Pre-eclampsia-like conditions produced by nitric oxide inhibition: effects of L-arginine, D-arginine and steroid hormones

The aim of this study was to establish that inhibiting nitricoxide (NO) production with N^G-nitro-L-arginine methyl ester(L-NAME) results in high blood pressure conditions in chronicallytreated pregnant rats. To validate the model,the effects ofL-arginine (the substrate for NO) and Darginine (the stereoisomerof L-arginine which is not substrate for NO synthesis) werestudied on blood pressure and fetal weights. The effects ofa progesterone agonist, promegestone (R5020) and 17-oestradiolwere also explored. The NO synthase inhibitor L-NAME was chronicallyinfused s.c. into pregnant rats from day 17 of gestation, eitheralone or with the simultaneous infusion of L-arginine and injectionsof sex steroid hormones (promegestone and oestradiol), compoundsthat may act in the pathogenic pathways of pre-eclampsia. Systolicblood pressure was measured daily. Weight and mortality of pupswere recorded immediately after delivery. Blood pressure waselevated significantly in rats treated with L-NAME for only1 day following infusion; there was a consistent decline duringthe next 3 days of pregnancy followed by a dramatic and significantrise just prior to delivery and post-partum. Fetal weights werereduced significantly in the L-NAMEtreated rats. Co-treatmentof L-NAME-infused rats with L-arginine reversed both the increasein blood pressure and the decrease in fetal weights observedwith L-NAME alone. R5020, but not oestradiol, also reduced bloodpressure and increased fetal weights in the L-NAME-treated animals.NO appears to play essential roles in the regulation of bloodpressure during pregnancy, as well as in fetal perfusion andfetal weights at delivery. This study also indicates that progesterone,and not oestrogen, may regulate the vascular adaptations duringnormal pregnancy. LArginine and progesterone agonists like promegestonemay have beneficial effects on the high blood pressure levelsand reduced fetal weights associated with pre-eclampsia.     

Is there a role for isofurans and neuroprostanes in pre-eclampsia and normal pregnancy?

Pre-eclampsia is a complex disorder of pregnancy that adversely affects the mother and baby. Arachidonic acid and docosahexaenoic acid are essential for fetal development and can undergo free radical oxidation to F(2)-isoprostanes (F(2)-IsoPs) and isofurans (IsoFs); and F(4)-neuroprostanes (F(4)-NeuroPs), respectively. These metabolites may be relevant to pre-eclampsia and fetal development. We examined IsoFs, F(4)-NeuroPs, and F(2)-IsoPs in maternal plasma and cord blood plasma of 23 women with pre-eclampsia and 21 normal pregnancies. Women with pre-eclampsia had significantly elevated maternal IsoFs and F(4)-NeuroPs, but not F(2)-IsoPs. Cord blood F(4)-NeuroPs were elevated among neonates of women with pre-eclampsia. In women with pre-eclampsia, birth weight was predicted by gestation at delivery. The latter was also true in normal pregnancy, but birth weight was negatively related to maternal F(2)-IsoPs, IsoFs, and F(4)-NeuroPs. We have shown that in women with pre-eclampsia, IsoFs and F(4)-NeuroPs are elevated, and cord blood F(4)-NeuroPs are increased. The inverse relationship between maternal F(2)-IsoPs, IsoFs, and F(4)-NeuroPs and birth weight may be relevant as predictors of low birth weight in normal pregnancy. Future studies should examine whether these markers in maternal blood at early stages of pregnancy relate to subsequent maternal, fetal, and neonatal complications.     

Maternal human leukocyte antigen-G polymorphism is not associated with pre-eclampsia in a Chinese Han population

Pre-eclampsia is a multisystem disorder of pregnancy and remains the leading cause of both maternal and fetal morbidity and mortality in many countries. Despite extensive studies, the underlying mechanisms still remain unknown. Besides its restricted expression in the tissues of placenta and its function in regulating immune suppression and in ensuring successful invasion of placental tissues into maternal deciduas, it has been postulated that HLA-G may play a role in modulation of immune tolerance at the fetal-maternal interface. Aberrant HLA-G expression may result in pregnancy disorders that are associated with poor invasion of extravillous cytotrophoblast into maternal spiral arteries, such as pre-eclampsia. Studies have shown that pre-eclampsia is largely under genetic control, but genetic mechanisms underlying the disorder have yet to be determined. In the current study, we focus on the potential role of HLA-G polymorphism in the pathogenesis of pre-eclampsia. Samples were obtained from Chinese Han primiparous women with pre-eclampsia and irrelative normal women, and case-matched placentas were genotyped for the HLA-G polymorphism in the exons 2, 3, and 4, and the 14-base-pair (bp) insertion/deletion polymorphism in the 3'-untranslated region of exon 8 was analyzed separately. The frequency of HLA-G polymorphism in these samples was not significantly different from those of normal controls, indicating that maternal HLA-G polymorphism is not associated with the risk for pre-eclampsia in this Chinese Han population. However, the maternal 14-bp insertion/deletion polymorphism is ethnically different.     

A longitudinal study of maternal plasma insulin-like growth factor binding protein-1 concentrations during normal pregnancy and pregnancies complicated by pre-eclampsia

Insulin-like growth factor binding protein-1 (IGFBP-1) is synthesized by the decidual stroma, and is thought to act locally to inhibit IGF activity and so limit trophoblast invasion. Cross-sectional studies have reported conflicting data on maternal circulating concentrations of IGFBP-1 in early pregnancy before the development of pre-eclampsia. A longitudinal study was performed in 10 women who went on to develop pre-eclampsia and a group of 12 normal pregnant controls, chosen to be similar for maternal age, booking body mass index (BMI) and gestational age. Maternal IGFBP-1 concentrations were measured in plasma obtained at 16, 20, 24, 28, 32 and 36 weeks. Plasma IGFBP-1 concentrations were unchanged over this period in normal pregnancy. In contrast, the concentrations in women who developed pre-eclampsia increased progressively. At 16, 20, and 24 weeks the concentrations were significantly lower compared to normal pregnancy, at 28 and 32 weeks, similar, but by 36 weeks the concentrations were significantly greater than the normal controls. The data show that circulating IGFBP-1 concentrations are lower in early pregnancy before the development of pre-eclampsia. Thus, it is suggested that IGFBP-1-induced inhibition of IGF activity is unlikely to be responsible for the impaired trophoblast invasion observed in pre-eclampsia.     

Adverse reproductive outcomes in urban women with adeno-associated virus-2 infections in early pregnancy

BACKGROUND: We demonstrated recently that adeno-associated virus-2 (AAV-2)DNA was detected significantly more frequently in placentaltrophoblast cells from cases of severe pre-eclampsia than fromnormal term deliveries. Here, we sought to determine if maternalAAV-2 infection early in pregnancy preceded adverse outcomesresulting from placental dysfunction. METHODS: We collected first trimester maternal serum samples and comparedanti-AAV-2 IgM antibody levels (indicating primary infectionor reactivation of latent AAV-2) between controls deliveredat term (n = 106) and three groups of cases: spontaneous abortions(n = 34), spontaneous preterm deliveries (n = 24) and womenwith at least one outcome usually attributed to placental dysfunction,including pre-eclampsia, intrauterine growth restriction (IUGR)or stillbirth (n = 20). The seroprevalence of immunoglobulinG (IgG) antibodies against AAV-2 and IgM antibodies againstviruses that promote AAV-2 replication [adenovirus and cytomegalovirus(CMV)] were also determined. RESULTS: First trimester maternal IgM seropositivity was 5.6 times moreprevalent among pre-eclampsia/IUGR/stillbirth cases (P = 0.0004)and 7.6 times more prevalent among preterm deliveries (P <0.0001) than among controls. CMV and adenovirus IgM antibodiesand chronic AAV-2 infections (IgG seropositivity) were not associatedwith adverse pregnancy outcomes. CONCLUSIONS: Primary or reactivated AAV-2 infection (maternal IgM seropositivity)early in pregnancy was associated with adverse reproductiveoutcomes associated with placental dysfunction, including pre-eclampsia,stillbirth and spontaneous preterm delivery.     

Relationships between maternal plasma leptin, placental leptin mRNA and protein in normal pregnancy, pre-eclampsia and intrauterine growth restriction without pre-eclampsia

Leptin, an adipocyte hormone involved in energy homeostasis, is important in reproduction and pregnancy. Questions yet to be addressed include the source of higher leptin during pregnancy and its relationship to pregnancy outcome and fetal growth. The objective of this study was to investigate the relationship between placental leptin gene expression, placental leptin protein concentration and maternal plasma leptin concentration among control pregnant women, women with pre-eclampsia and women with growth-restricted infants. We also investigated the relationship between placental leptin expression and the placental expression of enzymes involved in cellular lipid balance: fatty acid translocase (CD36), carnitine palmitoyltransferase I (CPT-1B) and lipoprotein lipase (LPL). Placental leptin expression, placental protein and maternal plasma concentration were higher in pre-eclampsia than in controls but not in women with growth-restricted infants. Placental leptin expression and placental protein were higher in the preterm pre-eclamptic subjects, whereas maternal leptin was higher in the term pre-eclamptic subjects. The placental gene expression of CD36, CPT-1B and LPL were not different among the groups. This study suggests that despite similar failed placental bed vascular remodelling in pre-eclampsia and intrauterine growth restriction (IUGR), leptin gene expression is higher only in preterm pre-eclampsia.     

Placental-related diseases of pregnancy: Involvement of oxidative stress and implications in human evolution

Miscarriage and pre-eclampsia are the most common disorders of human pregnancy. Both are placental-related and exceptional in other mammalian species. Ultrasound imaging has enabled events during early pregnancy to be visualized in vivo for the first time. As a result, a new understanding of the early materno-fetal relationship has emerged and, with it, new insight into the pathogenesis of these disorders. Unifying the two is the concept of placental oxidative stress, with associated necrosis and apoptosis of the trophoblastic epithelium of the placental villous tree. In normal pregnancies, the earliest stages of development take place in a low oxygen (O2) environment. This physiological hypoxia of the early gestational sac protects the developing fetus against the deleterious and teratogenic effects of O2 free radicals (OFRs). In miscarriage, development of the placento-decidual interface is severely impaired leading to early and widespread onset of maternal blood flow and major oxidative degeneration. This mechanism is common to all miscarriages, with the time at which it occurs in the first trimester depending on the aetiology. In contrast, in pre-eclampsia the trophoblastic invasion is sufficient to allow early pregnancy phases of placentation but too shallow for complete transformation of the arterial utero-placental circulation, predisposing to a repetitive ischaemia-reperfusion (I/R) phenomenon. We suggest that pre-eclampsia is a three-stage disorder with the primary pathology being an excessive or atypical maternal immune response. This would impair the placentation process leading to chronic oxidative stress in the placenta and finally to diffuse maternal endothelial cell dysfunction.     

Direct placental effects of cigarette smoke protect women from pre-eclampsia: the specific roles of carbon monoxide and antioxidant systems in the placenta

Pre-eclampsia is a hypertensive disorder of pregnancy characterized by shallow placentation, inadequate placental perfusion, localized placental oxidative stress, a heightened maternal inflammatory response and subsequent maternal endothelial dysfunction. This pathophysiology leads to an increase in maternal blood pressure, edema and proteinurea. Interestingly, women who smoke cigarettes throughout pregnancy are at a 33% reduced risk of developing this disorder. The exact mechanisms through which cigarette smoke reduces the risk of pre-eclampsia are not yet understood. We propose that cigarette smoke reduces the risk of developing pre-eclampsia via direct placental effects. In this review we will address, and provide evidence for, our specific hypotheses that: (a) CO increases trophoblast invasion and spiral arteriole remodeling; (b) CO decreases a localized inflammatory response at the level of the decidua; (c) CO increases utero-placental, intra-placental and feto-placental blood flow; (d) CO decreases hypoxia-induced apoptosis of the syncitiotrophoblast layer; (e) CO activates hemoproteins involved in normal endothelial functioning normally acted upon by NO; (f) compound(s) within cigarette smoke result in upregulation of antioxidant systems within the placenta. These various mechanisms of action must be further examined as they may provide valuable keys to novel therapeutic design in the realm of pre-eclampsia research.     

Increased levels of pregnancy-associated plasma protein-A2 in the serum of pre-eclamptic patients

Pregnancy-associated plasma protein-A and -A2 (PAPP-A and -A2) are proteases that cleave insulin-like growth factor-binding proteins (IGFBPs), resulting in local activation of IGF signaling pathways. Here, we examined PAPP-A and -A2 mRNA and protein levels in placenta and maternal sera from women with pre-eclampsia and compared them with samples from uncomplicated pregnancy. PAPP-A2 but not PAPP-A mRNA and protein were elevated in pre-eclamptic placenta (P < 0.01). PAPP-A2 is normally produced in placental syncytiotrophoblast cells and maternal decidua. PAPP-A2 in syncytiotrophoblast cells was dramatically increased in pre-eclampsia. Maternal serum concentrations of PAPP-A2 but not PAPP-A were also significantly elevated in pre-eclampsia as compared with uncomplicated pregnancy. mRNA levels of IGFBP5, a specific substrate for PAPP-A2 protease activity, were also significantly increased, suggesting a potential role for IGFBP5 in fetal and placental growth suppression during pre-eclampsia. However, IGFBP5 protein levels were not increased in placenta from pre-eclampsia, possibly due to cleavage by up-regulated PAPP-A2. These data might imply that PAPP-A2 may be up-regulated in pre-eclamptic pregnancy to compensate for IGFBP5-mediated suppression of the IGF pathway, although final birthweights are still low in pre-eclamptic pregnancy.     

Genetic control of severe pre-eclampsia.

A genetic analysis has been made of published and new data on the familial occurrence of severe pre-eclampsia in primigravid women. This has shown that the condition may be largely a Mendelian recessive one. Bcause the condition occurs only in pregnancy, and because susceptible women cannot otherwise be identified, it is difficult to decide whether the genotype of the parent or of the offspring carried in utero leads to the condition. Data on the incidence of severe pre-eclampsia in the relatives of women who have suffered eclampsia support the maternal genotype hypothesis, while similar data, in which the index cases were women who had had severe pre-eclampsia, are more compatible with the fetal genotype hypothesis. Data on the incidence of the condition in blood relatives of index cases compared to the incidence in their corresponding in-laws are now required. Such a comparison would allow a choice to be made between the two hypotheses if one or the other were correct, or would assess the contribution of each if a genotype X genotype interaction were involved. Recurrent severe pre-eclampsia seems to have the same genetic basis as the more common primigravid type. However, mild, that is non-proteinuric, pre-eclampsia usually seems to be inherited independently of the severe form.     

Defective endovascular trophoblast invasion in the first trimester is associated with increased maternal serum ischemia-modified albumin

BACKGROUND: Ischemia-modified albumin (IMA), a protein elevated in cardiac ischemia, is also increased to supra-physiological levels in early normal pregnancy. This finding supports the hypothesis that normal trophoblast development is stimulated by a hypoxic intrauterine environment. The aim of this study was to examine whether first trimester IMA levels are further elevated with defective trophoblast development. METHODS: Prospective study of healthy women with singleton pregnancies undergoing nuchal translucency assessment at 11-14 weeks. First trimester maternal serum IMA concentrations in those subsequently developing pre-term pre-eclampsia (n = 19) were compared to randomly chosen controls with normal pregnancy outcome (n = 69). RESULTS: Median first trimester serum IMA concentrations were significantly higher in women who subsequently developed pre-eclampsia (median 126.5 kU/L, interquartile range (IQR) 114.33-134.36 kU/L) when compared to those with normal pregnancy outcome (median 115.01 kU/L, IQR 102.29-124.81 kU/L, P = 0.02). CONCLUSIONS: Maternal serum IMA levels are elevated in the first trimester in women with pre-eclampsia, a clinical manifestation of defective endovascular trophoblast development. This suggests that abnormally high intrauterine hypoxia and subsequent reperfusion oxidative damage may be associated with defective trophoblast development. First trimester serum IMA may be a potential biomarker for abnormal placental development.     

Insulin-like factor 3 levels in amniotic fluid of human male fetuses

BACKGROUND: Rodent studies suggest that the peptide hormone insulin-like factor 3 (Insl3) made by the fetal testis is responsible for the first transabdominal phase of testicular descent, and may be affected by xenobiotics to disrupt male reproductive tract development. To date, there is very little information on the production of INSL3 by the human fetus during gestation. The objective of the present study was to determine the concentrations and time course during pregnancy of INSL3 and testosterone production in human fetuses and their associations with maternal characteristics, pregnancy complications and outcome. METHODS: This is a retrospective cohort study in which women who contributed amniotic fluid specimens to a bank from 2003-2006 were followed to determine their pregnancy complications and pregnancy outcome. Amniotic fluid specimens were collected from the Reproductive Genetics Laboratory of the Hospital of the University of Pennsylvania subsequent to routine amniocentesis. INSL3 and total testosterone levels were measured in amniotic fluid (from n = 50 female, n = 237 male fetuses) by validated immunoassays and correlated with maternal characteristics, pregnancy complications and outcomes. RESULTS: INSL3 was only detectable in amniotic fluid from male fetuses, and highest levels occurred from weeks 15-17 of gestation. INSL3 concentration was positively associated with increased birth weight, the occurrence of pre-eclampsia and advanced maternal age, but not with testosterone levels. CONCLUSIONS: INSL3 concentration in human amniotic fluid is potentially predictive of fetal sex and pre-eclampsia, and presumably reflects the functioning of the fetal Leydig cell population.     

Placental ischaemia is a consequence rather than a cause of pre-eclampsia

The aetiology or pre-eclampsia remains unknown, but it is widely accepted that the disorder is placental in origin. Failed trophoblast invasion of the maternal spiral arteries is accepted to be a central pathogenetic mechanism. However, the concept of failed trophoblast invasion is based on an assumption rather than direct scientific observation and there are other likely explanations for this phenomenon. The criteria for disease causation, such as the Bradford-Hill criteria are central to the ascertainment of causal relationships in modern medicine and these criteria are used here to assess the relationship between the placenta and pre-eclampsia. There is a strong association between pre-eclampsia and small (rather than large) placentas and an appropriate dose-response relationship does not exist. Failed trophoblast invasion of the spiral arteries is not specific to pre-eclampsia and occurs in other pregnancy complications and in up to 40% of biopsies from normal pregnancies and the relationship between placental ischaemia and pre-eclampsia is very inconsistent. A placental cause for pre-eclampsia is not consistent with the pathogenesis of other pregnancy complications like gestational diabetes mellitus. If pre-eclampsia was a disease of trophoblast origin, the risk of the disease should be determined by trophoblast rather than maternal factors. However, evidence from assisted reproduction shows that the risk of a woman developing pre-eclampsia is almost entirely dependent on maternal factors and independent of the embryo from which the placenta develops. There is currently no plausible proven mechanism by which the placenta causes pre-eclampsia. The syndrome typically gets worse, and can arise de-novo after the placenta has been removed, calling into question the role of the placenta in its causation. Uterine artery ligation in humans, unlike in animal experiments, is not associated with an increased incidence of pre-eclampsia, calling into question the role of poor utero-placental perfusion in the cause of the disease in humans. The signals that initiate maternal adaptive responses during pregnancy come from or through the placenta into the maternal milieu but as is the case with gestational diabetes mellitus, are not necessarily the cause of maternal disease. Pre-eclampsia causes renal, hepatic, myocardial, cerebral and adrenal ischaemia--that is ischaemia in all highly vascular organs. Placental ischaemia, like ischaemia in all other organs, is a consequence rather than a causal factor in the development of the syndrome and this has profound consequences for research strategies.     

Calreticulin in human pregnancy and pre-eclampsia

Pre-eclampsia is a disorder of human pregnancy that involves pregnancy-induced maternal hypertension and proteinuria. Evidence indicates that pre-eclampsia involves widespread activation of maternal endothelial cells. Calreticulin is a ubiquitously expressed, multi-functional protein that has been shown to have both pro- and anti-inflammatory effects on cultured endothelial cells in vitro and in whole animals. In order to clarify the role of this protein in normal human pregnancy and in pre-eclampsia, this study has measured expression of calreticulin in maternal blood and in placenta in patients with pre-eclampsia and in control pregnancies. There was a significant increase (approximately 5-fold) in calreticulin in plasma in term pregnant women compared with women who were not pregnant. There was no difference, however, in calreticulin in plasma from women who were sampled at first trimester, second trimester and at term. In addition, there was a significant increase (approximately 50%) in calreticulin in plasma from pre-eclamptic women compared to controls. Calreticulin mRNA and protein expression in placenta were not changed between pre-eclampsia and control pregnancies. These novel results indicate that calreticulin is increased in peripheral maternal blood early in pregnancy and remains elevated throughout normal gestation and that there is a further increase in calreticulin in pre-eclampsia.     

The genetics of pre‐eclampsia: a feto‐placental or maternal problem?

Pre-eclampsia is a potentially life-threatening disease of women during pregnancy leading to hypertension and proteinuria. It affects 1 in 15 pregnancies but, despite intense research efforts, the cause of the disease remains mysterious. Because pre-eclampsia only occurs during pregnancy and its symptoms resolve after delivery, factors from the placenta are thought to be involved. The role of the placenta could be production of 'abnormal' factors that initiate widespread inflammation and vaso-constriction. Alternatively, because the placenta normally contributes to maternal cardiovascular adaptations of pregnancy, it may be that normal placental functions fail in pre-eclampsia or that susceptibilities in the mother to hypertensive, vascular and/or renal disease prevent the appropriate normal responses to them. The potential contributions of both maternal and fetal genes to the onset of the disease have complicated the genetic analysis of the disease in humans. Recent studies have identified strains of transgenic and mutant mice that develop the hallmark features of pre-eclampsia-like disease - gestational hypertension, proteinuria and kidney lesions (glomerulosclerosis). Comparison of three different mouse models suggests that pre-eclampsia can be initiated by at least three independent mechanisms: pre-existing borderline maternal hypertension that is exacerbated by pregnancy (BPH/5 strain of mice), elevated levels of the vasoconstrictor angiotensin II in the maternal circulation by placental over-production of renin (renin/angiotensinogen transgenic mice), and placental pathology (p57Kip2 mutant mice). These findings imply that the pathogenesis of pre-eclampsia cannot be explained by a single mechanism. Therefore, segregation of the human disease into different subtypes may be a key first step in identifying genetic risk factors.     

Genetic association of the activin A receptor gene (ACVR2A) and pre-eclampsia

Pre-eclampsia is a common serious disorder of human pregnancy,which is associated with significant maternal and perinatalmorbidity and mortality. The suspected aetiology of pre-eclampsiais complex, with susceptibility being attributable to multipleenvironmental factors and a large genetic component. Recently,we reported significant linkage to chromosome 2q22 in 34 Australian/NewZealand (Aust/NZ) pre-eclampsia/eclampsia families, and activinA receptor type IIA (ACVR2A) was identified as a strong positionalcandidate gene at this locus. In an attempt to identify theputative risk variants, we have now comprehensively re-sequencedthe entire coding region of the ACVR2A gene and the conservednon-coding sequences in a subset of 16 individuals from thesefamilies. We identified 45 single nucleotide polymorphisms (SNPs),with 9 being novel. These SNPs were genotyped in our total familysample of 480 individuals from 74 Aust/NZ pre-eclampsia families(including the original 34 genome-scanned families). Our bestassociations between ACVR2A polymorphisms and pre-eclampsiawere for rs10497025 (P = 0.025), rs13430086 (P = 0.010) andthree novel SNPs: LF004, LF013 and LF020 (all with P = 0.018).After correction for multiple hypothesis testing, none of theseassociations reached significance (P > 0.05). Based on thesedata, it remains unclear what role, if any, ACVR2A polymorphismsplay in pre-eclampsia risk, at least in these Australian families.However, it would be premature to rule out this gene as significantassociations between ACVR2A SNPs and pre-eclampsia have recentlybeen reported in a large Norwegian (HUNT) population sample.     

A polymorphism in the MTHFD1 gene increases a mother's risk of having an unexplained second trimester pregnancy loss

Low maternal folate or vitamin B12 status has been implicated in numerous pregnancy complications including spontaneous abortion. The primary aim of this study was to test a polymorphism within the trifunctional folate enzyme MTHFD1 (5,10-methylenetetrahydrofolate dehydrogenase, 5,10-methenyltetrahydrofolate cyclohydrolase, 10-formyltetrahydrofolate synthetase) for an association with a mother's risk of having an unexplained second trimester pregnancy loss. We genotyped 125 women who had at least one unexplained spontaneous abortion or intrauterine fetal death between 13 and 26 weeks gestation and 625 control women with no history of prior pregnancy loss. Our study is the first to identify an association between the MTHFD1 1958G-->A (R653Q) polymorphism and the maternal risk of having an unexplained second trimester pregnancy loss. Women who are MTHFD1 1958AA homozygous have a 1.64-fold increased risk of having an unexplained second trimester loss compared to women who are MTHFD1 1958AG or 1958GG [OR 1.64 (1.05-2.57), P = 0.03]. It has been reported that polymorphisms in 5,10-methylenetetrahydrofolate reductase (MTHFR), 677C-->T (A222V), transcobalamin II (TCII), 776C-->G (P259R), are associated with pregnancy loss. Both variants were tested in this study. Neither showed evidence of significantly affecting the maternal risk of having a second trimester pregnancy loss. In conclusion, the MTHFD1 1958AA genotype may be an important maternal risk factor to consider during pregnancy.     

Identification of fetal mesenchymal stem cells in maternal blood: implications for non-invasive prenatal diagnosis

Strategies for genetic prenatal diagnosis on fetal cells in the maternal circulation have been limited by lack of a cell type present only in fetal blood. However, the recent identification of mesenchymal stem cells (MSC) in first trimester fetal blood offers the prospect of targeting MSC for non-invasive prenatal diagnosis. We developed protocols for fetal MSC enrichment from maternal blood and determined sensitivity and specificity in mixing experiments of male fetal MSC added to female blood, in dilutions from 1 in 10(5) to 10(8). We then used the optimal protocol to isolate fetal MSC from maternal blood in the first trimester, using blood taken after surgical termination of pregnancy as a model of increased feto-maternal haemorrhage. In model mixtures, we could amplify one male fetal MSC in 2.5 x 10(7) adult female nucleated cells, yielding a 100% pure population of fetal cells, but not one fetal MSC in 10(8) nucleated cells. Fetal MSC were identified in one of 20 post-termination maternal blood samples and confirmed as fetal MSC by XY fluorescence in-situ hybridization (FISH), immunophenotyping and osteogenic and adipogenic differentiation. We report the isolation of fetal MSC from maternal blood; however, their rarity in post-termination blood suggests they are unlikely to have a role in non-invasive prenatal diagnosis. Failure to locate these cells routinely may be attributed to their low frequency in maternal blood, to sensitivity limitations of enrichment technology, and/or to their engraftment in maternal tissues soon after transplacental passage. We speculate that gender microchimerism in post-reproductive maternal tissues might result from feto-maternal trafficking of MSC in early pregnancy.     

Fertilization and early embryology: A comparative prospective study using matched samples to determine the influence of subnormal hypo-osmotic test scores of spermatozoa on subsequent fertilization and pregnancy rates following in-vitro fertilization

The achievement of pregnancies in vivo is rare in couples wherethe male partner has defective sperm membranes as shown by hypo-osmoticswelling (HOS) test scores of <50%. However, there have beenmixed reports on the value of the HOS test in predicting outcomefollowing invitro fertilization; some studies suggest reducedfertilization rates and others find little, if any, predictabilityof decreased fertilization. The assumption has been made thatfertilization rates are proportional to pregnancy rates; however,this may not necessarily be true since defective spermatozoacould lead to a less viable pre-embryo and therefore a decreasedviable pregnancy rate. We performed a comparative prospectivestudy using matched controls to evaluate fertilization ratesand to determine subsequent pregnancy rates. The mean HOS scoreswere 70.0 and 36.7% respectively, with mean motile sperm concentrationsof 35.7 and 34.0 x 10⁶/ml in 27 matched pairs. There was nodifference in the mean number of oocytes retrieved, fertilizationrates or number of embryos transferred between the two groupsby HOS score. The clinical and viable pregnancy rates and implantationrates were 25.9, 18.5 and 9.9% for normal versus 3.7, 3.7 and1.1% for subnormal groups. These data suggest that low HOS scoresmay be associated with the formation of defective embryos, leadingto low pregnancy rates but normal fertilization rates.     

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.