Reference intervals for plasma levels of fibronectin, von Willebrand factor, free protein S and antithrombin during third-trimester pregnancy

Pathophysiological, immunogenetic, anatomopathological profile of thrombophilia in pregnancy

Thrombophilic states have been associated with early and/or late pregnancy loss and possibly other severe obstetrical complications. Pregnancy-induced hypercoagulability, increased stasis, and the consequences of inherited and acquired thrombophilia are just a few of the factors that contribute to the development of thrombosis in pregnancy. In this review, we illustrate the impact that these factors have on the development of thrombophilia during pregnancy. We also explore how thrombophilia impact pregnancy outcomes. Next, we discuss how human leukocyte antigen G plays a part in thrombophilia during pregnancy by regulating cytokine release to prevent trophoblastic cell invasion and maintain local immunotolerance constant. Human leukocyte antigen class E is briefly explored with thrombophilia in pregnancy. Regarding the anatomopathologic aspect, we describe the different histopathological lesions of the placenta found in women with thrombophilia.

Plasma Antithrombin Activity during Long-Term Magnesium Sulfate Administration for Preeclampsia without Severe Hypertension

In preeclampsia, plasma antithrombin activity is decreased, which leads to exacerbation of the disorder. We previously showed that long-term magnesium sulfate (MgSO₄) administration prolonged the pregnancy period and may be able to improve pregnancy outcomes for patients with severe preeclampsia. The present study aimed to investigate the changes in plasma antithrombin activity during long-term MgSO₄ administration for patients without severe hypertension. This multicenter retrospective study included patients with preeclampsia and superimposed preeclampsia without severe hypertension at diagnosis. The participants were divided into two groups: MgSO₄ nontreatment group (three institutions) and MgSO₄ treatment group (one institution). Antithrombin activity from time of diagnosis to delivery were compared between the two groups. In the MgSO₄ nontreatment group (n = 16), antithrombin activity prior to delivery was significantly lower than at time of diagnosis (p = 0.015). In three cases, antithrombin activity was less than 60%. On the other hand, in the MgSO₄ treatment group (n = 34), antithrombin activity did not change until just before delivery (p = 0.74). There were no cases in which antithrombin activity was decreased below 60%. Long-term MgSO₄ administration for preeclampsia without severe hypertension may prevent a decrease in antithrombin activity and improve the disease state of preeclampsia.

Reference intervals for coagulation parameters in non-pregnant and pregnant women

Established reference intervals (RIs) of coagulation parameters generally based on the general population are not applicable to specific women. In order to accurately evaluate the coagulation status of non-pregnant women and pregnant women, specific RIs should be established. Our study recruited 465 non-pregnant women and 1972 pregnant women aged 20–45 years. Eight tests including antithrombin (AT), protein C (PC), free protein S (fPS), lupus anticoagulant (LA), D-dimer, fibrin/fibrinogen degradation products (FDP), coagulation factor VII (FVII), and factor VIII (FVIII) were performed on ACL TOP automated coagulation instrument. The RIs for these tests were established in non-pregnant and pregnant women at different gestational weeks. Compared to the non-pregnant group, the medians of AT and fPS were lower, while the medians of PC, LA normalized ratio, D-dimer, FDP, FVII, and FVIII were higher. During pregnancy, AT and fPS activity showed a decreasing trend, with the increase of gestational age. PC activity, LA normalized ratio, D-dimer concentrations, FDP concentrations, FVII, and FVIII activity presented an increasing trend, with the increase of gestational age. The non-pregnant women-specific RIs and the gestational age-specific RIs of AT, PC, fPS, LA normalized ratio, D-dimer, FDP, FVII, and FVIII needed to be established for accurate clinical diagnoses.

Physiological and metabolic adaptations in pregnancy: importance of trimester-specific reference intervals to investigate maternal health and complications

Diagnosis, prognostication, and monitoring of maternal health throughout pregnancy relies on laboratory testing, including but not limited to key markers of thyroid, hepatic, cardiac, hematology, and renal function. Dynamic physiological processes during gestation significantly influence the maternal biochemistry that supports both the mother and fetus. Resultant changes in blood biochemistry alter the expected values of common laboratory tests. However, the importance of pregnancy-specific reference intervals for laboratory test result interpretation and appropriate monitoring of maternal health and complications is underappreciated. Most clinical laboratories continue to use non-pregnant adult reference intervals for laboratory test interpretation in pregnancy. The current review summarizes and critically evaluates the available literature regarding physiological and metabolic adaptations in pregnancy and their influence on common biomarkers of health and disease. The main laboratory parameters discussed include thyroid, hepatic, metabolic, renal, hematology, inflammatory, and cardiac markers. Considering the available data, further studies are urgently needed to establish trimester-specific reference intervals in healthy pregnant women on updated analytical platforms. Without such data, the standard of clinical laboratory service in pregnancy remains compromised and affects the quality of maternal-fetal healthcare.

New trimester-specific reference intervals for clinical biochemical tests in Taiwanese pregnant women-cohort of TMICS

Background

Because there are no published biochemical reference intervals (RI) for pregnant Taiwanese women, we used an established islandwide birth cohort, the Taiwan Maternal and Infant Cohort Study, to establish RIs for important biochemical parameters in women during their 3rd trimester in Taiwan. Additionally, we compared the differences in these biochemical parameters between early third trimester (weeks 28 to 31) and late third trimester (weeks 37 to 40) of pregnant women as well as the differences in them between the third trimester and after delivery.

Methods

Between 2012 and 2015, we recruited a total of 2,136 pregnant women from nine hospitals located in northern (n = 3), central (n = 3), southern (n = 2), and eastern Taiwan (n = 1) to receive regular prenatal health examinations during their third trimester (weeks 28 to 40). After exclusion, samples obtained from 993 eligible pregnant women were analyzed.

Results

There were increases in both lower and upper normal limits for blood neutrophil, thyroid profile (triiodothyronine (T3) and thyroxine (T4)), testosterone, estradiol, and progesterone and decreases for RBC, hemoglobin (Hb), alanine aminotransferase (ALT) and creatinine (Cr) during their third trimesters. Women in their late third trimester (n = 378) had higher median RBC, Hb, aspartate aminotransferase (AST), Cr, thyroid-stimulating hormone (TSH), testosterone, estradiol, and progesterone and lower median platelet and insulin, compared with those in their early third trimester (n = 490). Twenty-three of the women had both third trimester and post-pregnancy data. After delivery, the women had lower median AST, ALT, insulin, T3, T4, testosterone, estradiol, and progesterone and higher median Cr, free T4, FSH, and luteinizing hormone (LH), compared to their third trimesters.

Conclusions

Gestation-related changes in important biochemical parameters should be considered when evaluating clinical laboratory values in pregnant women.

Within-subject biological variation of activated partial thromboplastin time, prothrombin time, fibrinogen, factor VIII and von Willebrand factor in pregnant women

Background:

During pregnancy, interpretation of results from coagulation parameters can be difficult as the physiological changes that occur may affect the biochemical parameters. The aim of this study was to describe the normal course of five coagulation parameters in healthy pregnancies, and to estimate the within-subject biological variation (CVI).

Methods:

Blood samples were obtained every 4th week during pregnancy and three samples after delivery in 20 healthy women and every 4th week during a 40-week period in 19 healthy non-pregnant women. Activated partial thromboplastin time (APTT), prothrombin time (PT), PT International Normalized Ratio (INR), fibrinogen, factor VIII clot (FVIII:C) and von Willebrand factor antigen (vWF:Ag) were analyzed. The physiological changes during pregnancy were compensated by transformation into multiples of the median (MoM) and it is natural logarithm (lnMoM) in order to establish a kind of steady state, and CVIwas calculated from the standard deviation.

Results:

During pregnancy, APTT, PT and INR remained unchanged or decreased, depending upon the reagent used, while fibrinogen, FVIII:C and vWF:Ag increased gradually until delivery. The CVIin pregnancy were 2.2 and 3.0% for APTT, 2.3 and 2.6% for PT, 2.2 and 2.3% for INR, 7.2% for fibrinogen, 12.2% for FVIII:C and 11.3% for vWF:Ag, and corresponded with the CVIin non-pregnant women.

Conclusions:

Transformation of coagulation parameters in healthy pregnancies to MoM is a tool to establish a kind of steady state. Although there is a physiological change in these coagulation parameters during pregnancy, the CVIafter lnMoM transformation was comparable with the CVIof non-pregnant women.

Contemporary issues in the management of von Willebrand disease

Von Willebrand disease (VWD) is the most common inherited bleeding disorder. Bleeding scores in VWD, focused in particular on mucosal bleeding, can be very useful in the diagnosis and validation of different types of treatment. The results of an extended prospective study with a large amount of information on clinical phenotype and implications in treatment are reviewed in this article. Treatment of mucosal and joint bleeding in severe VWD remains difficult in some patients. Due to the lack of data on the use of prophylaxis in these patients it is difficult to establish optimal treatment regimens. An overview of the literature, with a focus on the ongoing PRO.WILL study, is provided here. Furthermore, understanding the changes in von Willebrand factor (VWF) levels during pregnancy is very important for establishing the optimal management strategy for pregnancy and delivery in women with VWD. A recently published prospective observational cohort study in women with and without VWD during the postpartum period provides important data that should allow the improvement of postpartum treatment protocols.

Estimates of Within-Subject Biological Variation of Protein C, Antithrombin, Protein S Free, Protein S Activity, and Activated Protein C Resistance in Pregnant Women

BACKGROUND

In pregnancy, interpretation of results from coagulation parameters can be difficult because of the procoagulant physiological changes. The aim of this study was to describe the course of 5 coagulation parameters (thrombophilia markers) in healthy pregnancies, and to estimate and compare the within-subject biological variation (CVI) of these parameters in healthy pregnant and nonpregnant women.

METHODS

Blood samples were obtained every 4th week during pregnancy and 3 samples after delivery in 20 healthy women and every 4th week during 40 weeks in 19 healthy nonpregnant women. Protein C (PC), antithrombin (AT), protein S free (PS free), protein S activity (PS activity), and activated protein C resistance (with factor V–depleted plasma) (APCR) were analyzed. Before the calculation of CVI, results were transformed into multiples of the median (MoM) and natural logarithm of MoM (lnMoM) to adjust for the physiological changes during pregnancy.

RESULTS

During pregnancy, PC results showed large variability, AT decreased slightly, and PS free and PS activity decreased significantly. Both activated partial thromboplastin time tests used to calculate APCR decreased, and the APCR ratio was constant. The CVI (lnMoM) in pregnancy were for PC 8.4%, for AT 3.8%, for PS free 11.5%, for PS activity 9.3%, and for APCR 0.5%, and similar to corresponding results in nonpregnant women.

CONCLUSIONS

Transformation of coagulation parameters in healthy pregnancies to lnMoM is a tool to establish a kind of steady state. Although there is a physiological change in PC, AT, and PS free and PS activity during pregnancy, the CVI was comparable with the CVI of nonpregnant women.

Obstetric bleeding among women with inherited bleeding disorders: a retrospective study

INTRODUCTION

Women with inherited bleeding disorders are at increased risk for bleeding complications during pregnancy and the postpartum period, particularly postpartum haemorrhage (PPH).

AIM

This retrospective study evaluates pregnancy management through the Inherited Bleeding Disorders Clinic of Southeastern Ontario, the clinical factors associated with pregnancy-related abnormal bleeding and assesses tranexamic acid use in the postpartum treatment of bleeding disorder patients.

METHODS

A chart review of 62 pregnancies, from 33 women, evaluated patient characteristics (age, haemostatic factor levels) and delivery conditions (mode of delivery, postpartum treatment) in relation to abnormal postpartum bleeding.

RESULTS

This cohort revealed increased risk of immediate PPH with increased age at delivery (mean age: 30.1 years with PPH, 26.5 years without PPH, P < 0.013), and birth by vaginal delivery (P < 0.042). Low von Willebrand factor (VWF) antigen or factor VIII (FVIII) in the third trimester was not associated with an increased risk of PPH; however, low VWF:RCo was associated with increased immediate PPH despite treatment with continuous factor infusion (P < 0.042). Women treated with tranexamic acid postpartum had less severe bleeding in the 6-week postpartum (P < 0.049) with no thrombotic complications.

CONCLUSIONS

This study contributes to the growing body of work aimed at optimizing management of bleeding disorder patients through pregnancy and the postpartum period, showing patients are at a higher risk of PPH as they age. Risk factors such as low third trimester VWF:RCo have been identified. Treatment with tranexamic acid in the postpartum period is associated with a reduced incidence of abnormal postpartum bleeding.

Antithrombin deficiency in pregnancy

We present a case of a 39-year-old, gravida 3 para 2, Chinese female with a history of inherited type 1 Antithrombin deficiency and multiple prior episodes of venous thromboembolism. She presented at 29+4 weeks' gestation with severe pre-eclampsia complicated by haemolysis, elevated liver enzymes and low platelet (HELLP) syndrome. She subsequently underwent an emergency caesarean section for non-reassuring fetal status, which was complicated by postpartum haemorrhage secondary to uterine atony, requiring a B-Lynch suture intraoperatively.

Antithrombin: anti-inflammatory properties and clinical applications

Many humoral and cellular components participate in bidirectional communication between the coagulation and inflammation pathways. Natural anticoagulant proteins, including antithrombin (AT), tissue factor pathway inhibitor, and protein C, suppress proinflammatory mediators. Conversely, inflammation blunts anticoagulant activity and, when uncontrolled, promotes systemic inflammation-induced coagulation, such as those that occur in disseminated intravascular coagulation and severe sepsis. This review discusses the mechanisms of action and clinical use of AT concentrate in critically ill patients and in the settings of perioperative anticoagulation management for surgery and obstetrics. AT is a serine protease inhibitor with broad anticoagulant activity and potent anti-inflammatory properties. In clinical conditions associated with hereditary or acquired AT deficiency, administration of AT concentrate has been shown to restore proper haemostasis and attenuate inflammation. Of note, AT modulates inflammatory responses not only by inhibiting thrombin and other clotting factors that induce cytokine activity and leukocyte-endothelial cell interaction, but also by coagulation-independent effects, including direct interaction with cellular mediators of inflammation. An increasing body of evidence suggests that AT concentrate may be a potential therapeutic agent in certain clinical settings associated with inflammation. In addition to the well-known anticoagulation properties of AT for the treatment of hereditary AT deficiency, AT also possesses noteworthy anti-inflammatory properties that could be valuable in treating acquired AT deficiency, which often result in thrombotic states associated with an inflammatory component.

Alterations of fibrin network structure mediated by dermatan sulfate

Dermatan sulfate (DS) is well-known for its anticoagulant activity through binding to heparin cofactor II (HCII) to enhance thrombin inhibition. It has also been reported that DS has a profibrinolytic effect. We have evaluated the effects of DS solutions (4-20 μg/mL) on the formation (by kinetic studies), structure (by electron microscopy and compaction assays) and lysis (with urokinase-type plasminogen activator) of plasma fibrin networks. The results showed that DS significantly prolonged the lag phase and decreased the fibrin formation rate and the optical density of the final networks versus control, in a concentration dependent way. DS-associated networks presented a minor network percentage compared with control, composed of lower number of fibers per field, which resulted significantly thinner and longer. Moreover, DS rendered gels more sensible to rupture by centrifugal force and more susceptible to lysis. When fibrin formation kinetic assays were performed with purified fibrinogen instead of plasma, in the absence of HCII, the optical density of final DS-associated networks was statistically lower than control. Therefore, a direct effect of DS on the thickness of fibers was observed. Since in all in vitro assays low DS concentrations were used, it could be postulated that the fibrin features described above are plausible to be found in in vivo thrombi and therefore, DS would contribute to the formation of less thrombogenic clots.

Prediction of preeclampsia by combining serum histidine-rich glycoprotein and uterine artery Doppler

BACKGROUND

Preeclampsia is associated with both maternal and perinatal morbidity and mortality. Histidine-rich glycoprotein (HRG) is a protein interacting with angiogenesis, coagulation, and inflammatory responses, processes known to be altered in preeclamptic pregnancies. Significantly lower levels of HRG have been demonstrated as early as in the first trimester in women later developing preeclampsia compared with normal pregnancies. The aim of this study was to investigate whether the combination of HRG and uterine artery Doppler ultrasonography can be used as a predictor of preeclampsia.

METHODS

A total of 175 women were randomly selected from a case-control study; 86 women had an uncomplicated pregnancy and 89 women later developed preeclampsia. Blood samples and pulsatility index (PI) were obtained from both cases and controls in gestational week 14.

RESULTS

HRG levels were significantly lower in women who developed preterm preeclampsia compared with controls, but not for women developing preeclampsia in general. PI was significantly higher in the preeclampsia group compared with controls, especially in preterm preeclampsia. The combination of HRG and PI revealed a sensitivity of 91% and a specificity of 62% for preterm preeclampsia.

CONCLUSIONS

The combination of HRG and uterine artery Doppler may predict preterm preeclampsia in early pregnancy.

Changes in the levels of factor VIII and von Willebrand factor in the puerperium

To determine changes in Factor VIII (FVIII) and von Willebrand Factor (VWF) in the first 3 days of the puerperium. A prospective study assessing FVIII clotting activity, VWF activity and antigen levels in 95 women (with singleton uncomplicated pregnancies) during labour and on days 1, 2 and 3 of the puerperium. There were no significant differences in FVIII, VWF:Ag and VWF:CB on days 1 and 2 of the puerperium compared with levels during labour. There was a significant decrease in VWF:Ag (P = 0.009) and VWF:CB (P = 0.04) on day 3. Age, ethnicity, duration of labour and mode of delivery did not have any significant effect on the changes in FVIII and VWF levels. The pregnancy induced increase in FVIII and VWF is maintained in the first 48 h after delivery. VWF levels start to decline on day 3 postdelivery.

Histidine-rich glycoprotein as an early biomarker of preeclampsia

BACKGROUND

Prediction of preeclampsia is of great interest and the coagulation system as well as the angiogenic pathway is known to be dysfunctional in preeclampsia. Histidine-rich glycoprotein (HRG) is a protein interacting with both these biological systems and the purpose of this prospective, longitudinal cohort study was to analyze whether there is a difference in circulating levels of HRG during pregnancy in women developing preeclampsia compared to normal healthy pregnancies. We furthermore wanted to evaluate whether HRG has the potential of being an early biomarker of preeclampsia.

METHODS

A cohort of healthy pregnant women (n = 469) was enrolled at gestational weeks 8-12. Plasma samples were collected at gestational weeks 10, 25, 28, 33, and 37 and analyzed with an enzyme-linked immunosorbent assay.

RESULTS

The levels of HRG decreased during pregnancy in all women, but the levels were significantly lower at gestational weeks 10, 25, and 28 in women who later developed preeclampsia than in normal pregnant women (P < 0.05, P < 0.05, and P < 0.05).

CONCLUSION

Our data indicates that HRG levels in plasma might be a possible biomarker already in gestational week 10 for prediction of later onset of preeclampsia in a low risk population.

Natural coagulation inhibitors and active protein c resistance in preeclampsia

INTRODUCTION

The etiology of preeclampsia is not fully established. A few studies have shown a relationship between natural coagulation inhibitors and preeclampsia.

OBJECTIVES

The purpose of this study was to investigate the status of natural coagulation inhibitors and active protein C resistance (APC-R) in preeclampsia.

PATIENTS AND METHODS

We studied 70 women with preeclampsia recruited consecutively and 70 healthy pregnant and 70 nonpregnant women as controls. Plasma protein C (PC), free protein S (fPS), antithrombin III (ATIII) and APC-R were evaluated.

RESULTS

ATIII values were found to be significantly lower in preeclamptic patients than in the control groups (p< 0.001). Nevertheless, there was no significant difference between the healthy pregnant and nonpregnant women groups (p=0.141). The fPS values of the preeclamptic and healthy pregnant groups were lower than that of the nonpregnant group (p< 0.001), and the fPS value of the preeclamptic pregnant women was lower than that of healthy pregnant women (p<0.001). The PC value of the preeclamptic pregnant women was lower than that of the control groups (p< 0.001). The PC value of the healthy pregnant women was lower than that of the nonpregnant women (p< 0.001). The mean APC activity values were lower in the preeclamptic patients than that of the control groups (p< 0.001, p< 0.001). The APC-R positivity rates of the preeclamptic groups were higher than that of the control groups (p<0.001).

CONCLUSIONS

This study demonstrated that ATIII, fPS, PC values and APC resistance were lower and APC-R positivity was higher in preeclamptic women than in normal pregnant and nonpregnant women.

Von Willebrand disease and other bleeding disorders in women: consensus on diagnosis and management from an international expert panel

Reproductive tract bleeding in women is a naturally occurring event during menstruation and childbirth. In women with menorrhagia, however, congenital bleeding disorders historically have been underdiagnosed. This consensus is intended to allow physicians to better recognize bleeding disorders as a cause of menorrhagia and consequently offer effective disease-specific therapies.

Human chorionic gonadatropin (hCG) during third trimester pregnancy

OBJECTIVE

Separate reference values were recently established for routine blood samples during last trimester pregnancy. Previously, these were based on blood samples from healthy men or non-pregnant women. Normal changes in variation in the levels of steroid hormones in the last weeks of pregnancy before delivery are also incompletely investigated. This study of the preterm hormone levels was carried out in the search for events leading to increased contractility that might occur in the predelivery weeks and potentially influence the initiation of delivery.

MATERIAL AND METHODS

Blood samples during pregnancy weeks 33, 36 and 39 as well as 1-3 h postpartum were collected from pregnant women (19-39 years, mean age 30) with at least one previous pregnancy without hypertension or pre-eclampsia. All women (n = 135) had had a vaginal delivery and spontaneous start of labour. The blood samples were analysed for serum hCG, oestradiol and progesterone. Postpartum, the values were retrospectively rearranged to correspond with the actual week before the day of delivery.

RESULTS

During the last trimester of normal pregnancy, a gradual increase was found in oestradiol (median 45980 to 82410 pmol/L), progesterone (median 341 to 675 nmol/L) and a gradual decrease in hCG (median 31833 to 19494 IU/L). Furthermore, a significant (p<0.03) decrease in hCG was found from the third to the second week before delivery, while oestradiol and progesterone continued to increase.

CONCLUSIONS

Hormone levels during third-trimester pregnancy have not previously been systematically investigated. Recent data suggest that hCG may have a role as an endogenous tocolytic in normal pregnancy by directly promoting relaxation of uterine contractions. In the present study a significant decrease in serum hCG level was found 2-3 weeks before the spontaneous start of labour. This might contribute to increasing the contractility in the uterine muscle and gradually initiate the onset of labour.

Hereditary and acquired antithrombin deficiency: epidemiology, pathogenesis and treatment options

Antithrombin is a glycoprotein critical to the regulation of coagulation. Its primary action is the inhibition of the activated coagulation factors IIa (thrombin) and Xa. In addition there is growing evidence to suggest that antithrombin also plays a role in the inhibition of inflammation within the environment of the vascular endothelium. Reduced plasma antithrombin may result from congenital deficiency or arise secondarily from a range of disorders such as liver dysfunction, premature infancy and sepsis, or as a result of interventions such as major surgery or cardiopulmonary bypass. Congenital antithrombin deficiency is the most clinically important of the inherited thrombophilias resulting in thrombosis in the majority of those affected. The challenge in managing these patients is preventing potentially life-threatening thrombosis, while minimising the equally significant risk of haemorrhage associated with long-term anticoagulation. This is achieved in the first instance by identifying high-risk episodes such as surgery, immobility and pregnancy for which prophylactic anticoagulation can be used in the short term. Prophylaxis for such periods is best provided by the use of low molecular weight heparin (LMWH) with substitution by or addition of antithrombin concentrate in particularly high-risk circumstances. In the case of pregnancy, antithrombin concentrate is often used around the time of birth when LMWH may increase the risk of post-partum haemorrhage. As patients with congenital antithrombin deficiency get older so their thrombotic risk gradually increases and for many patients long-term anticoagulation becomes unavoidable because of recurrent episodes of venous thromboembolism. There has been much interest in the role of antithrombin deficiency in the setting of sepsis and the critically ill patient where there is a clear correlation between severity of illness and degree of antithrombin reduction. It is not clear yet, however, to what extent the depletion of antithrombin affects the clinical condition of such patients. A number of trials have investigated the use of antithrombin as a treatment in the intensive care setting with the overall conclusion being that there is some benefit to its use but only if large supra-physiological doses are used. It has also become clear that the concurrent use of any form of heparin removes whatever benefit may be derived from antithrombin treatment in this setting. Until recently, antithrombin replacement was only available as a pooled plasma-derived product, which despite effective viral inactivation still carries an uncertain risk of transfusion transmitted infection. A recombinant antithrombin product now under investigation, and recently licensed in Europe, may provide a useful alternative treatment option.

Thromboembolism in pregnancy: recurrence and its prevention

Fifteen to 25% of thromboembolic events in pregnancy are recurrent events. Women with a history of thrombosis have a three- to fourfold increased risk of recurrence when they are pregnant compared with when they are not. The risks are even higher postpartum. The rate of recurrent venous thromboembolic events without anticoagulation is 2.4% to 12.2%, whereas the rate with anticoagulation is 0% to 2.4%. Because the rates of recurrent thromboembolism can be reduced with anticoagulation, women with a history of thrombosis who are not on lifelong anticoagulation will likely require anticoagulation during pregnancy, or at least during the postpartum period. Women who are already on lifelong warfarin for the prevention of recurrent venous thromboembolism should be counseled about the teratogenic effects of warfarin and offered the opportunity to be converted to heparin before conception. During pregnancy, low-molecular-weight heparin, with fewer side effects and a longer half-life, is generally preferred over unfractionated heparin. Unfractionated heparin with its shorter half-life is generally preferred around the time of delivery. Women on antiplatelet medication for prevention of arterial thromboembolism may be converted to low-dose aspirin after conception and supplemented with low-dose heparin or low-molecular-weight heparin during pregnancy. Because current recommendations rely on case series and expert opinion, additional studies including randomized trials might enhance our ability to prevent recurrent thromboembolism in pregnancy.

More than menorrhagia: a review of the obstetric and gynaecological manifestations of bleeding disorders

In women, menorrhagia may be the most common manifestation of a bleeding disorder, but it is not the only reproductive tract abnormality that women with bleeding disorders experience. Women with bleeding disorders appear to be at an increased risk of developing haemorrhagic ovarian cysts and possibly endometriosis. As they grow older, they may be more likely to manifest conditions, which present with bleeding such as fibroids, endometrial hyperplasia and polyps. Women with bleeding disorders are more likely to undergo a hysterectomy and are more likely to have the operation at a younger age. During pregnancy, they may be at greater risk of miscarriage and bleeding complications. At the time of childbirth, women with bleeding disorders appear to be more likely to experience postpartum haemorrhage, particularly delayed or secondary postpartum haemorrhage. Vaginal or vulvar haematomas, extremely rare in women without bleeding disorders, are not uncommon. While women with bleeding disorders are at risk for the same obstetrical and gynaecological problems that affect all women, they appear to be disproportionately affected by conditions that manifest with bleeding.

Haemostasis in normal pregnancy: a balancing act?

Pregnancy is a risk factor for venous thrombosis and the incidence of venous thromboembolism during normal pregnancy is 6-fold higher during pregnancy than in the general female population of child-bearing age. This incidence is, however, remarkably low given the increases in markers of haemostatic activation observed during normal pregnancy. During normal healthy pregnancy there are substantial changes in the haemostatic system, many of which are procoagulant and supposed to be in preparation for the haemostatic challenge of delivery. Normal haemostasis requires a balance between coagulation and fibrinolysis to maintain the integrity of the vasculature, and complex physiological changes are evident during pregnancy which appear to ensure a constant coagulation/fibrinolysis balance. This balance is maintained, at least partly, by an increase in fibrinolytic activity, but decreases in other factors such as factor XI and monocyte tissue factor expression may also serve to counterbalance procoagulant changes.

Changes in haemostasis during normal pregnancy

OBJECTIVES

(1) To study the changes in the haemostatic variables during normal pregnancy, and (2) to compare them with the corresponding variables in a control group of nonpregnant women.

SETTING

University Hospital.

SUBJECTS

The study involves two groups of women: pregnant women (in 35th-40th gestational weeks (GW)) (N = 35) and a control group of nonpregnant women (N = 35).

METHODS

We examined the global tests, the variables relating to coagulation and fibrinolysis and the group of natural inhibitors of coagulation, and compared them between the two groups.

RESULTS

The pregnant women had statistically significantly higher values for: prothrombin time (PT) (P < 0.0001), thrombin time (TT) (P < 0.0001), fibrinogen (P < 0.0001), activity of factor VII (P < 0.0001), factor X (P < 0.0001) and alpha2-antiplasmin (P < 0.002), plasma concentration of D-dimer (plsDD) (P < 0.0001) and activity of heparin cofactor II (HCII) (P < 0.002). They had statistically significantly lower activity of protein C (PrC) (P < 0.0001) and of total protein S (TPrS) (P < 0.0001).

CONCLUSION

During normal pregnancy the activation of coagulation is counterbalanced by the activation of fibrinolysis, which maintains the haemostatic balance.