Intermediate-dose versus low-dose low-molecular-weight heparin in pregnant and post-partum women with a history of venous thromboembolism (Highlow study): an open-label, multicentre, randomised, controlled trial.

BACKGROUND: Pregnancy-related venous thromboembolism is a leading cause of maternal morbidity and mortality, and thromboprophylaxis is indicated in pregnant and post-partum women with a history of venous thromboembolism. The optimal dose of low-molecular-weight heparin to prevent recurrent venous thromboembolism in pregnancy and the post-partum period is uncertain. METHODS: In this open-label, randomised, controlled trial (Highlow), pregnant women with a history of venous thromboembolism were recruited from 70 hospitals in nine countries (the Netherlands, France, Ireland, Belgium, Norway, Denmark, Canada, the USA, and Russia). Women were eligible if they were aged 18 years or older with a history of objectively confirmed venous thromboembolism, and with a gestational age of 14 weeks or less. Eligible women were randomly assigned (1:1), before 14 weeks of gestational age, using a web-based system and permuted block randomisation (block size of six), stratified by centre, to either weight-adjusted intermediate-dose or fixed low-dose low-molecular-weight heparin subcutaneously once daily until 6 weeks post partum. The primary efficacy outcome was objectively confirmed venous thromboembolism (ie, deep-vein thrombosis, pulmonary embolism, or unusual site venous thrombosis), as determined by an independent central adjudication committee, in the intention-to-treat (ITT) population (ie, all women randomly assigned to treatment). The primary safety outcome was major bleeding which included antepartum, early post-partum (within 24 h after delivery), and late post-partum major bleeding (24 h or longer after delivery until 6 weeks post partum), assessed in all women who received at least one dose of assigned treatment and had a known end of treatment date. This study is registered with ClinicalTrials.gov, NCT01828697, and is now complete. FINDINGS: Between April 24, 2013, and Oct 31, 2020, 1339 pregnant women were screened for eligibility, of whom 1110 were randomly assigned to weight-adjusted intermediate-dose (n=555) or fixed low-dose (n=555) low-molecular-weight heparin (ITT population). Venous thromboembolism occurred in 11 (2%) of 555 women in the weight-adjusted intermediate-dose group and in 16 (3%) of 555 in the fixed low-dose group (relative risk [RR] 0·69 [95% CI 0·32-1·47]; p=0·33). Venous thromboembolism occurred antepartum in five (1%) women in the intermediate-dose group and in five (1%) women in the low-dose group, and post partum in six (1%) women and 11 (2%) women. On-treatment major bleeding in the safety population (N=1045) occurred in 23 (4%) of 520 women in the intermediate-dose group and in 20 (4%) of 525 in the low-dose group (RR 1·16 [95% CI 0·65-2·09]). INTERPRETATION: In women with a history of venous thromboembolism, weight-adjusted intermediate-dose low-molecular-weight heparin during the combined antepartum and post-partum periods was not associated with a lower risk of recurrence than fixed low-dose low-molecular-weight heparin. These results indicate that low-dose low-molecular-weight heparin for thromboprophylaxis during pregnancy is the appropriate dose for the prevention of pregnancy-related recurrent venous thromboembolism. FUNDING: French Ministry of Health, Health Research Board Ireland, GSK/Aspen, and Pfizer.

Induction of labor and nulliparity: A nationwide clinical practice pilot evaluation.

INTRODUCTION: Induction of labor has become an increasingly common obstetric procedure, but in nulliparous women or women with a previous cesarean section, it can pose a clinical challenge. Despite an overall expansion of medical indications for labor induction, there is little international consensus regarding the criteria for induction, or for the recommended methods among nulliparous women. In this light, we assessed variations in the practice of induction of labor among 21 birth units in a nationwide cohort of women with no prior vaginal birth. MATERIAL AND METHODS: We carried out a prospective observational pilot study of women with induced labor and no prior vaginal birth, across 21 Norwegian birth units. We registered induction indications, methods and outcomes from 1 September to 31 December 2018 using a web-based case record form. Women were grouped into "Nulliparous term cephalic", "Previous cesarean section" and "Other Robson" (Robson groups 6, 7, 8 or 10). RESULTS: More than 98% of eligible women (n=1818) were included and a wide variety of methods was used for induction of labor. In nulliparous term cephalic pregnancies, cesarean section rates ranged from 11.1% to 40.6% between birth units, whereas in the previous cesarean section group, rates ranged from 22.7% to 67.5%. The indications "large fetus" and "other fetal" indications were associated with the highest cesarean rates. Failed inductions and failure to progress in labor contributed most to the cesarean rates. Uterine rupture occurred in two women (0.11%), both in the previous cesarean section group. In neonates, 1.6% had Apgar <7 at 5 minutes, and 0.4% had an umbilical artery pH <7.00. CONCLUSIONS: Cesarean rates and applied methods for induction of labor varied widely in this nationwide cohort of women without a prior vaginal birth. Neonatal outcomes were similar to those of normal birth populations. Results could indicate the need to move towards more standardized induction protocols associated with optimal outcomes for mother and baby.

Onset of labor and use of analgesia in women using thromboprophylaxis with 2 doses of low-molecular-weight heparin: insights from the Highlow study.

BACKGROUND: Peripartum management of women using low-molecular-weight heparin (LMWH) varies widely. Minimum time intervals are required between LMWH injection and neuraxial procedure, and they differ by dose. OBJECTIVES: The objective of this study was to describe the onset of labor and use of analgesia in women using LMWH and to compare practices between intermediate-dose and low-dose LMWH. METHODS: In the Highlow study (NCT01828697), 1110 women were randomized to intermediate-dose or low-dose LMWH and were instructed to discontinue LMWH when labor commenced unplanned or 24 hours prior to planned delivery. The required time interval since last injection to receive a neuraxial procedure was ≥24 hours for intermediate-dose LMWH or ≥12 hours for low-dose LMWH. RESULTS: In total, 1018 women had an ongoing pregnancy for ≥24 weeks. Onset of labor was spontaneous in 198 of 509 (39%) women on intermediate-dose LMWH and in 246 of 509 (49%) on low-dose LMWH. With unplanned onset, a neuraxial procedure was performed in 37% on intermediate-dose and in 48% on low-dose LMWH (risk difference -11%, 95% CI -20% to -2%). Based on time interval, 61% on intermediate-dose and 82% on low-dose LMWH were eligible for a neuraxial procedure. With planned onset, 68% on intermediate-dose and 66% on low-dose LMWH received a neuraxial procedure, whereas 81% and 93%, respectively, were eligible for a neuraxial procedure (risk difference -13%, 95% CI -18% to -8%). CONCLUSION: With spontaneous onset of labor, neuraxial procedures were performed less often in women using intermediate-dose LMWH. Irrespective of onset, fewer women on intermediate-dose LMWH than those on low-dose LMWH were eligible for neuraxial procedures based on required time intervals since the last LMWH injection.

Candidate gene polymorphisms and the risk for pregnancy-related venous thrombosis.

Venous thrombosis (VT) is one of the leading causes of maternal death in the western world, but the genetic causes of pregnancy-related VT are insufficiently understood. The aim of this study was to investigate the association between common genetic variations in candidate genes and pregnancy-related VT. We undertook a hospital based case-control study of women with VT during pregnancy or puerperium; controls were women giving birth without having VT. Single nucleotide polymorphisms (SNPs) were selected in 49 pre-specified candidate genes involved in coagulation, inflammation, and hormonal metabolism in 313 cases and 353 controls. We found new associations between SNPs and total pregnancy-related VT in the genes encoding coagulation factors V and VIII, and p-selectin. Additional new associations between SNPs and antenatal VT were found in the genes encoding the epidermal growth factor receptor, the pregnane X receptor, and protein S. Of 21 SNPs previously associated with thrombotic disease, rs2289252 in F11 and rs3917643 in F3 were associated with pregnancy-related VT, while rs4524 in F5 was associated with antenatal VT.

Treatment of Homozygous Type II Antithrombin Heparin-Binding Site Deficiency in Pregnancy.

Pregnancy is associated with an increased risk of venous thromboembolism (VTE). Previous VTE and severe thrombophilia are important risk factors. Our case was a 36-year-old woman, gravida 6, para 0, with antithrombin (AT) deficiency caused by a homozygous mutation in the heparin-binding site (HBS). Her history included seven prior VTEs, three early and two late pregnancy losses. She was prophylactically treated with both human plasma-derived AT concentrate (hpATC) and low molecular weight heparin (LMWH), resulting in a successful 6th pregnancy and a healthy live born baby. There is limited evidence and guidance on the management of AT deficiency in pregnancy. Dosing and monitoring of anticoagulants, alone or together with hpATC, must be based on individual risk assessment. The severity of clinical manifestations varies with the type of AT deficiency. Characterization of the AT mutation may aid in the decision-making process and optimize pregnancy outcomes.

The structure and utility of the placental pathology report.

The placenta is one of the most exciting organs. It is dynamic; its morphology and function continuously develop and adjust over its brief life span. It mediates the physiology of two distinct yet highly interconnected individuals. The pathology that develops in the placenta, and the adaptations the placenta undergoes to mitigate this pathology, may influence the later life health of the mother and baby (Circ Res, 116, 2015, 715; Hum Reprod Update, 17, 2011, 397; Nutr Rev 71, 2013, S88; Placenta, 36, 2015, S20). Pathological placenta examination may reveal macroscopic and microscopic patterns that provide valuable information to the obstetricians, neonatologists, and pediatricians caring for the family. The placenta often plays a key role in understanding adverse fetal outcomes such as hypoxic brain injury, cerebral palsy, fetal growth restriction, stillbirth, and neonatal death (Placenta, 35, 2014, 552; Placenta, 52, 2017, 58; Placenta, 30, 2009, 700; Obstet Gynecol, 114, 2009, 809; Clin Perinatol, 33, 2006, 503; Pediatr Dev Pathol, 11, 2008, 456; Arch Pathol Lab Med, 124, 2000, 1785). Moreover, it may help to understand the pathophysiology of pregnancy, improve management of subsequent pregnancies, and assist in medicolegal assessment. Placental pathologic examination may even provide evidence of susceptibility to adult-onset diseases such as diabetes (Pediatr Dev Pathol, 6, 2003, 54; Diabetes Metab, 36, 2010, 682; BJOG, 113, 2006, 1126; Int J Gynaecol Obstet, 104, 2009, S25; Zentralbl Gynakol, 97, 1975, 875). Pathologic examination of the placenta may thus be of tremendous value, particularly for those women experiencing an adverse pregnancy outcome. However, this potential utility may be entirely wasted, if the findings are not communicated in an effective manner to the appropriate clinicians. An optimized, readily understandable report of pathological findings is essential for clinical utility.

Long-term mortality and incidence of cancer after pregnancy-related venous thrombosis: results of a population-based cohort study.

The long-term mortality and incidence of cancer after pregnancy-related venous thrombosis (VT) is not known. In this population-based cohort study we identified women with a first-ever pregnancy-related VT (cases, n = 557)) from 18 Norwegian hospitals during 1990-2003. Hospital controls (n = 1214) were selected among women who gave birth at the same time as a case. All participants were linked to the Norwegian Cause of Death Registry and to the Cancer Registry of Norway in 2012. The general age-adjusted Norwegian female population was used as a second control group to calculate the standardized mortality ratio (SMR) and the standardized incidence ratio (SIR) for cancer. Ten cases (1.8%) and seven hospital controls (0.6%) died during follow-up. Mortality was 3.2 times higher among cases as compared with hospital controls when adjusted for age (HR 3.2, 95% confidence interval 1.2-8.5, p = 0.018). The SMR for the first year of follow-up was 18.8 (7.8-45.3) and for the rest of the study period 0.9 (0.4-2.0). Fifteen cases (2.7%) and 13 hospital controls (1.1%) were diagnosed with cancer after index pregnancy. The incidence of cancer was 2.6 times higher among cases compared with hospital controls when adjusted for age (HR 2.6, 1.3-5.6, p = 0.011), but compared with the age-adjusted female population in Norway there was no excess risk of cancer (SIR 1.0, 95% CI 0.6-1.7). Mortality and incidence of cancer after pregnancy-related VT was low. Both were increased among cases compared with hospital controls, but not when compared with the general population, except for mortality during the first year after VT.

The association of inherited thrombophilia and intrauterine fetal death: a case-control study.

Inherited thrombophilias are probably associated with placenta-mediated pregnancy complications, but the strength of the association between inherited thrombophilias and intrauterine fetal death after 22 gestational weeks varies due to small sample size and different methodologies used across studies. The objective of the present study was to investigate the association of inherited thrombophilia and intrauterine fetal death in a case-control design. We studied 105 women with a history of intrauterine fetal death after 22 gestational weeks and 262 controls with live births. We investigated the prevalence of the factor V Leiden (F5 rs6025) and prothrombin gene G20210A (F2 rs1799963) polymorphisms, and antithrombin, protein C and protein S deficiencies, and their association with intrauterine fetal death. Results were presented as percentages and odds ratios (ORs) with 95% confidence intervals (CIs). A total of 18.4% of cases and 11.8% of controls were positive for at least one inherited thrombophilia (OR 1.7; 95% CI 0.9-3.1). The prothrombin gene G20210A polymorphism (OR 4.0; 95% CI 1.1-14.4), but not the factor V Leiden polymorphism, or antithrombin, protein C or protein S deficiencies, was associated with intrauterine fetal death after 22 weeks of gestation. Compared with women with live births only, women with a history of intrauterine fetal death after 22 gestational weeks were significantly more often carriers of the prothrombin gene G20210A polymorphism.