Genetic risk factors for placental abruption: a HuGE review and meta-analysis

Placental abruption at near-term and term gestations: pathophysiology, epidemiology, diagnosis, and management

Placental abruption is the premature separation of the placenta from its uterine attachment before the delivery of a fetus. The clinical manifestations of abruption typically include vaginal bleeding and abdominal pain with a wide variety of abnormal fetal heart rate patterns. Clinical challenges arise when pregnant people with this condition present with profound vaginal bleeding, necessitating urgent delivery, especially when there is a concern for maternal and fetal compromise and coagulopathy. Abruption occurs in 0.6% to 1.2% of all pregnancies, with nearly half of abruption occurring at term gestations. An exposition of abruption at near-term (defined as the late preterm period from 34 0/7 to 36 6/7 weeks of gestation) and term (defined as ≥37 weeks of gestation) provides unique insights into its direct effects, as risks associated with preterm birth do not impact outcomes. Here, we explore the pathophysiology, epidemiology, and diagnosis of abruption. We discuss the interaction of chronic processes (decidual and uteroplacental vasculopathy) and acute processes (shearing forces applied to the abdomen) that underlie the pathophysiology. Risk factors for abruption and strengths of association are summarized. Sonographic findings of abruption and fetal heart rate tracings are presented. In addition, we propose a management algorithm for acute abruption that incorporates blood loss, vital signs, and urine output, among other factors. Lastly, we discuss blood component therapy, viscoelastic point-of-care testing, disseminated intravascular coagulopathy, and management of abruption complicated by fetal death. The review seeks to provide comprehensive, clinically focused guidance during a gestational age range when neonatal outcomes can often be favorable if rapid and evidence-based care is optimized.

Epidemiology, Risk Factors, and Perinatal Outcomes of Placental Abruption-Detailed Annual Data and Clinical Perspectives from Polish Tertiary Center

Placental abruption (PA) is a separation of the placenta from the uterine wall occurring with the fetus still present in the uterine cavity. It contributes to numerous neonatal and maternal complications, increasing morbidity and mortality. We conducted a retrospective study at a tertiary perinatal care center, which included 2210 cases of labor that took place in 2015 with a PA occurrence of 0.7%. No maternal or fetal death during delivery was reported in this period. The identified PA risk factors were uterine malformations, pPROM, placenta previa spectrum, and oligohydramnios. The significant maternal PA complications identified were maternal anemia, uterine rupture, and HELLP syndrome. Preterm delivery occurred significantly more often in the PA group, and the number of weeks of pregnancy and the birth weight at delivery were both significantly lower in the PA group. PA is a relatively rare perinatal complication with very serious consequences, and it still lacks effective prophylaxis and treatment. Despite its rare occurrence, each center should develop a certain strategy for dealing with this pathology or predicting which patients are at risk. Much work is still needed to ensure the proper care of the mother and the baby in this life-threatening condition.

Expression of the Costimulatory Molecule B7-H4 in the Decidua and Placental Tissues in Patients with Placental Abruption

B7 homolog 4 protein (B7-H4), a member of the B7 family, is a immunomodulatory membrane protein. The aim of the study was to evaluate the expression of this protein in the decidua and placental tissues in case of placental abruption (PA) compared to cases of retained placental tissue (RPT) and controls. Tissue samples were obtained from 47 patients with PA, 60 patients with RPT, and 41 healthy controls. The samples were stained for B7-H4 expression, analyzed by an expert pathologist, and a semi-quantitative scale was applied. A statistical analysis revealed that the expression of B7-H4 was significantly higher in the decidua in PA samples compared to samples from patients with RPT (p-value < 0.001) and healthy controls (p-value < 0.001). The expression of B7-H4 in the placental chorionic villus was significantly higher in PA samples in relation to samples from healthy controls (p-value < 0.001) but not in relation to RPT samples (p-value = 0.0853). This finding suggests that B7-H4 might play an important role in mechanisms restoring reproductive tract homeostasis. Further research is necessary in regard to the role of B7-H4 in PA.

A Data-Driven Review of the Genetic Factors of Pregnancy Complications

Over the recent years, many advances have been made in the research of the genetic factors of pregnancy complications. In this work, we use publicly available data repositories, such as the National Human Genome Research Institute GWAS Catalog, HuGE Navigator, and the UK Biobank genetic and phenotypic dataset to gain insights into molecular pathways and individual genes behind a set of pregnancy-related traits, including the most studied ones—preeclampsia, gestational diabetes, preterm birth, and placental abruption. Using both HuGE and GWAS Catalog data, we confirm that immune system and, in particular, T-cell related pathways are one of the most important drivers of pregnancy-related traits. Pathway analysis of the data reveals that cell adhesion and matrisome-related genes are also commonly involved in pregnancy pathologies. We also find a large role of metabolic factors that affect not only gestational diabetes, but also the other traits. These shared metabolic genes include IGF2, PPARG, and NOS3. We further discover that the published genetic associations are poorly replicated in the independent UK Biobank cohort. Nevertheless, we find novel genome-wide associations with pregnancy-related traits for the FBLN7, STK32B, and ACTR3B genes, and replicate the effects of the KAZN and TLE1 genes, with the latter being the only gene identified across all data resources. Overall, our analysis highlights central molecular pathways for pregnancy-related traits, and suggests a need to use more accurate and sophisticated association analysis strategies to robustly identify genetic risk factors for pregnancy complications.

Abruptio placentae risk and genetic variations in mitochondrial biogenesis and oxidative phosphorylation: replication of a candidate gene association study

BACKGROUND

Abruptio placentae is a complex multifactorial disease that is associated with maternal and neonatal death and morbidity. Abruptio placentae's high recurrence rate, high prevalence of heritable thrombophilia among women with abruptio placentae, and aggregation of cases in families of women with the disease support the possibility of a genetic predisposition. Previous genome-wide and candidate gene association studies have identified single nucleotide polymorphisms in mitochondrial biogenesis and oxidative phosphorylation genes that potentially are associated with abruptio placentae risk. Perturbations in mitochondrial biogenesis and oxidative phosphorylation, which results in mitochondrial dysfunction, can lead to the impairment of differentiation and invasion of the trophoblast and to several obstetrics complications that include abruptio placentae.

OBJECTIVE

The purpose of this study was to determine whether the results of a candidate genetic association study that indicated a link between DNA variants (implicated in mitochondrial biogenesis and oxidative phosphorylation) and abruptio placentae could be replicated.

STUDY DESIGN

The study was conducted among participants (507 abruptio placentae cases and 1090 control subjects) of the Placental Abruption Genetic Epidemiology study. Weighted genetic risk scores were calculated with the use of abruptio placentae risk-increasing alleles of 11 single nucleotide polymorphisms in 9 mitochondrial biogenesis and oxidative phosphorylation genes (CAMK2B, NR1H3, PPARG, PRKCA, THRB, COX5A, NDUFA10, NDUFA12, and NDUFC2), which previously was reported in the Peruvian Abruptio Placentae Epidemiology study, a study with similar design and study population to the Placental Abruption Genetic Epidemiology study. Logistic regression models were fit to examine associations of weighted genetic risk scores (quartile 1, <25th percentile; quartile 2, 25-50th percentile; quartile 3, 50-70th percentile, and quartile 4, >75th percentile) with risk of abruptio placentae, adjusted for population admixture (the first 4 principal components), maternal age, infant sex, and preeclampsia. The weighted genetic risk score was also modeled as a continuous predictor. To assess potential effect modification, analyses were repeated among strata that were defined by preeclampsia status, maternal age (≥35 vs 18-34 years), and infant sex.

RESULTS

Abruptio placentae cases were more likely to have preeclampsia, shorter gestational age, and lower infant birthweight. Participants in quartile 2 (score, 12.6-13.8), quartile 3 (score, 13.9-15.0) and quartile 4 (score, ≥15.1) had a genetic risk score of 1.45-fold (95% confidence interval, 1.04-2.02; P=.03), a 1.42-fold (95% confidence interval, 1.02-1.98; P=.04), and a 1.75-fold (95% confidence interval, 1.27-2.42; P=7.0E-04) higher odds of abruptio placentae, respectively, compared with those in quartile 1 (score,<12.6; P-for trend=.0003). The risk of abruptio placentae was 1.12-fold (95% confidence interval, 1.05-1.19; P=3.0×1004) higher per 1-unit increase in the score. Among women with preeclampsia, those in quartile 4 had a 3.92-fold (95% confidence interval, 1.48-10.36; P=.01) higher odds of abruptio placentae compared with women in quartile 1. Among normotensive women, women in quartile 4 had a 1.57-fold (95% confidence interval, 1.11-2.21; P=.01) higher odds of abruptio placentae compared with those in quartile 1 (P-for interaction=.12). We did not observe differences in associations among strata defined by maternal age or infant sex.

CONCLUSION

In this study, we replicated previous findings and provide strong evidence for DNA variants that encode for genes that are involved in mitochondrial biogenesis and oxidative phosphorylation pathways, which confers risk for abruptio placentae. These results shed light on the mechanisms that implicate DNA variants that encode for proteins in mitochondrial function that are responsible for abruptio placentae risk. Therapeutic efforts to reduce risk of abruptio placentae can be enhanced by improved biologic understanding of maternal mitochondrial biogenesis/oxidative phosphorylation pathways and identification of women who would be at high risk for abruptio placentae.

Genetic variations and risk of placental abruption: A genome-wide association study and meta-analysis of genome-wide association studies

INTRODUCTION

Accumulating epidemiological evidence points to strong genetic susceptibility to placental abruption (PA). However, characterization of genes associated with PA remains incomplete. We conducted a genome-wide association study (GWAS) of PA and a meta-analysis of GWAS.

METHODS

Participants of the Placental Abruption Genetic Epidemiology (PAGE) study, a population based case-control study of PA conducted in Lima, Peru, were genotyped using the Illumina HumanCore-24 BeadChip platform. Genotypes were imputed using the 1000 genomes reference panel, and >4.9 million SNPs that passed quality control were analyzed. We performed a GWAS in PAGE participants (507 PA cases and 1090 controls) and a GWAS meta-analysis in 2512 participants (959 PA cases and 1553 controls) that included PAGE and the previously reported Peruvian Abruptio Placentae Epidemiology (PAPE) study. We fitted population stratification-adjusted logistic regression models and fixed-effects meta-analyses using inverse-variance weighting.

RESULTS

Independent loci (linkage-disequilibrium<0.80) suggestively associated with PA (P-value<5e-5) included rs4148646 and rs2074311 in ABCC8, rs7249210, rs7250184, rs7249100 and rs10401828 in ZNF28, rs11133659 in CTNND2, and rs2074314 and rs35271178 near KCNJ11 in the PAGE GWAS. Similarly, independent loci suggestively associated with PA in the GWAS meta-analysis included rs76258369 near IRX1, and rs7094759 and rs12264492 in ADAM12. Functional analyses of these genes showed trophoblast-like cell interaction, as well as networks involved in endocrine system disorders, cardiovascular diseases, and cellular function.

CONCLUSIONS

We identified several genetic loci and related functions that may play a role in PA risk. Understanding genetic factors underlying pathophysiological mechanisms of PA may facilitate prevention and early diagnostic efforts.

Circadian clock-related genetic risk scores and risk of placental abruption

INTRODUCTION

The circadian clock plays an important role in several aspects of female reproductive biology. Evidence linking circadian clock-related genes to pregnancy outcomes has been inconsistent. We sought to examine whether variations in single nucleotide polymorphisms (SNPs) of circadian clock genes are associated with PA risk.

METHODS

Maternal blood samples were collected from 470 PA case and 473 controls. Genotyping was performed using the Illumina Cardio-MetaboChip platform. We examined 119 SNPs in 13 candidate genes known to control circadian rhythms (e.g., CRY2, ARNTL, and RORA). Univariate and penalized logistic regression models were fit to estimate odds ratios (ORs); and the combined effect of multiple SNPs on PA risk was estimated using a weighted genetic risk score (wGRS).

RESULTS

A common SNP in the RORA gene (rs2899663) was associated with a 21% reduced odds of PA (P < 0.05). The odds of PA increased with increasing wGRS (Ptrend < 0.001). The corresponding ORs were 1.00, 1.83, 2.81 and 5.13 across wGRS quartiles. Participants in the highest wGRS quartile had a 5.13-fold (95% confidence interval: 3.21-8.21) higher odds of PA compared to those in the lowest quartile. Although the test for interaction was not significant, the odds of PA was substantially elevated for preeclamptics with the highest wGRS quartile (OR = 14.44, 95%CI: 6.62-31.53) compared to normotensive women in the lowest wGRS quartile.

DISCUSSION

Genetic variants in circadian rhythm genes may be associated with PA risk. Larger studies are needed to corroborate these findings and to further elucidate the pathogenesis of this important obstetrical complication.

Change in paternity, risk of placental abruption and confounding by birth interval: a population-based prospective cohort study in Norway, 1967-2009

OBJECTIVES

We examined abruption risk in relation to change in paternity, and evaluated if birth interval confounds this association.

SETTING

Population-based study of singleton births in Norway between 1967 and 2009.

PARTICIPANTS

Women who had their first two (n=747 566) singleton births in the Norwegian Medical Birth Registry. The associations between partner change between pregnancies and birth interval were examined in relation to abruption in a series of logistic regression models.

PRIMARY OUTCOME MEASURES

Risk, as well as unadjusted and adjusted OR of placental abruption in relation to change in paternity and interval between births.

RESULTS

Among women without abruption in their first pregnancy, the risks of abruption in the second pregnancy were 4.7 and 6.5 per 1000 in women who had the same and different partners, respectively (OR=1.39, 95% CI 1.26 to 1.53). After adjustments for confounders including birth interval and smoking, partner change was not associated with abruption (OR=1.01, 95% CI 0.79 to 1.32). Among women with abruption in the first pregnancy, the association between partner change and abruption in the second pregnancy was 0.98 (95% CI 0.75 to 1.28). Interval <1 year was associated with increased abruption risk in the second pregnancy among women with the same as well as different partners, but interval over 4 years was only associated with increased risk among women with the same partner. No such patterns were seen for recurrent abruption.

CONCLUSIONS

We find no evidence that a change in partner is associated with increased abruption risk. Theories supporting an immune maladaptation hypothesis afforded by change in paternity are not supported insofar as abruption is concerned.

A systematic appraisal of field synopses in genetic epidemiology: a HuGE review

Evidence from genetic association studies is accumulating rapidly. Field synopses have recently arisen as an unbiased way of systematically synthesizing this evidence. We performed a systematic review and appraisal of published field synopses in genetic epidemiology and assessed their main findings and methodological characteristics. We identified 61 eligible field synopses, published between January 1, 2007, and October 31, 2013, on 52 outcomes reporting 734 significant associations at the P < 0.05 level. The median odds ratio for these associations was 1.25 (interquartile range, 1.15-1.43). Egger's test was the most common method (n = 30 synopses) of assessing publication bias. Only 12 synopses (20%) used the Venice criteria to evaluate the epidemiologic credibility of their findings (n = 449 variants). Eleven synopses (18%) were accompanied by an online database that has been regularly updated. These synopses received more citations (P = 0.01) and needed a larger research team (P = 0.02) than synopses without an online database. Overall, field synopses are becoming a valuable tool for the identification of common genetic variants, especially when researchers follow relevant methodological guidelines. Our work provides a summary of the current status of the field synopses published to date and may help interested readers efficiently identify the online resources containing the relevant genetic evidence.

Placental genome and maternal-placental genetic interactions: a genome-wide and candidate gene association study of placental abruption

While available evidence supports the role of genetics in the pathogenesis of placental abruption (PA), PA-related placental genome variations and maternal-placental genetic interactions have not been investigated. Maternal blood and placental samples collected from participants in the Peruvian Abruptio Placentae Epidemiology study were genotyped using Illumina's Cardio-Metabochip platform. We examined 118,782 genome-wide SNPs and 333 SNPs in 32 candidate genes from mitochondrial biogenesis and oxidative phosphorylation pathways in placental DNA from 280 PA cases and 244 controls. We assessed maternal-placental interactions in the candidate gene SNPS and two imprinted regions (IGF2/H19 and C19MC). Univariate and penalized logistic regression models were fit to estimate odds ratios. We examined the combined effect of multiple SNPs on PA risk using weighted genetic risk scores (WGRS) with repeated ten-fold cross-validations. A multinomial model was used to investigate maternal-placental genetic interactions. In placental genome-wide and candidate gene analyses, no SNP was significant after false discovery rate correction. The top genome-wide association study (GWAS) hits were rs544201, rs1484464 (CTNNA2), rs4149570 (TNFRSF1A) and rs13055470 (ZNRF3) (p-values: 1.11e-05 to 3.54e-05). The top 200 SNPs of the GWAS overrepresented genes involved in cell cycle, growth and proliferation. The top candidate gene hits were rs16949118 (COX10) and rs7609948 (THRB) (p-values: 6.00e-03 and 8.19e-03). Participants in the highest quartile of WGRS based on cross-validations using SNPs selected from the GWAS and candidate gene analyses had a 8.40-fold (95% CI: 5.8-12.56) and a 4.46-fold (95% CI: 2.94-6.72) higher odds of PA compared to participants in the lowest quartile. We found maternal-placental genetic interactions on PA risk for two SNPs in PPARG (chr3:12313450 and chr3:12412978) and maternal imprinting effects for multiple SNPs in the C19MC and IGF2/H19 regions. Variations in the placental genome and interactions between maternal-placental genetic variations may contribute to PA risk. Larger studies may help advance our understanding of PA pathogenesis.

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.

Abruptio placentae in cynomolgus macaques (Macaca fascicularis): male bias

BACKGROUND

Abruptio placentae is a serious problem with a high rate of maternal and fetal mortality and documented sexual dimorphism in reoccurrence. Macaca fascicularis is a well-described reproductive model; however, there are no data available regarding sexual dimorphism in abruptio placentae in these species.

METHODS

A retrospective study of pathology and medical records in a large colony of M. fascicularis was performed. Placental specimens were analyzed.

RESULTS

The incidence of placenta abruptio in the colony was 15.7/1000 births. In the abruptio placentae group, male fetuses had lower placental disk length and increased femur length compared with female fetuses. The feto-pacental ratio and fetal weight were lower in the male fetuses in the abruption group compared with those in the stillbirth group without abruption placentae.

CONCLUSION

This is the first documentation of male bias in placental and fetal development in abruptio placentae in non-human primates.

Thrombophilias and adverse pregnancy outcomes: results from the Danish National Birth Cohort

BACKGROUND

Inherited thrombophilias have inconsistently been linked to adverse pregnancy outcomes. Differences in study design, size and population could explain this heterogeneity.

OBJECTIVE

The aim of the present study was to evaluate if factor (F)V Leiden G1691A, prothrombin mutation G20210A (PTM) and methylenetetrahydrofolate reductase C677T (MTHFR) increased the risk of severe preeclampsia, fetal growth restriction, very preterm delivery, placental abruption and a composite of these outcomes also including stillbirth.

PATIENTS AND METHODS

In a nested case-cohort study of pregnant women in Denmark, we genotyped 2032 cases and 1851 random controls. Each of the medical records of the cases was validated. We calculated both genomic and allelic models, and present both models. We also performed sensitivity analyses adjusting for parity, age, smoking, body mass index and socioeconomic status.

RESULTS

In the allelic models, FV Leiden increased the risk of the composite outcome (odds ratio [OR] 1.4, 95% confidence interval [CI] 1.1-1.8), severe preeclampsia (OR 1.6, 95% CI 1.1-2.4), fetal growth restriction (OR 1.4, 95% CI 1.1-1.8) and placental abruption (OR = 1.7 (95% CI 1.2-2.4). In the sensitivity analyses, adjustment diminished these estimates slightly. PTM was not significantly associated with any of the outcomes, and MTHFR was only significantly associated with severe preeclampsia (OR 1.3, 95% CI 1.1-1.6).

CONCLUSION

FV Leiden predisposes to adverse pregnancy outcomes in a setting of Scandinavian women.

Rare case of spina bifida in both twins with possible genetic basis

Neural tube defects (NTD) are a group of congenital malformations of the brain and spine, the etiology of which is still debated. Although presumed to be the consequence of interactions between genetic and environmental factors, so far, it is not known which genes are involved in the pathogenesis of these malformations. NTD affecting both fetuses in a twin gestation is a rare event. In view of this rarity, we present a case of dichorionic diamniotic twin pregnancy with spina bifida in both fetuses concordantly. This gestation was preceeded by another dichorionic diamniotic twin pregnancy that was complicated by placental abruption.

Risk of placental abruption in relation to maternal depressive, anxiety and stress symptoms

BACKGROUND

Little is known about the influence of psychiatric factors on the etiology of placental abruption (PA), an obstetrical condition that complicates 1-2% of pregnancies. We examined the risk of PA in relation to maternal psychiatric symptoms during pregnancy.

METHODS

This case-control study included 373 PA cases and 368 controls delivered at five medical centers in Lima, Peru. Depressive, anxiety and stress symptoms were assessed using the Patient Health Questionnaire (PHQ-9) and the Depression Anxiety Stress Scales (DASS-21). Multivariable logistic regression models were fit to calculate odds ratios (aOR) and 95% confidence intervals (CI) adjusted for confounders.

RESULTS

Depressive symptoms of increasing severity (using the DASS depression subscale) was associated with PA (p for trend=0.02). Compared with women with no depressive symptoms, the aOR (95%CI) for PA associated with each level of severity of depression symptoms based on the DASS assessment were as follows: mild 1.84 (0.91-3.74); moderate 1.25 (0.67-2.33); and severe 4.68 (0.98-22.4). The corresponding ORs for mild, moderate, and moderately severe depressive symptoms based on the PHQ assessment were 1.10 (0.79-1.54), 3.31 (1.45-7.57), and 5.01 (1.06-23.6), respectively. A positive gradient was observed for the odds of PA with severity of anxiety (p for trend=0.002) and stress symptoms (p for trend=0.002).

LIMITATIONS

These cross-sectionally collected data may be subject to recall bias.

CONCLUSIONS

Maternal psychiatric disorders may be associated with an increased occurrence of AP. Larger studies that allow for more precise evaluations of maternal psychiatric health in relation to PA risk are warranted.

Novel insights into molecular mechanisms of abruption-induced preterm birth

Preterm birth (PTB) complicates more than 12% of all deliveries. Despite significant research, the aetiology of most cases of PTB remains elusive. Two major antecedents of PTB, intra-amniotic infection and decidual haemorrhage (abruption), can exhibit dissimilar demographic and genetic predispositions, despite sharing common molecular and cellular pathways. The use of high-throughput, high-dimensional technologies reveals substantial crosstalk between the coagulation and inflammation pathways. Tissue factor, thrombin and cytokines are key mediators of this crosstalk. Abruptions are associated with excess thrombin generated from decidual-cell-expressed tissue factor. Although thrombin is a primary mediator of the coagulation cascade, it can also promote inflammation-associated PTB by enhancing expression of matrix metalloproteinase and neutrophil-chemoattracting and -activating chemokines. Here, we provide novel insights into the molecular mechanisms and pathways leading to PTB in the setting of placental abruption.

Risk of placental abruption in relation to migraines and headaches

Background

Migraine, a common chronic-intermittent disorder of idiopathic origin characterized by severe debilitating headaches and autonomic nervous system dysfunction, and placental abruption, the premature separation of the placenta, share many common pathophysiological characteristics. Moreover, endothelial dysfunction, platelet activation, hypercoagulation, and inflammation are common to both disorders. We assessed risk of placental abruption in relation to maternal history of migraine before and during pregnancy in Peruvian women.

Methods

Cases were 375 women with pregnancies complicated by placental abruption, and controls were 368 women without an abruption. During in-person interviews conducted following delivery, women were asked if they had physician-diagnosed migraine, and they were asked questions that allowed headaches and migraine to be classified according to criteria established by the International Headache Society. Logistic regression procedures were used to calculate odds ratios (aOR) and 95% confidence intervals (CI) adjusted for confounders.

Results

Overall, a lifetime history of any headaches or migraine was associated with an increased odds of placental abruption (aOR = 1.60; 95% CI 1.16-2.20). A lifetime history of migraine was associated with a 2.14-fold increased odds of placental abruption (aOR = 2.14; 95% CI 1.22-3.75). The odds of placental abruption was 2.11 (95% CI 1.00-4.45) for migraineurs without aura; and 1.59 (95% 0.70-3.62) for migraineurs with aura. A lifetime history of tension-type headache was also increased with placental abruption (aOR = 1.61; 95% CI 1.01-2.57).

Conclusions

This study adds placental abruption to a growing list of pregnancy complications associated with maternal headache/migraine disorders. Nevertheless, prospective cohort studies are needed to more rigorously evaluate the extent to which migraines and/or its treatments are associated with the occurrence of placental abruption.

The Normal anticoagulant system and risk of placental abruption: protein C, protein S and resistance to activated protein C

OBJECTIVE

To examine the association between maternal thrombophilia associated with anticoagulation (proteins C and S and activated protein C resistance ratio, APCR) and risk of placental abruption.

METHODS

Data were derived from a case-control study - The New Jersey-Placental Abruption Study (2002-2007). Maternal blood was collected from abruption cases and controls and was assayed for the thrombophilias. Decreased protein C, S and APCR was defined as values <5% and <10% among controls.

RESULTS

Of a total of 132 cases and 127 controls, 3 were heterozygous for the factor V Leiden mutation (1 case and 2 controls). Mean (± standard deviation) protein C (114.2 ± 25.6 vs. 121.4 ± 27.6; P=0.009), protein S (39.9 ± 18.4 vs. 35.7 ± 15.2; P=0.043) and APCR (2.86 ± 0.29 vs. 2.88 ± 0.27; P=0.039) were different between cases and controls. Abruption cases were associated with an odds ratio of 3.2 (95% CI 1.2, 9.9) in relation to decreased protein C (<Fifth centile). Decreases in both protein S and APCR ratio were not associated with abruption.

CONCLUSIONS

A decrease in protein C was associated with an increased risk for abruption, suggesting an important role for the physiologic anticoagulant system in the etiology of placental abruption.

Genetic variants of homocysteine/folate metabolism pathway and risk of inflammatory bowel disease: a synopsis and meta-analysis of genetic association studies

A synopsis and meta-analysis of studies that investigated the association between genetic variants involved in the homocysteine/folate metabolism pathway and risk of inflammatory bowel disease (IBD) were conducted. Four variants (MTHFR C6TTT, MTHFR A1298C, MTR A2756G and MTRR A66G) showed significant associations in individual studies. In meta-analyses, only the variant MTR A2756G indicated an association with the risk of IBD for the allele contrast and the dominant model (odds ratio (OR) 1.48 (1.12-1.97) and OR 1.55 (1.12-2.15), respectively). The effect sizes for Crohn's disease and ulcerative colitis were similar to IBD. Cumulative meta-analysis for C677T indicated a downward trend of association as information accumulates.

Glutathione S-transferase M1 and T1 genes and susceptibility to chronic myeloid leukemia: a meta-analysis

Variants of glutathione S-transferase M1 (GSTM1) and T1 (GSTT1) genes have been implicated as risk factors for chronic myeloid leukemia (CML). However, the genetic association studies that examined the relation between the null genotypes of GSTM1 and GSTT1 genes and risk of developing CML gave conflicting or inconclusive results. In an attempt to interpret these results, a meta-analysis of all available studies (nine studies, with 757 cases and 1959 controls) was performed. In the meta-analysis the pooled odds ratios (OR) were estimated using random effects models. The heterogeneity between studies, the sources of potential bias, and the consistency of genetic effects across ethnicities were explored. Cumulative meta-analysis was also performed. Overall, the meta-analysis showed nonsignificant association between GSTM1 null genotype and CML (OR = 1.00 [0.83-1.20]) and lack of heterogeneity between the studies (p(Q) = 0.87). The association was also nonsignificant in Whites, East Asians, and Indians: OR = 1.38 (0.43-4.46), 0.94 (0.65-1.35), and 1.16 (0.74-1.82), respectively. However, GSTT1 null genotype was associated with increased risk of CML (OR = 1.57 [1.13-2.17]) and the heterogeneity between studies was significant (p(Q) = 0.04). In Indians, the association was significant (OR = 2.89 [1.56-5.35]) whereas in East Asians it was not significant (OR = 1.07 [0.74-1.54]). The combined GSTM1 normal/GSTT1 null genotypes produced significant association (OR = 1.95 [1.17-3.24]). Cumulative meta-analysis for GSTT1 gene showed an upward trend in risk effect, whereas the trend was downward in GSTM1. There was a differential magnitude of effect in large versus small studies. In conclusion, the accumulated evidence indicated an association between GSTT1 null genotype and CML.

Polymorphisms in thrombophilia and renin-angiotensin system pathways, preterm delivery, and evidence of placental hemorrhage

OBJECTIVE

The purpose of this study was to analyze functional polymorphisms in candidate genes (methylenetetrahydrofolate reductase [MTHFR]677C>T, MTHFR1298A>C, factor 5 1691G>A [FVL], and angiotensinogen (AGT)-6G>A) in relation to a hypothesized placental hemorrhage pathway to preterm delivery (PTD).

STUDY DESIGN

We assessed maternal genotypes, pregnancy outcomes, and placental pathologic evidence among 560 white and 399 black women who were recruited at mid trimester into a prospective cohort study (1998-2004). Odds of dominant genotypes were calculated for PTDs with (n = 56) or without (n = 177) evidence of placental hemorrhage (referent = term) with the use of race-stratified polytomous logistic regression models.

RESULTS

Among white women, FVL GA/AA and AGT(-6) GA/AA were both associated with hemorrhage-related PTDs (odds ratio [OR], 4.8; 95% confidence interval [CI], 1.6-14.2 and OR, 3.8; 95% CI, 1.3-10.5, respectively), but not other PTDs (ORs, 1.2 and 0.9, respectively). FVL GA/AA was associated with placental abruption (OR, 5.8; 95% CI, 1.1-30) among white women. All results were null for MTHFR genotypes.

CONCLUSION

FVL and AGT variant genotypes were associated specifically with hemorrhage-related PTDs.

A field synopsis and meta-analysis of genetic association studies in peripheral arterial disease: The CUMAGAS-PAD database

In an electronic search of the literature, the authors systematically retrieved all published studies that investigated genetic susceptibility to peripheral arterial disease (PAD). They created a comprehensive database of all eligible studies, collecting detailed genetic and bioinformatics data on each polymorphism. Data from eligible studies were synthesized using meta-analysis techniques. Gene variants were classified into distinct pathophysiologic pathways, and their potential involvement in PAD pathogenesis was determined. Forty-one publications that examined 44 gene polymorphisms were included. For 37 polymorphisms, the variant form had a functional effect. Twenty-three polymorphisms in 22 potential PAD candidate genes (F2, FGB, MTHFR, ITGB3, ACE, AGT, IL6, CCL2, ICAM1, SELE, MMP9, PPARG, MMP1, ADD1, P2RY12, LIPC, PLA2G7, SCARB1, MMP3, MTTP, LPA, CHRNA3) showed a significant association in individual studies. Eighty-eight percent of the studies had statistical power of less than 50%, and in 15 studies the genotype distribution in the control group did not conform to Hardy-Weinberg equilibrium. Data on 12 polymorphisms (F5 1691 G/A, MTHFR 677C/T, F2 20210 G/A, ITGB3 1565 T/C, ACE I/D, AGT 704C/T, AGT -6G/A, AGT 733C/T, IL6 -174 G/C, MMP9 -1562C/T, ICAM1 1462A/G, CHRNA3 831C/T) were synthesized, and a positive association was found for 3 (IL6 -174 G/C, ICAM1 1462A/G, CHRNA3 831C/T).

Variants of the arachidonate 5-lipoxygenase-activating protein (ALOX5AP) gene and risk of stroke: a HuGE gene-disease association review and meta-analysis

Variants of the arachidonate 5-lipoxygenase-activating protein (ALOX5AP) gene have been implicated as a risk factor for stroke. However, genetic association studies that have examined the association between ALOX5AP gene variants (HapA haplotype, HapB haplotype, and SG polymorphisms) and stroke have produced conflicting results. Therefore, the authors performed a meta-analysis of all studies with ALOX5AP genotyping (5,194 stroke cases and 4,566 controls). The meta-analysis showed significant heterogeneity among studies (P(Q) = 0.03, I(2) = 63%) and a nonsignificant association between the HapA haplotype (SG13S25G-SG13S114T-SG13S89G-SG13S32A) and stroke risk (random-effects (RE) odds ratio (OR) = 1.13, 95% confidence interval (CI): 0.88, 1.45). Regarding the HapB haplotype (SG13S377A-SG13S114A-SG13S41A-SG13S35G), there was no association with stroke risk (RE OR = 1.03, 95% CI: 0.77, 1.37). The SG13S114, SG13S89, SG13S25, SG13S32, SG13S35, and SG13S42 polymorphisms were not associated with stroke. The SG13S106 and SG13S377 polymorphisms revealed evidence of marginal association (RE OR = 1.23 (95% CI: 1.03, 1.46) and RE OR = 1.25 (95% CI: 1.04, 1.50), respectively). However, cumulative meta-analysis for the HapA haplotype showed a downward trend of odds ratios over time, and recursive cumulative meta-analysis indicated insufficient evidence for claiming or denying an association. Tests for bias revealed no evidence of biases. Rigorous genetic association studies investigating gene-gene-environment interactions may generate more conclusive claims about the genetics of stroke.

Occurrence of placental abruption in relatives

OBJECTIVE

The aim of this study was to assess the recurrence of placental abruption by severity, comparing the risk in a woman with that of recurrence in her sister and in the partner of her brother.

DESIGN

Prospective observational study.

SETTING

General population.

POPULATION

Population-based study based on records of pregnancies from the Medical Birth Registry of Norway; 377.902 sisters with 767 395 pregnancies, 168,142 families incorporating 2-10 sisters, and 346,385 brothers with 717,604 pregnancies in their partners were identified.

METHODS

Placental abruption with preterm birth, birthweight below 2500 g or perinatal death was defined as severe, other cases as mild. Because of the nested family data structure, multilevel multivariate regression was used.

MAIN OUTCOME MEASURES

Placental abruption (severe and mild).

RESULTS

Adjusted odds ratios of recurrence of mild and severe abruption were 6.5 (1.7%) and 11.5 (3.8%), respectively, compared with risks of 0.2 and 0.3% in the total population. After a severe abruption, odds ratios in her sisters were 1.7-2.1, whereas mild abruption produced no increased recurrence in sisters. The estimated heritability between sisters of severe abruption was 16%. No excess rate of abruption was observed between sisters and brothers' partners, between brothers' partners, or from brothers' partners to sisters. The odds ratios for a third abruption after a second abruption and a second severe abruption were 38.7 (19%) and 50.1 (24%), respectively.

CONCLUSIONS

The recurrence risk of placental abruption in the same woman was higher after severe than mild abruption. Severe abruption was associated with a two-fold risk in sisters. Pregnancies following a second abruption should be considered very high risk.