Foetal Growth Restriction in Children with Prothrombotic Risk Factors

Maternal and Newborn Characteristics-A Comparison between Healthy and Thrombophilic Pregnancy

A thrombophilic woman is more likely to experience difficulties during pregnancy, difficulties that will also affect the development of the newborn. This study aims to compare maternal and newborn characteristics between healthy and thrombophilic pregnancy. The following characteristics were analysed: maternal characteristics (BMI- body mass index, haemostasis parameters, thrombophilia-specific treatment) and newborn characteristics (gestational period, birth weight, the Apgar score). This follow-up study spanning five years, from 2018 to 2022, focuses on a cohort of 500 women who underwent delivery hospitalization in the western region of Romania. The maternal characteristics influence the newborn: the greater the weight of the mother with thrombophilia, the more the chances that the fetus will have a lower birth weight; increasing the dose of LMWH (low molecular weight heparin), connected with the necessity to control the homeostasis parameters, the more likely the fetus will be born with a lower birth weight. A pregnant woman with thrombophilia, treated appropriately, having a normal weight, and not presenting other risk factors independent of thrombophilia, will have a newborn with characteristics similar to a healthy pregnant woman.

Symptomatic aortic thrombosis in a preterm neonate

Symptomatic aortic thrombosis is a devastating condition in the neonatal intensive care unit (NICU), which is now increasingly being diagnosed with the availability of bedside ultrasound. Early intervention can go a long way towards preventing adverse outcomes. In our case, a preterm, very low birth weight, growth-restricted baby developed aortic thrombosis with hypertensive emergency and later limb-threatening ischaemia, which usually requires thrombolysis. However, due to the parents' reservations, he was given only therapeutic anticoagulation (with closely monitored activated partial thromboplastin time targets), which resulted in complete thrombus resolution. A multidisciplinary team approach was followed, and early detection with frequent monitoring led us to a favourable outcome.

Factor V Leiden is associated with pre-eclampsia but not with fetal growth restriction: a genetic association study and meta-analysis

BACKGROUND

Adverse pregnancy outcomes have been related to environmental and/or genetic factors. Of interest are genes associated with the clotting system as any perturbation in the balance of thrombotic and thrombolytic cascades could affect the placental circulation and hence the viability of the developing fetus. Several previous reports using relatively small numbers of cases and controls have suggested that there is a relationship between poor pregnancy outcomes and two polymorphisms, one in the factor V gene, the 1691G to A change (rs6025) located on chromosome 1q23 (factor V Leiden, FVL), and the other in the prothrombin gene, 20210G to A change (rs1799963) on chromosome 11p11-q12 (PT). These results, however, are conflicting.

METHODS

We genotyped 6755 mother/infant pairs from the Avon Longitudinal Study of Parents and Children (ALSPAC) to determine whether maternal or fetal FVL or PT, either alone or in combination, are associated with fetal growth restriction (FGR) or pre-eclampsia (PE). We also added the present results to previous cohort studies using meta-analysis.

RESULTS

Smoking, primiparity and lower body mass index (BMI) were all associated with FGR, but neither maternal nor fetal FVL or PT, singly or in combination, were associated with FGR in the ALSPAC cohort. Meta-analysis confirmed the lack of association between maternal FVL and FGR with a pooled odds ratio (OR) of 1.15 [95% confidence interval (CI) 0.95-1.39]. High BMI, primiparity, diabetes and chronic hypertension were all associated with pre-eclampsia. Combining ALSPAC results with previous studies in ameta-analysis indicated that maternal FVL is significantly associated with pre-eclampsia, with a pooled OR of 1.49 (95% CI 1.13-1.96).

CONCLUSION

Neither maternal nor fetal FVL or PT, singly or in combination, are associated with FGR; this contradicts previous case-control studies and meta-analyses based on these studies. In a meta-analysis of all published cohort studies to date, maternal FVL appears to increase the risk of pre-eclampsia by almost 50%. This result is robust, homogeneous and does not appear to be affected by publication bias.

Decreased maternal protein S activity is associated with fetal growth restriction

INTRODUCTION

Protein S (PS) activity has been shown to decrease during normal pregnancy. The aim of this study was to determine any correlation between decreased maternal PS activity and fetal growth restriction (FGR).

METHODS

We carried out a retrospective study of maternal PS activity and complement 4b-binding protein (C4BP) concentration in 102 patients with FGR and 58 patients with fetuses that had normal growth. Among pregnancies affected by FGR, 14 diagnoses were made in the second trimester and 88 in the third trimester. Patients whose fetuses had normal growth were matched with FGR subjects for maternal age and gestational age at sampling (29 cases each in the second and third trimester).

RESULTS

Mean PS activity of the control group in the third trimester was significantly lower than in the second trimester (56.5+/-16.5% vs 35.8+/-13.8%). PS activity in women with FGR was significantly decreased in both the second trimester (36.6+/-13.2%) and third trimester (30.2+/-12.2%) compared with control group levels. Plasma concentrations of C4BP for the control group were significantly higher in the third trimester than in the second trimester (90.5+/-17.5% vs 81.1+/-13.6%). However, in women with FGR, plasma C4BP concentrations in both the second trimester (84.0+/-14.8%) and the third trimester (86.0+/-17.7%) were comparable with concentrations of the control group.

CONCLUSIONS

Maternal PS activity decreased as normal pregnancies progressed but decreased over time in cases with FGR. Excessive decreases in PS activity during pregnancy could contribute to development of FGR.

Placenta and fetal growth restriction

The placenta, as the vector for all maternal-fetal oxygen and nutrient exchange, is a principal influence on birthweight. Placental weight summarizes laterally expanding growth of the chorionic disc, and villous arborization yielding the nutrient exchange surface. These different growth dimensions alter fetoplacental weight ratio and ponderal index, and thus may modify placental functional efficiency. The placenta may show a range of histopathologies, some of which are also associated with fetal growth restriction. Different fetal intrinsic abilities to compensate for gross and histo-pathology may clarify the imperfect relationships between fetal growth and both intrauterine pathology, and the long-term health risks associated with poor fetal growth.

Kidney gene expression analysis in a rat model of intrauterine growth restriction reveals massive alterations of coagulation genes

In this study, low birth weight was induced in rats by feeding the dams with a low-protein diet during pregnancy. Kidneys from the fetuses at the end of gestation were collected and showed a reduction in overall and relative weight, in parallel with other tissues (heart and liver). This reduction was associated with a reduction in nephrons number. To better understand the molecular basis of this observation, a transcriptome analysis contrasting kidneys from control and protein-deprived rats was performed, using a platform based upon long isothermic oligonucleotides, strengthening the robustness of the results. We could identify over 1800 transcripts modified more than twice (772 induced and 1040 repressed). Genes of either category were automatically classified according to functional criteria, making it possible to bring to light a large cluster of genes involved in coagulation and complement cascades. The promoters of the most induced and most repressed genes were contrasted for their composition in putative transcription factor binding sites, suggesting an overrepresentation of the AP1R binding site, together with the transcription induction of factors actually binding to this site in the set of induced genes. The induction of coagulation cascades in the kidney of low-birth-weight rats provides a putative rationale for explaining thrombo-endothelial disorders also observed in intrauterine growth-restricted human newborns. These alterations in the kidneys have been reported as a probable cause for cardiovascular diseases in the adult.

Fetal and Neonatal Thrombophilia

Thrombophilia of the fetus and neonate may contribute to higher prevalence of perinatal thrombosis. Due to the potential interaction between thrombophilic risk factors of the neonate and maternal thrombophilia and placental vasculopathy, we recommend thrombophilia assessment be performed in any child and in the mother in case of perinatal thrombosis. Further attention and larger prospective studies are required to establish the role of thrombophilic risk factors in the pathogenesis of any other perinatal complications.

Associations between fetal inherited thrombophilia and adverse pregnancy outcomes

OBJECTIVE

The purpose of this study was to investigate associations between fetal inherited thrombophilia and adverse pregnancy outcomes, including pregnancy-induced hypertensive disorders (PIHD), antepartum hemorrhage (APH), small-for-gestational age <10th percentile (SGA), and preterm birth (PTB).

STUDY DESIGN

Seven hundred and seventeen cases and 609 controls were genotyped for Factor V Leiden (FVL, G1691A), Prothrombin gene mutation (PGM, G20210A), and Methylenetetrahydrofolate reductase (MTHFR) C677T and MTHFR A1298C using DNA from newborn screening cards.

RESULTS

For babies born <28 weeks' gestation, PGM was associated with an increased risk of SGA (OR 6.40, 95%CI 1.66-24.71) and APH with SGA (OR 6.35, 95%CI 1.63-24.75). Homozygous MTHFR A1298C was associated with an increased risk of SGA for babies born 28-31 weeks gestation (OR 4.00, 95%CI 1.04-15.37), and with APH and SGA for babies born <32 weeks' gestation (OR 3.57, 95%CI 1.09-11.66). Homozygous MTHFR C677T was associated with a reduced risk of PTB and SGA (OR 0.52, 95%CI 0.28-0.96) for babies born 32 to 36 weeks' gestation. Homozygous FVL decreased the risk of PTB <32 weeks' gestation (OR 0.55, 95%CI 0.31-0.98).

CONCLUSION

Fetal thrombophilic polymorphisms may be related to adverse pregnancy outcomes, in particular SGA.

Factor V Leiden mutation: a contributory factor for cerebral palsy?

Fifty-seven children with cerebral palsy (CP) and imaging evidence of vascular thrombosis (study group) and 167 children with CP and other imaging finds (control group)were selected. Sixty-one per cent of the study group were male and 53 (93%) had spastic hemiplegia compared with the control group, of whom 55% were male and 54 (32%) had a diagnosis of spastic hemiplegia. Mean age was 5 years 11 months (SD 5y 1mo) for the study group and 7 years 7 months (SD 4y 7mo) for the control group. Blood spots on Guthrie cards or buccal swabs were used to test both groups and their mothers for the factor V Leiden (fVL) mutation, which predisposes carriers to thrombophilia. Mothers were interviewed to gather antenatal, perinatal, demographic, and socio-economic data. The frequency of the fVL mutation in children with evidence of vascular thrombosis and their mothers was not statistically different from the frequency in children with CP with other imaging findings and their mothers. The frequency of the fVL mutation was significantly higher than the expected population frequency of 4% in the study group (10.5%, p=0.012) and in mothers of the control group (7.2%, p=0.036).

Intraventricular haemorrhage in very-low-birthweight preterm infants: association with low prothrombin activity at birth

AIM

To determine the occurrence of intraventricular haemorrhage (IVH) and its association with coagulation factors at birth in preterm neonates born before 30 wk gestation.

METHODS

38 neonates (median gestational age 27 wk, range 24-29 wk; median birthweight (BW) 933 g, range 515-1760 g) admitted to the neonatal intensive care unit were studied. Blood samples for coagulation factors were taken within 2 h after birth. The first cranial ultrasonographic examination was performed within the first 3 d. The occurrence of IVH was tested statistically by the Mann-Whitney U-test for association with the activity of coagulation factors and clinical variables.

RESULTS

Thirteen IVHs occurred within the first 3 d of life. IVH was associated with BW <1000 g (p=0.012), low mean blood pressure within the first 2 d (p=0.026), gestational age <27 wk (p=0.054), low Apgar scores (<7) at 1 min (p=0.078) and intrauterine growth restriction (p=0.072). At birth (samples drawn with a median of first 36 min of life), infants with subsequent IVH had statistically significantly lower prothrombin (factor II) activity (p=0.024) than infants without IVH.

CONCLUSION

The measured low prothrombin may have been affected by a prior bleeding event. Nevertheless, preterm infants with low prothrombin activity may be susceptible to IVH, or to the progression of it, if left undiagnosed.

Genetic risk factors associated with thrombosis in children with congenital neurologic disorders

Thromboembolic events during the perinatal period are responsible for irreversible brain damage owing to cerebral hypoxia and neuronal necrosis. We investigated the presence of thrombophilia risk factors in children with congenital neurologic disorders. Nineteen children (9 males and 10 females), aged 1 to 14 years (median 4.5 years), who had presented with symptoms and signs of congenital neurologic disorders were studied. Thirty-five age-matched healthy children recruited from the same geographic area served as controls. Three patients of 19 (15.8%) were carrying the factor V Leiden mutation compared with 2 children among the controls (5.7%). One patient was heterozygous for the prothrombin G20210A variant (5.2%) compared with one child who was heterozygous among the controls. Three patients were homozygous (15.8%) and 11 were heterozygous (57.9%) for the C677T 5,10-methylenetetrahydrofolate reductase gene mutation compared with 4 (11.5%) and 18 (51.4%), respectively, among the controls. Three patients of 19 (15.8%) were carrying more than one mutation. We found 18 mutations in 79% (15/19) of the patients and 25 mutations in 69% (24/35) of the healthy children. Among the individuals carrying the homozygous 677TT 5,10-methylenetetrahydrofolate reductase genotype, we found 7 mutations in 32% (6/19) of the patients and 7 mutations in 20% (7/35) of the healthy children (P > .05). In one patient, lupus anticoagulant and antiphospholipid antibodies of IgG isotype were detected. Reduced activities of protein C, protein S, or antithrombin III were not observed in either the patient or the control group. Although, among our cases, we found some well-known risk factors associated with thrombosis in adults, the pathogenesis of these clinical entities remains obscure.

A systematic review of the association between factor V Leiden or prothrombin gene variant and intrauterine growth restriction

OBJECTIVE

The purpose of this study was to conduct a systematic review of the literature of studies that examined the association between factor V Leiden and/or prothrombin gene variant and intrauterine growth restriction.

STUDY DESIGN

This systematic review of studies assesses the association between factor V Leiden and/or prothrombin gene variant and intrauterine growth restriction.

RESULTS

Ten case-control studies fulfilled the selection criteria for inclusion in the meta-analysis. There was a significant association between factor V Leiden and intrauterine growth restriction (odds ratio, 2.7; 95% CI, 1.3-5.5) and prothrombin gene variant and intrauterine growth restriction (odds ratio, 2.5; 95% CI, 1.3-5.0). Five cohort studies were identified in the systematic review; 3 studies were prospective (2 full publications), and 2 studies were retrospective (1 full publication). Combining the 2 full publication prospective studies yields a summary relative risk of 0.99 (95% CI, 0.5-1.9).

CONCLUSION

This meta-analysis of case-control studies suggests that the factor V Leiden and prothrombin gene variant both confer an increased risk of giving birth to an intrauterine growth restricted infant, although this may be driven by small, poor-quality studies that demonstrated extreme associations. Large well-conducted prospective cohort studies are required to determine definitively whether an association between thrombophilia and intrauterine growth restriction is present.

High frequency of congenital thrombophilia in women with pathological pregnancies?

The obstetrical complications preeclampsia, intrauterine growth restriction (IUGR), placental abruption and fetal loss are major causes of maternal and fetal morbidity and mortality. Much recent research has focused on to what extent congenital thrombophilia contributes to these obstetrical complications. Combined with the hypercoagulable state of pregnancy, thrombophilia has the potential to induce placental thrombosis and cause placental insufficiency with subsequent obstetrical complications. This article aims to review and discuss published clinical studies of the relationship between congenital thrombophilia and preeclampsia, IUGR, placental abruption and fetal loss. In addition, the few published clinical trials of prophylactic antithrombotic treatment to prevent severe obstetrical complications in thrombophilic women are discussed. The studies have shown variable results evaluated mainly as a result of the limited number of case reports published. However, the strongest association was found to be between congenital thrombophilia and preeclampsia and late fetal loss. Early fetal loss was not found to be associated with congenital thrombophilia. At present, the question remains open as to whether IUGR and placental abruption is directly associated with thrombophilia or mediated through preeclampsia. In conclusion, the associations between congenital thrombophilia and preeclampsia, IUGR, placental abruption and fetal loss only reaches evidence grade 4. Present recommendations and clinical guidelines are thus based on weak scientific proof.

Thrombophilia and pregnancy complications

OBJECTIVE

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

RESULTS

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

CONCLUSION

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

Factor V Leiden and perioperative risk

Factor V Leiden (FVL) is the most common known inherited cause of thrombophilia; it is present in approximately 5% of the Caucasian population. Although the risk of venous thrombosis associated with this polymorphism in various medical settings is well described, its effect on perioperative risk is only beginning to be explored. Specifically, there are few studies addressing the potential risks of FVL in the surgical population, in which both hemorrhagic and thrombotic complications convey substantial clinical and economic significance. There are speculations and unproven hypotheses regarding FVL in this population, and these therefore highlight the need to comprehensively address this issue. This review will describe the physiology of the FVL mutation, briefly clarify its risk in the nonsurgical setting, and assess current data regarding FVL in noncardiac and cardiac surgery. Finally, a summary of current clinical evidence and a plan for more detailed investigation of this potentially significant risk factor will be proposed.

Thrombophilia and fetal growth restriction

OBJECTIVE

Genetic thrombophilia may represent a new risk factor for obstetrical complications. The aim of the study was to determine which subgroups may be associated with genetic thrombophilia for small for gestational age infants (SGA).

METHODS

A case-control study was performed in three different maternity wards in Normandy. Cases (n=203) were women who had pregnancies complicated by unexplained SGA infants defined as a birth weight below the 3rd centile and control subjects (n=203) were women who had infants with birth weight > or =10th centile. Patients were tested in the immediate postpartum period and 2 months later for factor V Leiden mutation, and prothrombin 20210A mutation. Frequencies of these mutations were observed in different subgroups of SGA infants depending on pregnancy or neonatal outcomes usually associated with intrauterine growth restriction (IUGR), and were then compared with the overall prevalence for these mutations detected in the control group.

RESULTS

Prevalences for factor V Leiden mutation (or=2.58; 95% confidence interval: 0.83-8.04), prothrombin 20210A mutation (or=2.03; 95% confidence interval: 0.51-8.01), were comparable between cases and controls (4.9% versus 1.9% and 2.9% versus 1.4%, respectively). Frequencies for these two polymorphisms significantly increased in subgroups of SGA infants with a normal Pourcelot index (13/133 versus 7/203; P=0.04), a gestational age > or =37 weeks of gestation (15/143 versus 7/203; P=0.01), a vaginal delivery (11/117 versus 7/203; P=0.04), a birth weight > or =2000 g (12/121 versus 7/203; P=0.03), no admission to paediatric ward (11/116 versus 7/203; P=0.01), a low Ponderal index <2.5(e) centile (6/45 versus 7/203; P=0.04), and normal head circumference >10th centile (7/53 versus 7/203; P=0.01) in comparison with the control group.

CONCLUSIONS

An association was found between polymorphisms for factor V Leiden and prothrombin, and asymmetrical intrauterine growth restriction with immediate favourable neonatal outcomes.

Inherited thrombophilia and gestational vascular complications

The most common causes of inherited thrombophilia, the factor V Leiden and the factor II A20210 mutations, confer a higher risk of venous thromboembolism. Moreover, several studies have suggested that they can have a role in the occurrence of gestational vascular complications in otherwise unexplained recurrent fetal losses, hypertensive disorders of pregnancy and fetal growth restriction. Observational and case-control studies addressing these issues are available in literature. However, longitudinal, perspective studies are lacking. Mild hyperhomocysteinaemia can be due partly to inherited susceptibility--as the homozygous carriership of the T677 variant in the gene encoding 5,10-methylenetetrahydrofolate reductase (MTHFR). Case-control studies have been carried out on a possible association between unexplained fetal losses and mild hyperhomocysteinaemia. Although case-control and perspective studies are available on hyperhomocysteinaemia and other gestational vascular complications the data are conflicting.Intervention studies have been carried out to prevent adverse obstetric outcomes in women with factor V Leiden or factor II A20210 mutations and previous adverse outcomes. Although these are not randomized controlled trials, all have found significantly better outcomes in treated pregnancies compared to those of untreated pregnancies in the same women.

Maternal thrombophilia and neonatal thrombosis

In neonates and infants, numerous clinical and environmental conditions lead to elevated thrombin generation and subsequent thrombus formation. Genetic prothrombotic defects (protein C, protein S and antithrombin deficiency, mutations of coagulation factor V and factor II, elevated lipoprotein (a)) have been established as risk factors of thromboembolic events in neonates and infants. The interpretation of the laboratory evaluation relies on age-dependent normal reference values. Because appropriate clinical trials are missing in these age groups, treatment recommendations are adapted from small-scale studies in neonates and infants and from guidelines relating to adult patient protocols. Secondary long-term anticoagulation should be administered on an individual basis.

The association between birth weight and plasma fibrinogen is abolished after the elimination of genetic influences

Low birth weight is associated with an increased risk of atherothrombosis, which may be related in part to the association between low birth weight and high plasma fibrinogen. The association between birth weight and fibrinogen may be explained by intrauterine, socio-economic or genetic factors. We examined birth weight and fibrinogen in 52 dizygotic and 56 adolescent monozygotic (genetically identical) twin pairs. The dizygotic but not the monozygotic twins with the lowest birth weight from each pair had a fibrinogen level that was higher compared with their co-twins with the highest birth weight [dizygotic twins: 2.62 +/- 0.46 g L(-1) vs. 2.50 +/- 0.41 g L(-1) (P = 0.04); monozygotic twins: 2.42 +/- 0.45 g L(-1) vs. 2.49 +/- 0.39 g L(-1) (P = 0.2)]. These findings suggest that the association between birth weight and plasma fibrinogen is abolished after the elimination of genetic influences and therefore that this association has genetic causes. Improvement of intrauterine nutrition may not lower fibrinogen levels in later life.

Thromboembolism in children

Acquired and inherited prothrombotic risk factors increase the risk of thrombosis in children. This review is based on "milestone" pediatric reports and new literature data (January 2001-February 2002) on the presence of acquired and inherited prothrombotic risk factors, imaging methods, and treatment modalities in pediatric thromboembolism. After confirming clinically suspected thromboembolism with suitable imaging methods, pediatric patients should be screened for common gene mutations (factor V G1691A, prothrombin G20210A and MTHFR C677T genotypes), rare genetic deficiencies (protein C, protein S, antithrombin, and plasminogen), and new candidates for genetic thrombophilia causing elevated levels of lipoprotein(a), and homocysteine, and probable genetic risk factors (elevations in fibrinogen, factor IX, and factor VIIIC, and decreases in factor XII). Data interpretation is based on age-dependent reference ranges or the identification of causative gene mutations/polymorphisms with respect to individual ethnic backgrounds. Pediatric treatment protocols for acute thromboembolism, including thrombolytic and anticoagulant therapy, are mainly adapted from adult patient protocols.