because of ineligibility (two in the antepartum dalteparin group and one in the control group), leaving 146 women assigned to antepartum dalteparin and 143 assigned to no antepartum dalteparin. Some patients crossed over to the other group during treatment, and therefore for on-treatment and safety analysis there were 143 patients in the dalteparin group and 141 in the no dalteparin group. Dalteparin did not reduce the incidence of the primary composite outcome in both intention-to-treat analysis (dalteparin 25/146 [17·1%; 95% CI 11·4-24·2%] vs no dalteparin 27/143 [18·9%; 95% CI 12·8-26·3%]; risk difference -1·8% [95% CI -10·6% to 7·1%)) and on-treatment analysis (dalteparin 28/143 [19·6%] vs no dalteparin 24/141 [17·0%]; risk difference +2·6% [95% CI -6·4 to 11·6%]). In safety analysis, the occurrence of major bleeding did not differ between the two groups. However, minor bleeding was more common in the dalteparin group (28/143 [19·6%]) than in the no dalteparin group (13/141 [9·2%]; risk difference 10·4%, 95% CI 2·3-18·4; p=0·01).

INTERPRETATION

Antepartum prophylactic dalteparin does not reduce the occurrence of venous thromboembolism, pregnancy loss, or placenta-mediated pregnancy complications in pregnant women with thrombophilia at high risk of these complications and is associated with an increased risk of minor bleeding.

FUNDING

Canadian Institutes of Health Research, Heart and Stroke Foundation of Canada, and Pharmacia and UpJohn.

Coagulation and placenta-mediated complications

Pregnancy is a physiological hypercoagulable state, preparing the mother for the hemostatic challenge of delivery. However, this is associated with an increased risk of venous thrombosis and placenta-mediated complications, which present major challenges for mother and fetus. Although these conditions are heterogeneous in their pathophysiology, hereditary and acquired thrombophilia has been associated with recurrent pregnancy loss and gestational vascular complications, such as early-onset pre-eclampsia and placental abruption. Prevention of such placenta-mediated complications, which collectively complicate up to 15% of pregnancies, is a major issue for women's health. Prospective interventional studies stratified by current knowledge of pathophysiological mechanisms related to placental and systemic hemostatic alterations will impact on the management of pregnancies at risk of these complications.

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

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

Hypertensive disorders of pregnancy: preventative-, immediate- and long-term management

The hypertensive disorders of pregnancy are common and continue to be significant contributors to maternal and perinatal mortality and morbidity, both globally and in the UK. This review aims to describe the recent developments in the understanding of the pathophysiology of the disease processes, potential strategies for identification of women at high risk, and current and future therapeutic strategies for the treatment and prevention of hypertension in pregnancy. Women who experience adverse pregnancy outcomes are also at increased risk of premature cardiovascular disease, and potential therapeutic strategies to minimize their risk profile are discussed.

Preeclampsia is associated with compromised maternal synthesis of long-chain polyunsaturated fatty acids, leading to offspring deficiency

Obesity and excessive lipolysis are implicated in preeclampsia (PE). Intrauterine growth restriction is associated with low maternal body mass index and decreased lipolysis. Our aim was to assess how maternal and offspring fatty acid metabolism is altered in mothers in the third trimester of pregnancy with PE (n=62) or intrauterine growth restriction (n=23) compared with healthy pregnancies (n=164). Markers of lipid metabolism and erythrocyte fatty acid concentrations were measured. Maternal adipose tissue fatty acid composition and mRNA expression of adipose tissue fatty acid-metabolizing enzymes and placental fatty acid transporters were compared. Mothers with PE had higher plasma triglyceride (21%, P<0.001) and nonesterified fatty acid (50%, P<0.001) concentrations than controls. Concentrations of major n-6 and n-3 long-chain polyunsaturated fatty acids in erythrocytes were 23% to 60% lower (all P<0.005) in PE and intrauterine growth restriction mothers and offspring compared with controls. Subcutaneous adipose tissue Δ-5 and Δ-6 desaturase and very long-chain fatty acid elongase mRNA expression was lower in PE than controls (respectively, mean [SD] control 3.38 [2.96] versus PE 1.83 [1.91], P=0.030; 3.33 [2.25] versus 1.03 [0.96], P<0.001; 0.40 [0.81] versus 0.00 [0.00], P=0.038 expression relative to control gene [square root]). Low maternal and fetal long-chain polyunsaturated fatty acid concentrations in PE may be the result of decreased maternal synthesis.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

The influence of maternal Lewis, Secretor and ABO(H) blood groups on fetal growth restriction

BACKGROUND

Fetal growth restriction (FGR) is associated with thrombosis of the placenta and an increased risk of subsequent vascular disease in the mother and fetus. The products of interactions between ABO(H), Lewis and Secretor genes are also associated with thrombosis and vascular disease risk.

OBJECTIVES/METHODS

A prospective case-control study of mothers with a severe FGR pregnancy (cases, n = 128; controls, n = 288) was performed to determine whether FGR is associated with particular maternal blood groups.

RESULTS

No association with ABO(H) status was observed, but FGR was more common in maternal secretors (odds ratio [OR] 1.70, 95% confidence interval [CI] 1.08-2.69) and consequently in those mothers expressing Le(b) on their red cells (OR 1.80, 95% CI 1.15-2.83), with a reduced risk in non-secretors and those expressing Le(a). Given the association between blood groups and both activated protein C resistance (APCR) and von Willebrand factor (VWF) levels, post hoc pilot studies on first-trimester APCR and VWF antigen levels and blood group genotypes were performed. No relationship with Lewis or Secretor was observed. Despite this, lower first-trimester VWF levels were observed in pregnancies subsequently complicated by FGR.

CONCLUSIONS

 This is the first study reporting a relationship between maternal Secretor/Lewis status and FGR. A link between blood groups and FGR is plausible, as both are associated with cardiovascular disease. We observed no relationship between Lewis/Secretor status and VWF or APCR, but this should be confirmed in a larger study. Thus, the mechanism whereby Secretor and/or Lewis influences FGR is unknown.

Tinzaparin use in pregnancy: an international, retrospective study of the safety and efficacy profile

OBJECTIVES

This study audited pregnancies where the mother received tinzaparin (at any stage before delivery), with a primary objective of determining the maternal safety of this low molecular weight heparin when administered as treatment and/or prophylaxis; the secondary objective was to audit fetal and neonatal safety in this cohort. Efficacy outcomes were also recorded.

STUDY DESIGN

The audit period was 1996-2009; consecutive, retrospective pregnancy records at participating hospitals were reviewed. For those records documenting tinzaparin use and pregnancy outcome, information was extracted into a standardised case report form; these were reviewed for adverse events, which were submitted for adjudication by independent experts in obstetric medicine and haematology. Endpoints were presented using descriptive statistics for all pregnancies, and by reason for tinzaparin use (treatment of venous thromboembolism [VTE] and prophylaxis).

RESULTS

There were 28 participating hospital centres in eight countries (Belgium, Canada, Denmark, Ireland, Netherlands, Sweden, Spain and the UK). Data were collected from 1267 pregnancies (1120 women; 1303 fetuses); in 254 pregnancies the women received tinzaparin as treatment (median dose 13,000 international units [IU]/day, range 3500-23,100IU/day; median duration 72 days; 94.1% once-daily), and in 1013 pregnancies the women received tinzaparin for prophylaxis (median dose 4500IU/day, range 2500-21,811IU/day, median duration 183 days, 94.6% once-daily). There were 871 (70.2%) vaginal deliveries (78 assisted) and 369 (29.8%) caesarean sections (27 delivery data missing). Overall, 495 (39.3%) women had neuraxial anaesthesia; however, there were no reported associated haematomas. There were no maternal deaths. Of pregnancies with available data (1060), 86.9% had blood loss ≤500mL, 11.0% of >500 to ≤1000mL, 0.9% >1000 to ≤1500mL and 1.1% >1500mL. There were 1245 (95.5%) live births, 15 (1.2%) stillbirths, 40 (3.1%) miscarriages and 3 (0.2%) terminations. Six (0.5%) neonatal deaths occurred (five at <27 weeks, one Ebstein's anomaly). No neonatal haemorrhages occurred. Adjudicated safety outcomes included 125 (9.9%) 'any bleeding' cases considered related to tinzaparin; 16 (1.3%) of these required medical intervention. In the treatment group, five (2%) recurrent VTEs were reported and 10 (1%) occurred in the prophylaxis group.

CONCLUSIONS

These data provide reassuring maternal and fetal outcome information in pregnancies exposed to tinzaparin.

Antithrombotic treatment for recurrent pregnancy loss?

BACKGROUND

Recurrent pregnancy loss (RPL) is a major issue for women's health. Acquired and heritable thrombophilias are associated with RPL, this association could reflect a general prothrombotic phenotype rather than a specific thrombophilia. Antithrombotic intervention has therefore been assessed for RPL.

RESULTS

Two large randomised trials with untreated control groups showed no benefit from antithrombotic treatment with LMWH and low dose aspirin in women with RPL. These trials had insufficient power to exclude an effect in women with underlying thrombophilia, ≥ 3 losses, or late losses.

CONCLUSIONS

Antithrombotic intervention should not be recommended for unexplained RPL in general. There may be specific groups such as those with an heritable thrombophilia, or with three or more losses, or second trimester losses that might benefit and where further trials are required. Further there is a need to consider the benefits of LMWH on implantation such as in women undergoing assisted conception therapy.

Incident venous thromboembolic events in the Prospective Study of Pravastatin in the Elderly at Risk (PROSPER)

Background

Venous thromboembolic events (VTE), including deep venous thrombosis and pulmonary embolism, are common in older age. It has been suggested that statins might reduce the risk of VTE however positive results from studies of middle aged subjects may not be generalisable to elderly people. We aimed to determine the effect of pravastatin on incident VTE in older people; we also studied the impact of clinical and plasma risk variables.

Methods

This study was an analysis of incident VTE using data from the Prospective Study of Pravastatin in the Elderly at Risk (PROSPER), a randomized, double-blind, placebo-controlled trial of pravastatin in men and women aged 70-82. Mean follow-up was 3.2 years. Risk for VTE was examined in non-warfarin treated pravastatin (n = 2834) and placebo (n = 2865) patients using a Cox's proportional hazard model, and the impact of other risk factors assessed in a multivariate forward stepwise regression analysis. Baseline clinical characteristics, blood biochemistry and hematology variables, plasma levels of lipids and lipoproteins, and plasma markers of inflammation and adiposity were compared. Plasma markers of thrombosis and hemostasis were assessed in a nested case (n = 48) control (n = 93) study where the cohort was those participants, not on warfarin, for whom data were available.

Results

There were 28 definite cases (1.0%) of incident VTE in the pravastatin group recipients and 20 cases (0.70%) in placebo recipients. Pravastatin did not reduce VTE in PROSPER compared to placebo [unadjusted hazard ratio (95% confidence interval) 1.42 (0.80, 2.52) p = 0.23]. Higher body mass index (BMI) [1.09 (1.02, 1.15) p = 0.0075], country [Scotland vs Netherlands 4.26 (1.00, 18.21) p = 0.050 and Ireland vs Netherlands 6.16 (1.46, 26.00) p = 0.013], lower systolic blood pressure [1.35 (1.03, 1.75) p = 0.027] and lower baseline Mini Mental State Examination (MMSE) score [1.19 (1.01, 1.41) p = 0.034] were associated with an increased risk of VTE, however only BMI, country and systolic blood pressure remained significant on multivariate analysis. In a nested case control study of definite VTE, plasma Factor VIII levels were associated with VTE [1.52 (1.01, 2.28), p = 0.044]. However no other measure of thrombosis and haemostasis was associated with increased risk of VTE.

Conclusions

Pravastatin does not prevent VTE in elderly people at risk of vascular disease. Blood markers of haemostasis and inflammation are not strongly predictive of VTE in older age however BMI, country and lower systolic blood pressure are independently associated with VTE risk.

Trial Registration

Not applicable when study undertaken.

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

BACKGROUND

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

METHODS AND FINDINGS

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

CONCLUSIONS

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

Chemokine scavenger D6 is expressed by trophoblasts and aids the survival of mouse embryos transferred into allogeneic recipients

Proinflammatory CC chemokines are thought to drive recruitment of maternal leukocytes into gestational tissues and regulate extravillous trophoblast migration. The atypical chemokine receptor D6 binds many of these chemokines and is highly expressed by the human placenta. D6 is thought to act as a chemokine scavenger because, when ectopically expressed in cell lines in vitro, it efficiently internalizes proinflammatory CC chemokines and targets them for destruction in the absence of detectable chemokine-induced signaling. Moreover, D6 suppresses inflammation in many mouse tissues, and notably, D6-deficient fetuses in D6-deficient female mice show increased susceptibility to inflammation-driven resorption. In this paper, we report strong anti-D6 immunoreactivity, with specific intracellular distribution patterns, in trophoblast-derived cells in human placenta, decidua, and gestational membranes throughout pregnancy and in trophoblast disease states of hydatidiform mole and choriocarcinoma. We show, for the first time, that endogenous D6 in a human choriocarcinoma-derived cell line can mediate progressive chemokine scavenging and that the D6 ligand CCL2 can specifically associate with human syncytiotrophoblasts in term placenta in situ. Moreover, despite strong chemokine production by gestational tissues, levels of D6-binding chemokines in maternal plasma decrease during pregnancy, even in women with pre-eclampsia, a disease associated with increased maternal inflammation. In mice, D6 is not required for syngeneic or semiallogeneic fetal survival in unchallenged mice, but interestingly, it does suppress fetal resorption after embryo transfer into fully allogeneic recipients. These data support the view that trophoblast D6 scavenges maternal chemokines at the fetomaternal interface and that, in some circumstances, this can help to ensure fetal survival.

Obesity in pregnancy: risks and management

Maternal obesity is now considered one of the most commonly occurring risk factors seen in obstetric practice. Compared with women with a healthy pre-pregnancy weight, women with obesity are at increased risk of miscarriage, gestational diabetes, preeclampsia, venous thromboembolism, induced labour, caesarean section, anaesthetic complications and wound infections, and they are less likely to initiate or maintain breastfeeding. Babies of obese mothers are at increased risk of stillbirth, congenital anomalies, prematurity, macrosomia and neonatal death. Intrauterine exposure to obesity is also associated with an increased risk of developing obesity and metabolic disorders in childhood. This article reviews the prevalence of obesity in pregnancy and the associated maternal and fetal complications. Recommendations and suggestions for pre-conception, antenatal and postnatal care of women with obesity are presented, and current research in the UK and future research priorities are considered.

Pregnancy after bariatric surgery: no problem?

Bariatric surgery is highly effective for weight loss in morbid obesity. With the high prevalence of severe obesity in the developed world, and the acknowledgement of the effectiveness of these procedures by National Institute for Clinical Excellence (in the UK) and the Food and Drug Administration (in the USA), women with severe obesity will increasingly seek such treatment. As the majority of these patients are women of reproductive age, obstetricians will encounter these patients frequently during pregnancy. It is therefore important for obstetricians to gain an insight into the types of surgery performed, the potential complications, including nutritional deficiency, and appropriate management of pregnancy following weight-loss surgery. In general, bariatric surgery is associated with a reduction in obesity related complication, with no apparent increased risk of adverse perinatal outcomes.

Vascular dysfunction and alteration of novel and classic cardiovascular risk factors in mothers of growth restricted offspring

OBJECTIVE

Offspring and maternal birthweight are inversely associated with maternal cardiovascular disease. However, whether established or putative novel cardiovascular risk factors including vascular and metabolic function are disrupted in women who delivered small for gestational age (SGA) offspring is unknown.

METHODS

Case control study with analysis of inflammatory, lipid, metabolic and haemostatic markers and microvascular function as assessed by laser Doppler iontophoresis 4 years after the index pregnancy in 28 mothers who delivered SGA offspring at term and 29 matched controls.

RESULTS

Delivery of a SGA infant was associated with altered lipids [triglyceride median (IQR) mmol/l; control 0.64 (0.49-0.84); SGA 0.95 (0.67-0.95), p=0.012] [cholesterol:HDL ratio: control 2.64 (2.10-3.10); SGA 3.06 (2.65-3.89), p=0.013], systolic blood pressure [control mmHg: 110 (108-118); SGA 120 (110-130), p=0.031], subclinical inflammation [CRP mg/l: control 0.7 (0.3-2.1); SGA 2.2 (1.2-4.0), p=0.002] [IL-6 pg/ml: control 1.2 (0.8-1.4); SGA 1.5 (1.1-2.2), p=0.009] and endothelial activation [ICAM-1 ng/ml: control 237.7 (210.0-279.4); SGA 283.1 (240.5-366.3), p=0.013], with differences robust to confounder adjustment. Endothelium dependent (p=0.003) and independent microvascular function (p<0.001) were also impaired in mothers of SGA offspring.

CONCLUSIONS

Mothers of term SGA offspring exhibit perturbation of metabolic and vascular function, which may underlie a lifelong trajectory of impaired health incorporating adverse perinatal and cardiovascular events.

Venous thromboembolism, thrombophilia, antithrombotic therapy, and pregnancy: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition)

This article discusses the management of venous thromboembolism (VTE) and thrombophilia, as well as the use of antithrombotic agents, during pregnancy and is part of the American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). Grade 1 recommendations are strong and indicate that benefits do, or do not, outweigh risks, burden, and costs. Grade 2 recommendations are weaker and imply that the magnitude of the benefits and risks, burden, and costs are less certain. Support for recommendations may come from high-quality, moderate-quality or low-quality studies; labeled, respectively, A, B, and C. Among the key recommendations in this chapter are the following: for pregnant women, in general, we recommend that vitamin K antagonists should be substituted with unfractionated heparin (UFH) or low-molecular-weight heparin (LMWH) [Grade 1A], except perhaps in women with mechanical heart valves. For pregnant patients, we suggest LMWH over UFH for the prevention and treatment of VTE (Grade 2C). For pregnant women with acute VTE, we recommend that subcutaneous LMWH or UFH should be continued throughout pregnancy (Grade 1B) and suggest that anticoagulants should be continued for at least 6 weeks postpartum (for a total minimum duration of therapy of 6 months) [Grade 2C]. For pregnant patients with a single prior episode of VTE associated with a transient risk factor that is no longer present and no thrombophilia, we recommend clinical surveillance antepartum and anticoagulant prophylaxis postpartum (Grade 1C). For other pregnant women with a history of a single prior episode of VTE who are not receiving long-term anticoagulant therapy, we recommend one of the following, rather than routine care or full-dose anticoagulation: antepartum prophylactic LMWH/UFH or intermediate-dose LMWH/UFH or clinical surveillance throughout pregnancy plus postpartum anticoagulants (Grade 1C). For such patients with a higher risk thrombophilia, in addition to postpartum prophylaxis, we suggest antepartum prophylactic or intermediate-dose LMWH or prophylactic or intermediate-dose UFH, rather than clinical surveillance (Grade 2C). We suggest that pregnant women with multiple episodes of VTE who are not receiving long-term anticoagulants receive antepartum prophylactic, intermediate-dose, or adjusted-dose LMWH or intermediate or adjusted-dose UFH, followed by postpartum anticoagulants (Grade 2C). For those pregnant women with prior VTE who are receiving long-term anticoagulants, we recommend LMWH or UFH throughout pregnancy (either adjusted-dose LMWH or UFH, 75% of adjusted-dose LMWH, or intermediate-dose LMWH) followed by resumption of long-term anticoagulants postpartum (Grade 1C). We suggest both antepartum and postpartum prophylaxis for pregnant women with no prior history of VTE but antithrombin deficiency (Grade 2C). For all other pregnant women with thrombophilia but no prior VTE, we suggest antepartum clinical surveillance or prophylactic LMWH or UFH, plus postpartum anticoagulants, rather than routine care (Grade 2C). For women with recurrent early pregnancy loss or unexplained late pregnancy loss, we recommend screening for antiphospholipid antibodies (APLAs) [Grade 1A]. For women with these pregnancy complications who test positive for APLAs and have no history of venous or arterial thrombosis, we recommend antepartum administration of prophylactic or intermediate-dose UFH or prophylactic LMWH combined with aspirin (Grade 1B). We recommend that the decision about anticoagulant management during pregnancy for pregnant women with mechanical heart valves include an assessment of additional risk factors for thromboembolism including valve type, position, and history of thromboembolism (Grade 1C). While patient values and preferences are important for all decisions regarding antithrombotic therapy in pregnancy, this is particularly so for women with mechanical heart valves. For these women, we recommend either adjusted-dose bid LMWH throughout pregnancy (Grade 1C), adjusted-dose UFH throughout pregnancy (Grade 1C), or one of these two regimens until the thirteenth week with warfarin substitution until close to delivery before restarting LMWH or UFH) [Grade 1C]. However, if a pregnant woman with a mechanical heart valve is judged to be at very high risk of thromboembolism and there are concerns about the efficacy and safety of LMWH or UFH as dosed above, we suggest vitamin K antagonists throughout pregnancy with replacement by UFH or LMWH close to delivery, after a thorough discussion of the potential risks and benefits of this approach (Grade 2C).

Fetal corticotrophin-releasing hormone mRNA, but not phosphatidylserine-exposing microparticles, in maternal plasma are associated with factor VII activity in pre-eclampsia

BACKGROUND

Pre-eclampsia is associated with increased placental debris circulating in maternal plasma.

OBJECTIVES

This study related placental debris to maternal markers of coagulation and endothelial activation in pre-eclampsia.

PATIENTS/METHODS

Circulating fetal corticotrophin-releasing hormone (CRH) mRNA and phosphatidylserine (PS)-exposing microparticles were assayed in third trimester plasma from women with pre-eclampsia (n = 32) and controls (n = 32) matched for age, body mass index, parity, and gestational age at sampling. Markers of maternal hemostasis and endothelial function were assessed.

RESULTS

Fetal CRH mRNA levels were higher in pre-eclampsia [mean 0.75 (SD 2.77) CRH/glyceraldehyde-3-phosphate dehydrogenase (GAPDH) mRNA ratio] than in control pregnancies [0.20 (0.74), P = 0.014]. PS-exposing microparticle levels were not different between the groups. Women with pre-eclampsia had higher levels of tissue factor pathway inhibitor (TFPI), prothrombin F(1+2) fragment (F(1+2)), factor XIIa, soluble vascular cell adhesion molecule 1, von Willebrand factor and plasminogen activator inhibitor 1 than controls. Fetal CRH mRNA correlated with TFPI in pre-eclampsia and control groups (r = 0.38, P = 0.031, and r = 0.37, P = 0.039, respectively). Fetal CRH mRNA correlated with FVII activity (r = 0.43, P = 0.017) and PS-exposing microparticles correlated inversely with F(1+2) (r = -0.64, P < 0.001) in pre-eclampsia.

CONCLUSIONS

Placental debris, assessed by fetal CRH mRNA levels in maternal blood, is related to coagulation potential, i.e. FVII activity, but not to markers of coagulation or endothelial activation in pre-eclampsia.