Molecular epidemiology of preeclampsia

Regulators involved in trophoblast syncytialization in the placenta of intrauterine growth restriction

Placental dysfunction refers to the insufficiency of placental perfusion and chronic hypoxia during early pregnancy, which impairs placental function and causes inadequate supply of oxygen and nutrients to the fetus, affecting fetal development and health. Fetal intrauterine growth restriction, one of the most common outcomes of pregnancy-induced hypertensions, can be caused by placental dysfunction, resulting from deficient trophoblast syncytialization, inadequate trophoblast invasion and impaired vascular remodeling. During placental development, cytotrophoblasts fuse to form a multinucleated syncytia barrier, which supplies oxygen and nutrients to meet the metabolic demands for fetal growth. A reduction in the cell fusion index and the number of nuclei in the syncytiotrophoblast are found in the placentas of pregnancies complicated by IUGR, suggesting that the occurrence of IUGR may be related to inadequate trophoblast syncytialization. During the multiple processes of trophoblasts syncytialization, specific proteins and several signaling pathways are involved in coordinating these events and regulating placental function. In addition, epigenetic modifications, cell metabolism, senescence, and autophagy are also involved. Study findings have indicated several abnormally expressed syncytialization-related proteins and signaling pathways in the placentas of pregnancies complicated by IUGR, suggesting that these elements may play a crucial role in the occurrence of IUGR. In this review, we discuss the regulators of trophoblast syncytialization and their abnormal expression in the placentas of pregnancies complicated by IUGR.

Preeclampsia, Natural History, Genes, and miRNAs Associated with the Syndrome

Preeclampsia (PE) is a hypertensive disease that affects pregnant women after 20 weeks of gestation. This disease is associated with an important risk of maternal and fetal mortality. PE is described as a placental pathology because, after delivery, most women recover normal arterial pressure. Poor invasion of the spiral arteries is a phenomenon well described in PE; this leads to a hypoxic uterine bed and imbalance of antiangiogenic and proangiogenic factors in the uteroplacental region, which in turn triggers the disease phenotype. The causes of the pathology are unclear; nevertheless, numerous approaches, including next-generation sequencing, association, and case control and miRNA studies, have shed light on the genetic/molecular basis of PE. These studies help us better understand the disease to advance new treatment strategies.

Is Supplementation with Micronutrients Still Necessary during Pregnancy? A Review

INTRODUCTION

Proper nutrition during pregnancy is important to prevent nutritional imbalances that interfere with pregnancy. Micronutrients play critical roles in embryogenesis, fetal growth, and maternal health, as energy, protein, vitamin, and mineral needs can increase during pregnancy. Increased needs can be met by increasing the intake of dietary micronutrients. Severe micronutrient deficiency or excess during pregnancy can have negative effects on fetal growth (intrauterine growth retardation, low birth weight, or congenital malformations) and pregnancy development (pre-eclampsia or gestational diabetes). We investigate whether it is necessary to continue micronutrient supplementation during pregnancy to improve women's health in this stage and whether this supplementation could prevent and control pathologies associated with pregnancy.

AIM

The present review aims to summarize evidence on the effects of nutritional deficiencies on maternal and newborn morbidity.

METHODS

This aim is addressed by critically reviewing results from published studies on supplementation with different nutrients during pregnancy. For this, major scientific databases, scientific texts, and official webpages have been consulted. PubMed searches using the terms "pregnancy" OR "maternal-fetal health" AND "vitamins" OR "minerals" OR "supplementation" AND "requirement" OR "deficiency nutrients" were performed.

RESULTS

There are accepted interventions during pregnancy, such as folic acid supplementation to prevent congenital neural tube defects, potassium iodide supplementation to correct neurodevelopment, and oral iron supplementation during the second half of pregnancy to reduce the risk of maternal anemia and iron deficiency. A number of micronutrients have also been associated with pre-eclampsia, gestational diabetes mellitus, and nausea and vomiting in pregnancy. In general, experimental studies are necessary to demonstrate the benefits of supplementation with different micronutrients and to adjust the recommended daily doses and the recommended periconceptional nutrition for mothers.

CONCLUSIONS

Presently, there is evidence of the benefits of micronutrient supplementation in perinatal results, but indiscriminate use is discouraged due to the fact that the side effects of excessive doses are not known. Evidence supports the idea that micronutrient deficiencies negatively affect maternal health and the outcome of pregnancy. No single micronutrient is responsible for the adverse effects; thus, supplementing or correcting one deficiency will not be very effective while other deficiencies exist.

Chorionic villus sampling and preeclampsia & eclampsia: coincidence or not?

OBJECTIVES

The purpose of the study is to investigate potential association of chorionic villus sampling (CVS) with subsequent development of preeclampsia (PE) and eclampsia (E).

STUDY DESIGN

The development of PE and E was compared between two groups as follows: 1- CVS group: women who underwent CVS (n = 228) and 2- Control group: maternal and gestational age matched women without invasive prenatal diagnostic procedure (n = 456). Main outcome measures were incidence of PE (mild, severe) and E.

RESULTS

The incidence of PE and E was not significantly different between CVS and control groups. There was no significant difference regarding mild and severe PE development between the two groups. The incidence of early- and late-onset PE was similar in CVS and control groups.

CONCLUSIONS

CVS does not appear to increase the risk of PE and E. The spontaneous elevation of trophoblastic load in the maternal circulation rather than the iatrogenic elevation through CVS may contribute to the development of PE and E.

MZe786, a hydrogen sulfide-releasing aspirin prevents preeclampsia in heme oxygenase-1 haplodeficient pregnancy under high soluble flt-1 environment

Preeclampsia affects one in twelve of the 130 million pregnancies a year. The lack of an effective therapeutic to prevent or treat it is responsible for an annual global cost burden of 100 billion US dollars. Preeclampsia also affects these women later in life as it is a recognised risk factor for cardiovascular disease, stroke and vascular dementia. Our laboratory demonstrated that preeclampsia is associated with high soluble fms-like tyrosine kinase 1 (sFlt-1) and low heme oxygenase-1 (HO1/Hmox1) expression. Here we sought to determine the therapeutic value of a novel H₂S-releasing aspirin (MZe786) in HO-1 haploid deficient (Hmox1^+/−) pregnant mice in a high sFlt-1 environment. Pregnant Hmox1^+/− mice were injected with adenovirus encoding sFlt-1 or control virus at gestation day E11.5. Subsequently, Hmox1^+/− dams were treated daily with a number of treatment regimens until E17.5, when maternal and fetal outcomes were assessed. Here we show that HO-1 compromised mice in a high sFlt-1 environment during pregnancy exhibit severe preeclampsia signs and a reduction in antioxidant genes. MZe786 ameliorates preeclampsia by reducing hypertension and renal damage possibly by stimulating antioxidant genes. MZe786 also improved fetal outcome in comparison with aspirin alone and appears to be a better therapeutic agent at preventing preeclampsia than aspirin alone.

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Partial loss of heme oxygenase-1 under high soluble Flt-1 causes severe preeclampsia compared to high sFlt-1 alone.

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MZe786, hydrogen sulfide releasing aspirin prevents preeclampsia by suppressing maternal hypertension and kidney injury.

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MZe786 is able to rescue pregnancy and improves fetal outcome despite the persistent high levels of sFlt-1.

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MZe786 is a superior therapeutic candidate than aspirin in preventing preeclampsia.

MZe786 Rescues Cardiac Mitochondrial Activity in High sFlt-1 and Low HO-1 Environment

Hypertensive disorder in pregnancy is a major cause of maternal and perinatal mortality worldwide. Women who have had preeclampsia are at three to four times higher risk in later life of developing high blood pressure and heart disease. Soluble Flt-1 (sFlt-1) is elevated in preeclampsia and may remain high postpartum in women with a history of preeclampsia. Heme oxygenase-1 (Hmox1/HO-1) exerts protective effects against oxidative stimuli and is compromised in the placenta of pregnant women with preeclampsia. We hypothesized that sFlt-1 inhibits cardiac mitochondrial activity in HO-1 deficient mice. HO-1 haplo-insufficient mice (Hmox1^+/−) were injected with adenovirus encoding sFlt-1 (Ad-sFlt-1) or control virus (Ad-CMV). Subsequently, they were treated daily with either placebo or MZe786 for six days, when the heart tissue was harvested to assess cardiac mitochondrial activity. Here, we show that the loss of HO-1 disturbed cardiac mitochondrial respiration and reduced mitochondrial biogenesis. The overexpression of sFlt-1 resulted in the inhibition of the cardiac mitochondrial activity in Hmox1^+/− mice. The present study demonstrates that the hydrogen sulfide (H₂S) releasing molecule, MZe786, rescues mitochondrial activity by stimulating cardiac mitochondrial biogenesis and antioxidant defense in Hmox1^−/− mice and in Hmox1^+/− mice exposed to a high sFlt-1 environment.

PHLDA2 gene polymorphisms and risk of HELLP syndrome and severe preeclampsia

OBJECTIVE

Pleckstrin homology-like domain, family A, member 2 (PHLDA2) is a maternally expressed imprinted gene. Loss of imprinting in PHLDA2 is associated with abnormal placental development and fetal growth restriction. Our objective was to determine whether genetic variation in PHLDA2 is also associated with risk of HELLP syndrome and preeclampsia (PE) with severe features.

STUDY DESIGN

Case (n = 162) and control (n = 33) mother-father-child triads were recruited using an internet-based method. Medical records were reviewed to verify clinical diagnosis of self-reported cases. DNA was genotyped for three polymorphisms in the PHLDA2 gene using TaqMan assays: rs13390, rs1056819, rs2583435.

MAIN OUTCOME MEASURES

To examine the association between minor alleles and haplotypes with HELLP syndrome and PE with severe features, relative risks and 95% confidence intervals were estimated using log-linear models, adjusting for the correlation between familial genotypes, using HAPLIN.

RESULTS

There was no association identified between PHLDA2 gene polymorphisms or haplotypes and HELLP syndrome and PE with severe features. No parent-of-origin effects were observed.

CONCLUSION

Genetic variation in the PHLDA2 gene is not associated with HELLP syndrome or PE with severe features.

Investigation of Maternal Effects, Maternal-Fetal Interactions, and Parent-of-Origin Effects (Imprinting) for Candidate Genes Positioned on Chromosome 18q21, in Probands with Schizophrenia and their First-Degree Relatives

OBJECTIVE

A popular design for the investigation of such effects, including effects of parent-of-origin (imprinting), maternal genotype, and maternal-fetal genotype interactions, is to collect deoxyribonucleic acid (DNA) from affected offspring and their mothers and to compare with an appropriate control sample. We investigate the effects of estimation of maternal, imprinting and interaction effects using multimodal modeling using parents and their offspring with schizophrenia in Korean population.

METHODS

We have recruited 27 probands (with schizophrenia) with their parents and siblings whenever possible. We analyzed 20 SNPs of 7 neuronal genes in chromosome 18. We used EMIM analysis program for the estimation of maternal, imprinting and interaction effects using multimodal modeling.

RESULTS

Of analyzed 20 single nucleotide polymorphisms (SNPs), significant SNP (rs 2276186) was suggested in EMIM analysis for child genetics effects (p=0.0225438044) and child genetic effects allowing for maternal genetic effects (p=0.0209453210) with very stringent multiple comparison Bonferroni correction.

CONCLUSION

Our results are the pilot study for epigenetic study in mental disorder and help to understanding and use of EMIM statistical genetics analysis program with many limitations including small pedigree numbers.

Longitudinal Study of Delta-Aminolevulinate Dehydratase Activity and Oxidative Profile in Healthy Pregnant Women

Pregnancy is characterized by changes in various organs, triggering changes in the use of energy substrates and increased oxygen consumption. In addition, gestation is an oxidative event that can be assessed by the relationship between free radicals and antioxidants produced by the body. Excessive production of free radicals has detrimental effects such as damage to enzymes, carbohydrates, and DNA. Thus, the objective of this study was to evaluate the oxidative status and antioxidant responses throughout pregnancy through a longitudinal study. Reactive oxygen species were analyzed by means of thiobarbituric acid reactive substances and nitric oxide, the antioxidant system through vitamin C, sulfhydryl groups, total antioxidant capacity, and ferric reducing ability of plasma as well as enzymes such as catalase and delta-aminolevulinate-dehydratase in pregnant women in the three gestational trimesters (n = 30). According to the results, the markers of oxidative damage showed significant differences in the different gestational trimesters where they were increased in the second trimester when compared to the first trimester. The antioxidant defenses responded differently in each gestational trimester, suggesting a response pattern to try to combat the damage caused by free radicals, in order to stabilize the increase of oxidative stress caused in the second gestational trimester.

Incident Coronary Heart Disease After Preeclampsia: Role of Reduced Fetal Growth, Preterm Delivery, and Parity

Background

Preeclampsia is a severe pregnancy disorder often complicated by reduced fetal growth or preterm delivery and is associated with long‐term maternal morbidity and mortality. We aimed to assess the association between preeclampsia phenotypes and risk of subsequent coronary heart disease and maternal cardiovascular mortality.

Methods and Results

Women aged 16 to 49 years who gave birth during 1980–2002 and registered in the Medical Birth Registry of Norway were followed prospectively (1–29 years) for an incident major coronary event and mortality through linkage with the Cardiovascular Disease in Norway 1994–2009 (CVDNOR) project and the Norwegian Cause of Death Registry. Preeclampsia was subdivided based on the presence of a child born small for gestational age or preterm delivery. Among 506 350 women with 1 to 5 singleton births, there were 1275 (0.3%) occurrences of major coronary event, 468 (0.1%) cardiovascular deaths, and 5411 (1.1%) deaths overall. Compared with women without preeclampsia, the hazard ratio (95% CI) for major coronary event was 2.1 (1.73–2.65) after preeclampsia alone, 3.3 (2.37–4.57) after preeclampsia in combination with small for gestational age, and 5.4 (3.74–7.74) after preeclampsia in combination with preterm delivery. Analyses distinguishing women with 1 (n=61 352) or >1 (n=281 069) lifetime pregnancy and analyses with cardiovascular mortality as outcome followed the same pattern.

Conclusions

The occurrence of major coronary events was increased among women with preeclampsia and highest for preeclampsia combined with a child born small for gestational age and/or preterm delivery.

Comparison of adverse perinatal outcomes after single-needle and double-needle CVS techniques

OBJECTIVE

To determine the impact of the chorion villus sampling (CVS) technique on adverse perinatal outcomes.

METHODS

In this case-control study, 412 women who underwent CVS at 11-14 weeks of gestation and 231 women who did not undergo any invasive procedure were retrospectively evaluated. The women in the CVS group were further divided into two groups according to the use of single-needle technique (n=148) vs. double-needle technique (n=264). The adverse outcomes were compared between controls and the two CVS groups, and regression analysis was used to determine the significance of independent contribution.

RESULTS

The rate of preeclampsia for the control group was 2.2%, for the double-needle group was 3% and for the single-needle group was 8.1%. CVS with single-needle technique was found to be an independent and statistically significant risk factor for preeclampsia [odds ratio (OR)=2.1, 95% confidence interval (CI); 1.4-2.7, P=0.008].

CONCLUSION

The risk of preeclampsia after CVS appears to be increased with single-needle technique compared with double-needle technique.

The role of syncytins in human reproduction and reproductive organ cancers

Human life begins with sperm and oocyte fusion. After fertilization, various fusion events occur during human embryogenesis and morphogenesis. For example, the fusion of trophoblastic cells constitutes a key process for normal placental development. Fusion in the placenta is facilitated by syncytin 1 and syncytin 2. These syncytins arose from retroviral sequences that entered the primate genome 25 million and more than 40 million years ago respectively. About 8% of the human genome consists of similar human endogenous retroviral (HERVs) sequences. Many are inactive because of mutations or deletions. However, the role of the few that remain transcriptionally active has not been fully elucidated. Syncytin proteins maintain cell-cell fusogenic activity based on ENV: gene-mediated viral cell entry. In this review, we summarize how syncytins and their receptors are involved in fusion events during human reproduction. The significance of syncytins in tumorigenesis is also discussed.

Prediction of adverse pregnancy outcomes using uterine artery Doppler imaging at 22-24 weeks of pregnancy: A North Indian experience

OBJECTIVE

The aim of this study was to assess the predictive value of uterine artery Doppler imaging at 22-24 weeks of gestation for adverse pregnancy outcomes.

MATERIALS AND METHODS

This was a prospective study in which uterine artery Doppler was performed at 22-24 weeks of gestation in 165 pregnant women with singleton pregnancies. A pulsatility index (PI) more than 1.45 or bilateral uterine notching was labeled as abnormal Doppler. The pregnancy outcome was assessed in terms of normal outcome, preeclampsia, fetal growth restriction (FGR), low birth weight, spontaneous preterm delivery, oligohydramnios, fetal loss or at least one adverse outcome.

RESULTS

Out of 165 patients, 35 (21.2%) had abnormal second trimester uterine artery Doppler. In pregnancies that resulted in preeclampsia (PE), (n=21), FGR, (n=21), and low birth weight (n=39), the median uterine artery PI was higher (1.52, 1.41, and 1.27 respectively). In the presence of abnormal Doppler, the risk of PE [OR=10.7, 95% confidence interval (CI): (3.91-29.1); p<0.001], FGR [OR=4.34, 95% CI: (1.62-11.6); p=0.002], low birth weight [OR=6.39, 95% CI: (3.16-12.9); p<0.001] and the risk of at least one obstetric complication [OR=8.73, 95% CI: (3.5-21.3); p<0.001] was significantly high. The positive predictive value of abnormal uterine artery Doppler was highest for preeclampsia (36.84%) among all adverse pregnancy outcomes assessed.

CONCLUSION

Uterine artery Doppler ultrasonography at 22-24 weeks of gestation is a significant predictor of at least one adverse pregnancy outcome, with the highest prediction for preeclampsia.

Association between thrombophilia gene polymorphisms and preeclampsia: a meta-analysis

OBJECTIVE

To estimate the relationship between the risk of preeclampsia and two thrombophilia gene single-nucleotide polymorphisms (SNPs), the factor V G1691A SNP and the prothrombin G20210A SNP.

DATE SOURCES

A systematic search of the English-language literature up to November 2012 was performed using Medline and EMBASE. Search terms included "preeclampsia," "thrombophilia," "factor V Leiden," "prothrombin gene 20210," and their combinations.

RESULT(S)

Thirty-seven studies with 5048 preeclampsia patients and 6796 controls were included in the meta-analysis. We found that the prothrombin G20210A polymorphism was associated with an increased risk of all preeclampsia (pooled odds ratio (OR) = 1.81, 95% confidence interval (CI) 1.25-2.63) and severe preeclampsia (pooled OR = 3.02, 95%CI 2.06-4.45). Meanwhile, the pooled OR for the association between factor V Leiden and all preeclampsia was 1.60 (95%CI 1.28-2.00) and 2.45 (95%CI 1.63-3.69) for the cases of severe preeclampsia.

CONCLUSION(S)

This meta-analysis supports that the factor V G1691A SNP and the prothrombin G20210A SNP are associated with an increased risk for both preeclampsia overall and severe preeclampsia.

Increased decidual mRNA expression levels of candidate maternal pre-eclampsia susceptibility genes are associated with clinical severity

INTRODUCTION

Pre-eclampsia (PE) has a familial association, with daughters of women who had PE during pregnancy having more than twice the risk of developing PE themselves. Through genome-wide linkage and genetic association studies in PE-affected families and large population samples, we previously identified the following as positional candidate maternal susceptibility genes for PE; ACVR1, INHA, INHBB, ERAP1, ERAP2, LNPEP, COL4A1 and COL4A2. The aims of this study were to determine mRNA expression levels of previously identified candidate maternal pre-eclampsia susceptibility genes from normotensive and severe PE (SPE) pregnancies and correlate mRNA expression levels with the clinical severity of SPE.

METHODS

Third trimester decidual tissues were collected from both normotensive (n = 21) and SPE pregnancies (n = 24) and mRNA expression levels were determined by real-time PCR. Gene expression was then correlated with several parameters of clinical severity in SPE. Statistical significance was determined by Mann-Whitney U test and Spearman's Correlation.

RESULTS

The data demonstrate significantly increased decidual mRNA expression levels of ACVR1, INHBB, ERAP1, ERAP2, LNPEP, COL4A1 and COL4A2 in SPE (p < 0.05). Increased mRNA expression levels of several genes - INHA, INHBB, COL4A1 and COL4A2 were correlated with earlier onset of PE and earlier delivery of the fetus (p < 0.05).

CONCLUSION

These results suggest altered expression of maternal susceptibility genes may play roles in PE development and the course of disease severity.

Associations between ambient air pollution and Hypertensive Disorders of Pregnancy

BACKGROUND

Exposure to ambient air pollution is linked to adverse pregnancy outcomes. Previous reports examining the relationship between ambient air pollution and Hypertensive Disorders of Pregnancy have been inconsistent.

OBJECTIVES

We evaluated the effects of ambient air pollution on the odds of Hypertensive Disorder of Pregnancy and whether these associations varied by body mass index (BMI).

METHODS

We conducted a retrospective, case-control study among 298 predominantly Hispanic women (136 clinically confirmed cases) who attended the Los Angeles County+University of Southern California Women's and Children's Hospital during 1996-2008. Trimester-specific carbon monoxide (CO), nitrogen dioxide (NO2), ozone (O3), and particulate matter with aerodynamic diameter <10 μm and <2.5 μm (PM10, PM2.5) exposure were estimated based on 24-hour exposure level at residential address. Logistic regression models were fitted to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for two standard deviation increase in exposure levels.

RESULTS

Exposures to CO and PM2.5 in the 1st trimester were significantly associated with Hypertensive Disorders of Pregnancy, and these associations were modified by BMI. In non-obese women (BMI <30), 1st trimester exposures to PM2.5 and CO were significantly associated with increased odds of Hypertensive Disorder of Pregnancy (ORs per 2-standard deviation increase in PM2.5 (7 μg/m(3)) and CO (1 ppm) exposures were 9.10 [95% CI: 3.33-24.6] and 4.96 [95% CI: 1.85-13.31], respectively). Additionally, there was a significantly positive association between exposure to O3 in the 2nd trimester and Hypertensive Disorder of Pregnancy (OR per 15 ppb=2.05; 95% CI: 1.22-3.46).

CONCLUSION

Among non-obese women, 1st trimester exposure to PM2.5 and carbon monoxide are associated with increased odds of Hypertensive Disorder of Pregnancy.

Genetic admixture and risk of hypertensive disorders of pregnancy among Latinas in Los Angeles County

BACKGROUND

Latinos are a heterogeneous population in terms of demographics, culture, and genetic admixture from three racial groups (white, African, and Native American). This study examines the role of genetic ancestry and environmental risk factors in the risk of hypertensive disorder of pregnancy among Latinas in Los Angeles County.

METHODS

Gestational hypertension, preeclampsia, eclampsia, or hemolysis, elevated liver enzymes, and low platelets (HELLP) syndrome cases (n = 125), plus unaffected controls (n = 161), were recruited from Los Angeles County + University of Southern California Women's and Children's Hospital from 1999 through 2008. Diagnoses were confirmed with extensive chart review. Personal information, demographics, and biospecimens were collected from all participants. Ancestry informative markers were used to estimate genetic ancestry proportions.

RESULTS

After adjusting for European ancestry and key risk factors, African ancestry was positively associated with hypertensive disorders of pregnancy risk for the highest vs. the lowest quartiles of African ancestry (odds ratio = 2.6 [95% confidence interval = 1.1-6.1]). This association was stronger among women born in Mexico with parents born in Mexico (4.3 [1.4-13]). The results from generalized additive models showed a positive association between joint European/African ancestry and hypertensive disorders of pregnancy risk and an inverse association between Native American ancestry and risk. These associations were stronger among women of Mexican origin.

CONCLUSION

Our findings suggest that higher Native American ancestry among Latinas may protect against hypertensive disorders of pregnancy. Further studies are needed to determine whether this protective effect is driven by specific alleles present in this population or by other risk factors that correlate with Native American ancestry.

Reduced syncytin-1 expression levels in placental syndromes correlates with epigenetic hypermethylation of the ERVW-1 promoter region

Terminal differentiation of villous cytotrophoblasts (CT) ends in formation of the multinucleated syncytiotrophoblast representing the fetal-maternal interface. Aberrations during this cell-fusion process are associated with Intrauterine Growth Restriction (IUGR), Preeclampsia (PE) and High Elevated Liver and Low Platelets (HELLP) Syndrome. Syncytin-1, the envelope gene of the human Endogenous Retrovirus ERVW-1, is one of the most important genes involved in cell-fusion and showed decreased gene expression during these pathological pregnancies. The aim of this study was to determine the methylation pattern of the entire promoter of ERVW-1 and to correlate these findings with the expression profile of Syncytin-1 in the placental syndromes. 14 isolated villous cytotrophoblasts from control (n = 3), IUGR (n = 3), PE (n = 3), PE/IUGR (n = 3) and HELLP/IUGR (n = 2) placentae were used to determine the mean methylation level (ML) for the ERVW-1 promoter region. ML rose significantly from 29% in control CTs to 49% in IUGR, 53% in PE, 47% in PE/IUGR and 64% in HELLP/IUGR indicating an epigenetic down-regulation of Syncytin-1 by promoter hypermethylation. DNA demethylation of the trophoblast like cell lines BeWo, JEG-3 and JAR with 5-AZA-2′desoxycytidine (AZA) showed an increased Syncytin-1 expression and fusion ability in all cell lines. Promoter activity of the 5′LTR could be inhibited by hypermethylation 42-fold using a luciferase based reporter-gene assay. Finally overexpression of the methyltransferases DNMT3a and LSH could be responsible for a decreased Syncytin-1 expression by promoter hypermethylation of ERVW-1. Our study linked decreased Syncytin-1 expression to an epigenetic hypermethylation of the entire promoter of ERVW-1. Based on our findings we are predicting a broad aberrant epigenetic DNA-methylation pattern in pathological placentae affecting placentogenesis, but also the development of the fetus and the mother during pregnancy.

FOLATE METABOLISM AND PREECLAMPSIA

Preeclampsia (PE) is a multisystem disorder of human pregnancy, affecting about 6% of all pregnancies worldwide, and is one of the leading causes of maternal and infant morbidity and mortality. Despite decades of research into the pathogenesis of this complex disease, the underlying mechanisms remain unclear. As a result, the options for prevention and management of PE are limited. In recent years, there has been a growing body of evidence suggesting that folate deficiency is associated with PE, and folic acid supplementation may reduce the risk of developing PE in certain populations. Folate contributes to cell division and growth, and folate metabolism is involved in a large number of physiological and pathophysiological processes in human development. Sufficient supply of folate is therefore particularly important during pregnancy. Nevertheless, the exact mechanisms of folic acid deficiency increasing the risk of developing PE are still unclear. This article reviews what is understood about the aetiology of PE and the relationship between folate metabolism and PE so as to enhance further discussions on the subject.

The Ala-9Val (Mn-SOD) and Arg213Gly (EC-SOD) polymorphisms in the pathogenesis of preeclampsia in Romanian women: association with the severity and outcome of preeclampsia

OBJECTIVE

To check whether individual or combined mutated genotypes for Ala-9Val (Mn-SOD) and Arg213Gly (EC-SOD) are associated with preeclampsia; to check the influence of the mutated genotypes on the degree of severity and perinatal outcome of preeclampsia.

METHODS

We genotyped 97 pregnant women (47 with preeclampsia and 50 normal pregnant women) using PCR-RFLP analysis.

RESULTS

The Val/Val (Mn-SOD) genotype (OR 5.99, p = 0.004) but not the Gly/Gly (EC-SOD) genotype (OR 4.23, p = 0.027) was significantly associated with preeclampsia. Higher frequency of both polymorphisms in women with preeclampsia (42.55%) compared to normal pregnant women (8%). Higher frequency of women diagnosed with PIH (27.27%, OR 4.31), mild (50%, OR 11.5) and severe preeclampsia (37.5%, OR 6.9) positive for both polymorphism compared to control women (8%). There was a statistically significant difference in gestational age at delivery according to Mn-SOD (Ala/Ala vs. Val/Val, 39 ± 1.41 weeks vs. 32.77 ± 3.7 weeks) and EC-SOD genotypes (Arg/Arg vs. Gly/Gly, 37.05 ± 3.18 weeks vs. 31.5 ± 3.84 weeks). There also was a statistically significant difference in birth weight according to Mn-SOD (grams, Ala/Ala vs. Val/Val, 3080 ± 481.66 vs. 2376.92 ± 916.88) and EC-SOD genotypes (grams, Arg/Arg vs. Gly/Gly, 2934.09 ± 662.14 vs. 2080 ± 721.19).

CONCLUSIONS

Our study demonstrates a relationship between these two mutated genes, the clinical severity and the perinatal outcome of preeclampsia.

Reduced expression of both syncytin 1 and syncytin 2 correlates with severity of preeclampsia

Human endogenous retroviruses (HERVs) represent up to 8% of the human genome and express several of its genes in the placenta. Studies have demonstrated that HERV envelope proteins syncytins 1 and 2 play a crucial role in trophoblast fusion and placenta development. Here, we compared the levels of placental expression of syncytins with the severity of preeclampsia (PE) symptoms. Confocal microscopy experiments indicated a pronounced deficiency in cellular fusion in trophoblast cells from patients with PE when compared to controls. As determined by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) and Western blot analyses, syncytin mRNA and protein levels were decreased in PE placentas versus controls. Interestingly, syncytin 2 levels were more importantly impaired than syncytin 1. Our results further highlighted the existence of a correlation between the extent of the decrease in the expression levels of both fusogenic proteins and the degree of severity of PE symptoms. These HERV proteins could thereby be used as potential markers for the early diagnosis of PE.

Maternal/newborn genotype contribution of the renin–angiotensin system (Met235Thr, Thr174Met, I/D-ACE, A2350G-ACE, A1166C-AT2R1, C3123A- AT2R2, 83A/G-REN) to the risk of pre-eclampsia: a Romanian study

Introduction: We evaluated the association of the mutated genotypes Met235Thr-AGT, Thr174Met-AGT, I/D-ACE, A2350G-ACE, A1166C-AT2R1, C3123A-AT2R2, 83A/G-REN with the risk and outcome of pre-eclampsia; we also investigated whether genes in newborns increase maternal risk of pre-eclampsia.

Materials and methods: Thirty-six pairs of pre-eclamptic women and their newborns were genotyped, along with 71 pairs of controls (mothers/newborns) using PCR-RFLP analysis.

Results: The Thr235/Thr235 (OR 3.44, p = 0.01), DD (OR 2.66, p = 0.039), CC1166 (OR 5.56, p = 0.04), AA3123 (OR 3.77, p = 0.03) and GG83 (OR 8.32, p = 0.006) genotypes are significantly associated with pre-eclampsia. Women with pre-eclampsia positive for Met235Thr (34.64 ± 3.92 weeks vs. 38 ± 2 weeks), Thr174Met (32.58 ± 3.92 weeks vs. 36.38 ± 3.25 weeks), I/D (34.47 ± 3.67 weeks vs. 38.33 ± 3.5 weeks) delivered at a significant lower gestational age compared with pre-eclamptic women with a normal genotype. Newborns from women with pre-eclampsia positive for Thr174Met (2190 ± 820.21 g vs. 2702.08 ± 967.23 g), I/D (2399.33 ± 938.38 g vs. 3191.66 ± 684.40 g) had a significant lower birth weight compared with newborns from women with normal pregnancies. When both the mother and the newborn were positive for Met235Thr, I/D, A2350G, A1166C or 83A/G polymorphisms, the risk for pre-eclampsia was significantly increased at 6.67 ( p < 0.01), 5 ( p < 0.01), 3.33 ( p = 0.006), 2.72 ( p = 0.04) and 7.8 ( p < 0.01), respectively.

Conclusions: The results of our study confirm that, in pre-eclampsia, both maternal and newborn genetic variations implicated in blood pressure regulation are important.

Investigation of maternal effects, maternal-fetal interactions and parent-of-origin effects (imprinting), using mothers and their offspring

Many complex genetic effects, including epigenetic effects, may be expected to operate via mechanisms in the inter-uterine environment. A popular design for the investigation of such effects, including effects of parent-of-origin (imprinting), maternal genotype, and maternal-fetal genotype interactions, is to collect DNA from affected offspring and their mothers (case/mother duos) and to compare with an appropriate control sample. An alternative design uses data from cases and both parents (case/parent trios) but does not require controls. In this study, we describe a novel implementation of a multinomial modeling approach that allows the estimation of such genetic effects using either case/mother duos or case/parent trios. We investigate the performance of our approach using computer simulations and explore the sample sizes and data structures required to provide high power for detection of effects and accurate estimation of the relative risks conferred. Through the incorporation of additional assumptions (such as Hardy-Weinberg equilibrium, random mating and known allele frequencies) and/or the incorporation of additional types of control sample (such as unrelated controls, controls and their mothers, or both parents of controls), we show that the (relative risk) parameters of interest are identifiable and well estimated. Nevertheless, parameter interpretation can be complex, as we illustrate by demonstrating the mathematical equivalence between various different parameterizations. Our approach scales up easily to allow the analysis of large-scale genome-wide association data, provided both mothers and affected offspring have been genotyped at all variants of interest. Genet. Epidemiol. 35:19–45, 2011. © 2010 Wiley-Liss, Inc.

Trophoblast differentiation, fetal growth restriction and preeclampsia

The number of hypotheses trying to decipher the etiologies of preeclampsia and fetal growth restriction (FGR) is still increasing. However, for preeclampsia the actual knowledge we have is that the placenta is a prerequisite for the development of the syndrome. The recent years have seen a shift in understanding of the causes of preeclampsia from mostly focusing on the extravillous trophoblast towards the dysregulation of villous trophoblast development and maintenance. It seems as if a failure of the villous syncytiotrophoblast differentiation results in abnormal release of non-apoptotic fragments into maternal blood. In preeclampsia such necrotic or aponecrotic fragments can be found in maternal blood systemically and seem to be causative in the development of the inflammatory response of the mother. In cases with fetal growth restriction (FGR) extravillous trophoblast fails to adequately transform uterine spiral arteries. However, in FGR cases abnormal development of villous cytotrophoblast may have an impact on fetal nutrition without the induction of an inflammatory response of the mother. It is still unclear why the villous trophoblast fails to achieve an adequate turnover both in preeclampsia and in FGR. However, the detection of new biomarkers for preeclampsia such as placental protein 13 (PP13) has helped in clarifying the issue of when the syndrome starts to develop. PP13 levels in maternal serum are significantly altered already at six to seven weeks of gestation in women subsequently developing preeclampsia. Thus, there needs to be a very early alteration of villous development in such placentas. Herein the changes in villous trophoblast in preeclampsia and FGR are compared and differences between both scenarios are presented.

The association between preeclampsia and placental disruption induced by chorionic villous sampling

OBJECTIVES

The objectives of this study were (1) to evaluate if the elevation of maternal serum alpha-feto protein (MSAFP) and pregnancy-associated placental protein-A (PAPP-A) in the maternal blood after chorionic villous sampling (CVS) is associated with a higher preeclampsia (PE) rate and (2) to verify the clinical utility of the analytes elevation for predicting PE.

METHODS

A prospective study on 106 subjects who underwent CVS was performed. At the time of CVS, two blood samples were obtained for MSAFP and PAPP-A dosage, the first just before the procedure, and the second one 30 min after the procedure. Cases with abnormal karyotype, major anomalies or preterm delivery were subsequently excluded. The ratio between the two samples was calculated as Sigma (MSAFP or PAPP-A post-CVS/MSAFP or PAPP-A pre-CVS) and it was related to subsequent occurrence of PE.

RESULTS

The rate of PE was 5.7% (6/106). Both MSAFP and PAPP-A levels were higher after than before CVS (median ratio = 8.33 and 1.08, respectively). Cases developing PE had significantly higher MSAFP ratio (11.6 vs 7.4, p-value = 0.04) and PAPP-A ratio (1.13 vs 1.08, p-value = 0.009) than those who did not develop PE. Receiver operating characteristic curve analysis showed that PAPP-A ratio was a better predictor of subsequent PE than MSAFP ratio: at a fixed false positive rate of 10%, the detection rates for MSAFP and PAPP-A ratios were 33 and 50%, respectively.

CONCLUSION

The elevation of MSAFP and PAPP-A observed with CVS is associated with increased risk of subsequent PE. The ability of such increases to predict PE appears to be modest.

Likelihood ratio tests for maternal and fetal genetic effects on obstetric complications

It is well recognized that both maternal and fetal genes could contribute to susceptibility for obstetric complications. Logistic regression models are usually adopted to model the separate or joint action of maternal and fetal loci with case-control data. The standard likelihood ratio tests (LRTs) can be used to test the significance of appropriate odds ratio parameters. This method, although simple to implement, fails to exploit a unique feature of genetic epidemiology studies of obstetric complications. Specifically, it does not take into consideration the correlation between the maternal and offspring genomes. We propose novel LRT that take advantage of this information by incorporating the fact that half of a child's genome is inherited from the mother. Our methods have substantially improved power for detecting marginal, main, and interactive maternal and fetal genotype effects, as evidenced by results from extensive simulation studies. We demonstrate our new methods by applying them to the analysis of data from a pilot study of preeclampsia.

Testing Hardy-Weinberg equilibrium using mother-child case-control samples

Genetic association studies of obstetric complications may genotype case and control mothers, or their respective newborns, or both case-control mothers and their children. The relatively high prevalence of many obstetric complications and the availability of both maternal and offspring's genotype data have provided motivation to study new methods for testing for deviations from Hardy-Weinberg equilibrium (HWE). We propose four novel test statistics, each of which uses a different type of data as follows: (1) a test using maternal case-control genotype data, (2) a test using offspring genotype data, (3) a combination of the first and second tests, and (4) a test based on the joint classification of case-control maternal-child genotype data. The selection of case and control mothers (and thus their children) is accounted for by weighting both maternal and child contributions to the test statistics with sampling probabilities. Our tests thus do not require that the phenotype be rare as is the case for HWE tests using only controls, and are particularly suitable for genetic association studies of relatively common complications such as premature birth. The third and fourth tests described above utilize both maternal and child genotype data and appropriately account for the correlation between maternal and child genotypes. On the basis of extensive simulation studies to compare the type-I error and power for proposed tests, we recommend the third combined test statistic for routine use in the analysis of case-control studies of mother-child pairs.

Maternal and fetal variants in the TGF-beta3 gene and risk of pregnancy-induced hypertension in a predominantly Latino population

OBJECTIVE

We sought to determine whether polymorphisms in the transforming growth factor (TGF)-beta3 gene are associated with risk of pregnancy-induced hypertension (PIH) in case-control mother-baby dyads.

STUDY DESIGN

Patients (n = 136) and control subjects (n = 169) were recruited from our hospital. We genotyped 4 TGF-beta3 polymorphisms and examined association with PIH using logistic regression, adjusting for parity, maternal age, gestational age at delivery, fetal (or maternal) genotypes for the polymorphism in question, and the 3 other polymorphisms within the TGF-beta3 gene.

RESULTS

Only 1 of the TGF-beta3 polymorphisms (rs11466414) was associated with PIH. Mothers who carried a baby with a minor allele were at decreased risk (odds ratio(multi-locus adj), 0.32; 95% confidence interval, 0.14-0.77). Maternal TGF-beta3 variants had no effect on risk of PIH.

CONCLUSION

A fetal TGF-beta3 polymorphism (rs11466414) is associated with PIH in a predominantly Hispanic population.

Preeclampsia: the role of angiogenic factors in its pathogenesis

Preeclampsia, a systemic syndrome of pregnancy clinically characterized by new onset of proteinuria and hypertension, is associated with significant morbidity and mortality to both mothers and fetuses. The pathogenesis of preeclampsia has been enigmatic; this review will focus on understanding the origins of this disorder. Preeclampsia originates in the placenta, starting with inadequate cytotrophoblast invasion and ending with widespread maternal endothelial dysfunction. Production of placental anti-angiogenic factors, specifically soluble fms-related tyrosine kinase 1 and soluble endoglin, have been shown to be upregulated in preeclampsia. These placental anti-angiogenic factors are released into the maternal circulation; their actions disrupt the maternal endothelium and result in hypertension, proteinuria, and the other systemic manifestations of preeclampsia. The molecular basis for placental dysregulation of these pathogenic factors remains unknown, remains unknown. Hypoxia is likely an important regulator. Other factors such as alterations in the renin-angiotensin-aldosterone axis, immune maladaption, excessive shedding of trophoblast debris, oxidative stress, and genetic factors likely contribute to the pathogenesis of the abnormal placentation. As of 2009, the only successful treatment for preeclampsia is delivery. No definitive preventive strategies have been identified. However, several of the recent observations related to phenotypic causality provide stimuli for the development of novel therapies.

Microarray technology applied to the complex disorder of preeclampsia

Preeclampsia is a life-threatening perinatal complication with unknown etiology. Microarray technology has characterized global gene expression in complex disorders such as preeclampsia. Nursing research and future practice may incorporate findings from microarray analyses to identify susceptibility to and prevent disease, to diagnose early, and to design and monitor personalized therapies. This overview of microarray technology, with emphasis on how it can inform genomics of preeclampsia, may provide concepts to improve future maternal-neonatal nursing care.

Genes and the preeclampsia syndrome

Preeclampsia is specific to pregnancy and is still a leading cause of maternal and perinatal mortality and morbidity, affecting about 3% of women, but the underlying pathogenetic mechanisms still remain unclear. Immune maladaptation, placental ischemia and increased oxidative stress represent the main components discussed to be of etiologic importance, and they all may have genetic implications. Since the familial nature of preeclampsia is known for many years, extensive research on the genetic contribution to the pathogenesis of this severe pregnancy disorder has been performed. In this review, we will overview the linkage and candidate gene studies carried out so far as well as summarize important historical notes on the genetic hypotheses generated in preeclampsia research. Moreover, the influence of maternal and fetal genes and their interaction as well as the role of genomic imprinting in preeclampsia will be discussed.

Impaired cytotrophoblast cell-cell fusion is associated with reduced Syncytin and increased apoptosis in patients with placental dysfunction

Preeclampsia (PE), Hemolysis Elevated Liver Enzymes and Low Platelets (HELLP)-syndrome, and intrauterine growth restriction (IUGR) are associated with abnormal placentation. In early pregnancy, placental cytotrophoblasts fuse and form multinuclear syncytiotrophoblasts. The envelope gene of the human endogenous retrovirus-W, Syncytin, is a key factor for mediating cell-cell fusion of cytotrophoblasts. This study investigated clinical parameters of PE and HELLP-associated IUGR and analyzed the cell-cell fusion index and beta-human chorionic gonadotropin (beta-hCG) secretion of cytotrophoblasts isolated and cultured from placentas of these patients. In addition, we performed absolute quantitation of Syncytin and determined the apoptosis rate in both cultured cytotrophoblasts and placental tissues. Cultured cytotrophoblasts from PE and HELLP-associated IUGR correlated with a pronounced lower cell-cell fusion index, 1.8- and 3.6-fold; less nuclei per syncytiotrophoblast, 1.4- and 2.0-fold; a significantly decreased beta-hCG secretion, 4.3- and 17.2-fold and a reduction of Syncytin gene expression, 8.1 (P = 0.019) and 222.7-fold (P = 0.011) compared with controls, respectively. In contrast, a significantly 2.3-fold higher apoptosis rate was observed in cultured PE/IUGR cytotrophoblasts (P = 0.043). Importantly, Syncytin gene expression in primary placental tissues of PE/IUGR was 5.4-fold lower (P = 0.047) and in HELLP/IUGR 10.6-fold lower (P = 0.019) along with a 1.8- and 1.9-fold significant increase in the apoptosis rate compared with controls, respectively. Low Syncytin expression in both cultured cytotrophoblasts and primary tissues from pathological placentas supports an intrinsic placenta-specific deregulation of cell-cell fusion in the formation of syncytiotrophoblasts leading to increased apoptosis. These processes could contribute to the development and severity of PE and HELLP-associated IUGR.

Chorionic villus sampling and risk for hypertensive disorders of pregnancy

OBJECTIVE

This study was undertaken to evaluate the relationship between chorionic villus sampling at 10-13 weeks' gestational age and hypertensive disorders of pregnancy.

STUDY DESIGN

The prevalence of hypertensive disorders of pregnancy in women with singleton gestations, undergoing transcervical or transabdominal chorionic villus sampling between 10 weeks 0 days' and 13 weeks 6 days' gestational age was compared with that of control women with singleton gestations having first-trimester screening with nuchal translucency and biochemistry between 11 weeks 0 days' and 13 weeks 6 days' gestational age. Patients having invasive prenatal diagnosis (chorionic villus sampling or amniocentesis) were excluded from the control group. All patients delivered at Cedars-Sinai Medical Center.

RESULTS

There were 1540 women who had chorionic villus sampling and 840 controls. Hypertensive disorders of pregnancy were diagnosed in 76 (4.9%) patients in the chorionic villus sampling group and in 37 (4.4%) of the controls (chi2 = 0.34, P = .31).

CONCLUSION

Chorionic villus sampling at 10 to 13 weeks' gestational age does not appear to increase the overall risk for hypertensive disorders of pregnancy. However, there appears to be an association between chorionic villus sampling and severe hypertensive disorders including severe preeclampsia, eclampsia, and hemolysis, elevated liver enzymes, and low platelet count syndrome.

Candidate-gene association study of mothers with pre-eclampsia, and their infants, analyzing 775 SNPs in 190 genes

Pre-eclampsia (PE) affects 5-7% of pregnancies in the US, and is a leading cause of maternal death and perinatal morbidity and mortality worldwide. To identify genes with a role in PE, we conducted a large-scale association study evaluating 775 SNPs in 190 candidate genes selected for a potential role in obstetrical complications. SNP discovery was performed by DNA sequencing, and genotyping was carried out in a high-throughput facility using the MassARRAY(TM) System. Women with PE (n = 394) and their offspring (n = 324) were compared with control women (n = 602) and their offspring (n = 631) from the same hospital-based population. Haplotypes were estimated for each gene using the EM algorithm, and empirical p values were obtained for a logistic regression-based score test, adjusted for significant covariates. An interaction model between maternal and offspring genotypes was also evaluated. The most significant findings for association with PE were COL1A1 (p = 0.0011) and IL1A (p = 0.0014) for the maternal genotype, and PLAUR (p = 0.0008) for the offspring genotype. Common candidate genes for PE, including MTHFR and NOS3, were not significantly associated with PE. For the interaction model, SNPs within IGF1 (p = 0.0035) and IL4R (p = 0.0036) gave the most significant results. This study is one of the most comprehensive genetic association studies of PE to date, including an evaluation of offspring genotypes that have rarely been considered in previous studies. Although we did not identify statistically significant evidence of association for any of the candidate loci evaluated here after adjusting for multiple testing using the false discovery rate, additional compelling evidence exists, including multiple SNPs with nominally significant p values in COL1A1 and the IL1A region, and previous reports of association for IL1A, to support continued interest in these genes as candidates for PE. Identification of the genetic regulators of PE may have broader implications, since women with PE are at increased risk of death from cardiovascular diseases later in life.

Decreased ovarian reserve relates to pre-eclampsia in IVF/ICSI pregnancies

BACKGROUND

Pre-eclampsia affects 2-10% of all pregnancies and is a major cause of maternal and fetal morbidity and mortality. As compared with the general population, IVF pregnancies are associated with a 2.7-fold risk of pre-eclampsia. An advanced age and associated subfertility in the IVF group reflects a general decrease in ovarian reserve, which itself has been linked to cardiovascular disease. We tested the hypothesis that decreased ovarian reserve is associated with pre-eclampsia as a vascular complication in IVF/ICSI pregnancies.

METHODS

In this retrospective case-control study, 41 cases with a history of pre-eclampsia were compared to 82 matched controls without hypertension or (pre)eclampsia. All pregnancies were established after IVF or ICSI. Several indicators of ovarian reserve such as variables related to basal ovarian function and response to hyperstimulation were compared in both the groups by multivariate analysis. The condition of the neonates was evaluated as well.

RESULTS

A higher amount of total administered FSH and FSH per day, together with a lower number of obtained oocytes during IVF treatment, were associated with an increased risk to pre-eclampsia in a subsequent pregnancy. The administered FSH per follicle and per obtained oocyte showed even stronger relationships, the latter having the best predictive value. Neonatal outcome was comparable between the groups.

CONCLUSION

Diminished responsiveness of the ovaries to FSH stimulation in an IVF cycle, reflecting decreased ovarian reserve, is associated with an increased risk of developing pre-eclampsia in a subsequent pregnancy.

Searching for genetic clues to the causes of pre-eclampsia

Pre-eclampsia and its related syndromes are significant causes of maternal and fetal death, but much remains unclear about the underlying disease mechanisms. Epidemiological research has consistently demonstrated a familial predisposition to pre-eclampsia, which has encouraged genetic research in this area. The goal is the discovery of susceptibility genes which will inform understanding of the pathophysiology of pre-eclampsia, and may prove to be targets for therapeutic or preventative strategies. This review examines the application of molecular technologies to the search for genetic clues in pre-eclampsia and emphasizes the importance of integrative approaches. The results of recent genome-wide linkage studies have been particularly encouraging, identifying a number of loci which merit closer examination. Candidate gene studies have proved less fruitful, generating conflicting and inconclusive results. Possible explanations and remedies for this deficiency are discussed with a view to stimulating closer collaboration between researchers in this field.

Mapping the theories of preeclampsia: the need for systematic reviews of mechanisms of the disease

Preeclampsia, a major cause of morbidity in pregnancy, is still a disease of unknown cause, despite considerable research in recent times. We believe that progress in understanding the disorder would be enhanced if the systematic review methodology, similar to that used to assess data from clinical trials, is applied to studies that investigate the many theories advanced to explain its cause. This article discusses the need for and a frame work of such an endeavor. The systematic review approach helps to determine where research should be focused, to prioritize the use of resources, to understand, and then hopefully to conquer a disease that still kills mothers and infants each year, worldwide.

Prediction of pregnancy complications by first-trimester maternal serum PAPP-A and free beta-hCG and with second-trimester uterine artery Doppler

BACKGROUND

Previous studies have shown an association between low first trimester maternal serum free beta-hCG and PAPP-A and subsequent development of pregnancy complications. Similarly, uterine artery Doppler in the late second trimester has shown that high impedance to flow is associated with increased risk for preeclampsia and fetal growth restriction. The objective of this study is to determine whether there is an association between the maternal serum concentration of PAPP-A and free beta-hCG at 11-13(+6) weeks with the uterine artery pulsatility index (PI) at 22-24 weeks, and secondly, to compare the screening characteristics of the two methods in the prediction of adverse pregnancy outcome.

METHODS

Maternal serum PAPP-A and free beta-hCG at 11-13(+6) weeks and uterine artery PI at 22-24 weeks were measured in 4390 women with singleton pregnancies. Pregnancies with chromosomal defects or fetal anomalies were excluded. The biochemical and Doppler measurements were compared between those with normal outcome and those resulting in spontaneous preterm delivery, pre-eclampsia and fetal growth restriction (FGR). Detection rates using a combination of the biochemical and Doppler measurements were investigated.

RESULTS

In the pregnancies resulting in pre-eclampsia (n = 64) and FGR (n = 172), the median PAPP-A was lower (0.844 and 0.813 MoM), the median uterine artery mean PI was higher (1.56 and 1.18) but the median free betahCG was not significantly different (0.923 and 0.933 MoM) than in the normal outcome group. In the preterm delivery group (n = 159), the median free beta-hCG (0.944 MoM) and uterine artery mean PI (1.06) were not significantly different from normal but the median PAPP-A (0.928 MoM) was significantly lower than normal. In screening for pre-eclampsia, the detection rate, for a 5% false-positive rate, was 14.1% for PAPP-A, 54.7% for uterine artery mean PI and 62.1% for a combination of PAPP-A and uterine artery mean PI.

CONCLUSION

Maternal serum PAPP-A at 11-13(+6) of gestation is significantly lower in adverse pregnancy outcomes. The combination of first trimester serum PAPP-A and uterine artery mean PI at 22-24 weeks improves the screening efficacy for the prediction of pre-eclampsia.