Philip N. Baker

Placental apoptosis in normal human pregnancy

OBJECTIVES The study aims were to conclusively demonstrate apoptosis in the human placenta and to quantify its incidence at different stages of pregnancy. STUDY DESIGN Placental samples were obtained from 28 first-trimester pregnancies and 38 uncomplicated third-trimester pregnancies. Light microscopy, electron microscopy, and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate marker nick end-labeling staining were used to identify apoptosis. Light microscopy was used to quantify its incidence. RESULTS Apoptosis has been conclusively demonstrated within placental tissue. Quantification of apoptosis (medians and interquartile ranges) was as follows: first trimester (n = 28), 0.07% of cells (0.05% to 0.14%); third trimester (n = 39), 0.14% of cells (0.09% to 0.20%). The incidence of apoptosis was significantly higher in the third trimester than in the first trimester (p < 0.01, Mann-Whitney U test). CONCLUSIONS Placental apoptosis increases significantly as pregnancy progresses, suggesting that it may play a role in the normal development and aging of the placenta.

Higher risk of offspring schizophrenia following antenatal maternal exposure to severe adverse life events.

CONTEXT Most societies believe that a mothers psychological state can influence her unborn baby. Severe adverse life events during pregnancy have been consistently associated with an elevated risk of low birth weight and prematurity. Such events during the first trimester have also been associated with risk of congenital malformations. OBJECTIVE To assess the effect in offspring of antenatal maternal exposure to an objective measure of stress on risk of adverse neurodevelopment, specifically schizophrenia. We hypothesized that the strongest relationship would be to maternal exposures during the first trimester. DESIGN Population-based study. SETTING Denmark. PARTICIPANTS In a cohort of 1.38 million Danish births from 1973 to 1995, mothers were considered exposed if 1 (or more) of their close relatives died or was diagnosed with cancer, acute myocardial infarction, or stroke syndrome up to 6 months before conception or during pregnancy. Offspring were followed up from their 10th birthday until their death, migration, onset of schizophrenia, or June 30, 2005; admissions were identified by linkage to the Central Psychiatric Register. Main Outcome Measure Schizophrenia. RESULTS The risk of schizophrenia and related disorders was raised in offspring whose mothers were exposed to death of a relative during the first trimester (adjusted relative risk, 1.67 [95% confidence interval, 1.02-2.73]). Death of a relative during other trimesters or up to 6 months before pregnancy were not linked with a higher risk of schizophrenia. CONCLUSIONS Our population-based study suggests that severe stress to a mother during the first trimester may alter the risk of schizophrenia in offspring. This finding is consistent with ecological evidence from whole populations exposed to severe stressors and suggests that environment may influence neurodevelopment at the feto-placental-maternal interface.

Increased placental apoptosis in intrauterine growth restriction

OBJECTIVES Our purpose was to investigate a possible role for apoptosis in the pathophysiologic mechanisms of intrauterine growth restriction. STUDY DESIGN Placental samples were obtained from 43 uncomplicated third-trimester pregnancies and from 26 pregnancies complicated by intrauterine growth restriction. The definition used to identify cases of intrauterine growth restriction depended on three criteria: clinical evidence of suboptimal growth, ultrasonographic evidence of deviation from an appropriate growth percentile, and individualized birth weight ratios <10th percentile. Light microscopy was used to quantify the incidence of apoptosis. Electron microscopy and TUNEL (terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling) staining were used to confirm the occurrence of apoptosis. RESULTS Quantification of apoptosis (medians and interquartile ranges) resulted in the following values: normal third trimester (n = 43) 0.14% of cells (0.08% to 0.20%) and intrauterine growth restriction third trimester (n = 26) 0.24% of cells (0.16% to 0.29%). The incidence of apoptosis was significantly higher in placentas from pregnancies with intrauterine growth restriction compared with normal third-trimester placentas (p < 0.01, Mann Whitney U test). CONCLUSIONS These results suggest that apoptosis may play a role in the pathophysiologic mechanisms of intrauterine growth restriction.

Clinical risk prediction for pre-eclampsia in nulliparous women: development of model in international prospective cohort

Objectives To develop a predictive model for pre-eclampsia based on clinical risk factors for nulliparous women and to identify a subgroup at increased risk, in whom specialist referral might be indicated. Design Prospective multicentre cohort. Setting Five centres in Auckland, New Zealand; Adelaide, Australia; Manchester and London, United Kingdom; and Cork, Republic of Ireland. Participants 3572 “healthy” nulliparous women with a singleton pregnancy from a large international study; data on pregnancy outcome were available for 3529 (99%). Main outcome measure Pre-eclampsia defined as ≥140 mm Hg or diastolic blood pressure ≥90 mm Hg, or both, on at least two occasions four hours apart after 20 weeks’ gestation but before the onset of labour, or postpartum, with either proteinuria or any multisystem complication. Preterm pre-eclampsia was defined as women with pre-eclampsia delivered before 37+0 weeks’ gestation. In the stepwise logistic regression the comparison group was women without pre-eclampsia. Results Of the 3529 women, 186 (5.3%) developed pre-eclampsia, including 47 (1.3%) with preterm pre-eclampsia. Clinical risk factors at 14-16 weeks’ gestation were age, mean arterial blood pressure, body mass index (BMI), family history of pre-eclampsia, family history of coronary heart disease, maternal birth weight, and vaginal bleeding for at least five days. Factors associated with reduced risk were a previous single miscarriage with the same partner, taking at least 12 months to conceive, high intake of fruit, cigarette smoking, and alcohol use in the first trimester. The area under the receiver operating characteristics curve (AUC), under internal validation, was 0.71. Addition of uterine artery Doppler indices did not improve performance (internal validation AUC 0.71). A framework for specialist referral was developed based on a probability of pre-eclampsia generated by the model of at least 15% or an abnormal uterine artery Doppler waveform in a subset of women with single risk factors. Nine per cent of nulliparous women would be referred for a specialist opinion, of whom 21% would develop pre-eclampsia. The relative risk for developing pre-eclampsia and preterm pre-eclampsia in women referred to a specialist compared with standard care was 5.5 and 12.2, respectively. Conclusions The ability to predict pre-eclampsia in healthy nulliparous women using clinical phenotype is modest and requires external validation in other populations. If validated, it could provide a personalised clinical risk profile for nulliparous women to which biomarkers could be added. Trial registration ACTRN12607000551493.

Uterine natural killer cells initiate spiral artery remodeling in human pregnancy

Uterine spiral artery remodeling is required for successful human pregnancy; impaired remodeling is associated with pregnancy complications, including late miscarriage, preeclampsia, and fetal growth restriction. The molecular triggers of remodeling are not known, but it is now clear that there are “trophoblast‐independent” and “trophoblast‐dependent” stages. Uterine natural killer (uNK) cells are abundant in decidualized endometrium in early pregnancy; they surround spiral arteries and secrete a range of angiogenic growth factors. We hypothesized that uNK cells mediate the initial stages of spiral artery remodeling. uNK cells and extravillous trophoblast (EVT) cells were isolated from early pregnancy decidua and placenta. Chorionic plate arteries from full‐term placentas and spiral arteries from nonpregnant myometrium were cultured with angiogenic growth factors or conditioned medium (CM) from uNK cells or EVT or uNK cell/EVT cocultures. In both vessel models, uNK cell CM induced disruption of vascular smooth muscle cells (VSMCs) and breakdown of extracellular matrix components. Angiopoietin (Ang)‐1, Ang‐2, interferon‐γ, and VEGF‐C also disrupted VSMC integrity with an Ang‐2 inhibitor abrogating the effect of uNK cell CM. These results provide compelling evidence that uNK cells contribute to the early stages of spiral artery remodeling; failure of this process could contribute to pregnancy pathology.—Robson, A., Harris, L. K., Innes, B. A., Lash, G. E., Aljunaidy, M. M., Aplin, J. D., Baker, P. N., Robson, S. C., Bulmer, J. N. Uterine natural killer cells initiate spiral artery remodeling in human pregnancy. FASEB J. 26, 4876–4885 (2012). www.fasebj.org

A prospective study of micronutrient status in adolescent pregnancy

BACKGROUND Adolescents are more likely than adults to consume energy-dense, micronutrient-poor diets and to experience adverse pregnancy outcomes. OBJECTIVES The objectives were to assess micronutrient intake and blood biomarkers prospectively in pregnant adolescents recruited to the About Teenage Eating (ATE) Study and to determine associations with pregnancy outcome. DESIGN Pregnant adolescents (n = 500) were recruited from 2 UK inner city populations. Dietary intake was assessed with three 24-h dietary recalls, and micronutrient status was assessed by measurement of third trimester blood biomarkers. Pregnancy outcomes included small-for-gestational age (SGA) birth and preterm delivery. RESULTS Median iron and folate intakes were lower than UK and US recommended amounts. Folate and vitamin B-12 status were lower in smokers, despite no differences in dietary intake. Serum folate was <7.0 nmol/L in 12% of subjects, and serum total homocysteine (tHcy) was elevated (>10 micromol/L) in 20% of subjects. Fifty-two percent of the subjects had iron deficiency anemia, and 30% had serum 25-hydroxyvitamin D concentrations <25 nmol/L. The incidence of SGA birth was higher in subjects with poorer folate status (red blood cell folate, P = 0.003; serum folate, P = 0.02; tHcy, P = 0.01; simple regression) and those with low folate intakes, regardless of the inclusion (P = 0.021) or exclusion (P = 0.049) of intake from supplements (simple regression). Adjustment for confounding variables confirmed the independence of these associations. The risk of SGA birth was also higher in subjects with low food iron intake (P = 0.049), but not when intake included iron from supplements (P = 0.21). The risk of SGA birth was lower in subjects with iron deficiency anemia (P = 0.002). CONCLUSION Poor micronutrient intake and status increase the risk of SGA births in pregnant adolescents.

Uterine Spiral Artery Remodeling Involves Endothelial Apoptosis Induced by Extravillous Trophoblasts Through Fas/FasL Interactions

Objective— Invasion of uterine spiral arteries by extravillous trophoblasts in the first trimester of pregnancy results in loss of endothelial and musculoelastic layers. This remodeling is crucial for an adequate blood supply to the fetus with a failure to remodel implicated in the etiology of the hypertensive disorder preeclampsia. The mechanism by which trophoblasts induce this key process is unknown. This study gives the first insights into the potential mechanisms involved. Methods and Results— Spiral arteries were dissected from nonplacental bed biopsies obtained at Caesarean section, and a novel model was used to mimic in vivo events. Arteries were cultured with trophoblasts in the lumen, and apoptotic changes in the endothelial layer were detected after 20 hours, leading to loss of endothelium by 96 hours. In vitro, coculture experiments showed that trophoblasts stimulated apoptosis of primary decidual endothelial cells and an endothelial cell line. This was blocked by caspase inhibition and NOK2, a FasL blocking antibody. NOK2 also abrogated trophoblast-induced endothelial apoptosis in the vessel model. Conclusions— Extravillous trophoblast induction of endothelial apoptosis is a possible mechanism by which the endothelium is removed, and vascular remodeling may occur in uterine spiral arteries. Fas/FasL interactions have an important role in trophoblast-induced endothelial apoptosis.

Insulin-like growth factor I and II regulate the life cycle of trophoblast in the developing human placenta

The main disorders of human pregnancy are rooted in defective placentation. Normal placental development depends on proliferation, differentiation, and fusion of cytotrophoblasts to form and maintain an overlying syncytiotrophoblast. There is indirect evidence that the insulin-like growth factors (IGFs), which are aberrant in pregnancy disorders, are involved in regulating trophoblast turnover, but the processes that control human placental growth are poorly understood. Using an explant model of human first-trimester placental villus in which the spatial and ontological relationships between cell populations are maintained, we demonstrate that cytotrophoblast proliferation is enhanced by IGF-I/IGF-II and that both factors can rescue cytotrophoblast from apoptosis. Baseline cytotrophoblast proliferation ceases in the absence of syncytiotrophoblast, although denuded cytotrophoblasts can proliferate when exposed to IGF and the rate of cytotrophoblast differentiation/fusion and, consequently, syncytial regeneration, increases. Use of signaling inhibitors suggests that IGFs mediate their effect on cytotrophoblast proliferation/syncytial formation through the MAPK pathway, whereas effects on survival are regulated by the phosphoinositide 3-kinase pathway. These results show that directional contact between cytotrophoblast and syncytium is important in regulating the relative amounts of the two cell populations. However, IGFs can exert an exogenous regulatory influence on placental growth/development, suggesting that manipulation of the placental IGF axis may offer a potential therapeutic route to the correction of inadequate placental growth.

Fetal weight estimation by echo-planar magnetic resonance imaging.

Fetal weight was estimated in utero in eleven singleton pregnancies by measurement of fetal volume with echo-planar imaging (EPI), a form of magnetic resonance imaging, and by ultrasound measurements. EPI estimates of fetal volume were closely correlated with actual birthweight (R = 0.97). The median difference (expressed as a percentage of actual birthweight) between actual and EPI-estimated birthweights was 3.0% (range 0.6-9.9); this discrepancy was significantly smaller than that found for ultrasonographic estimates (6.5% [1.7-17.8]; p < 0.01).

Early pregnancy prediction of preeclampsia in nulliparous women, combining clinical risk and biomarkers: the Screening for Pregnancy Endpoints (SCOPE) international cohort study

More than half of all cases of preeclampsia occur in healthy first-time pregnant women. Our aim was to develop a method to predict those at risk by combining clinical factors and measurements of biomarkers in women recruited to the Screening for Pregnancy Endpoints (SCOPE) study of low-risk nulliparous women. Forty-seven biomarkers identified on the basis of (1) association with preeclampsia, (2) a biological role in placentation, or (3) a role in cellular mechanisms involved in the pathogenesis of preeclampsia were measured in plasma sampled at 14 to 16 weeks’ gestation from 5623 women. The cohort was randomly divided into training (n=3747) and validation (n=1876) cohorts. Preeclampsia developed in 278 (4.9%) women, of whom 28 (0.5%) developed early-onset preeclampsia. The final model for the prediction of preeclampsia included placental growth factor, mean arterial pressure, and body mass index at 14 to 16 weeks’ gestation, the consumption of ≥3 pieces of fruit per day, and mean uterine artery resistance index. The area under the receiver operator curve (95% confidence interval) for this model in training and validation cohorts was 0.73 (0.70–0.77) and 0.68 (0.63–0.74), respectively. A predictive model of early-onset preeclampsia included angiogenin/placental growth factor as a ratio, mean arterial pressure, any pregnancy loss <10 weeks, and mean uterine artery resistance index (area under the receiver operator curve [95% confidence interval] in training and validation cohorts, 0.89 [0.78–1.0] and 0.78 [0.58–0.99], respectively). Neither model included pregnancy-associated plasma protein A, previously reported to predict preeclampsia in populations of mixed parity and risk. In nulliparous women, combining multiple biomarkers and clinical data provided modest prediction of preeclampsia. # Novelty and Significance {#article-title-41}More than half of all cases of preeclampsia occur in healthy first-time pregnant women. Our aim was to develop a method to predict those at risk by combining clinical factors and measurements of biomarkers in women recruited to the Screening for Pregnancy Endpoints (SCOPE) study of low-risk nulliparous women. Forty-seven biomarkers identified on the basis of (1) association with preeclampsia, (2) a biological role in placentation, or (3) a role in cellular mechanisms involved in the pathogenesis of preeclampsia were measured in plasma sampled at 14 to 16 weeks’ gestation from 5623 women. The cohort was randomly divided into training (n=3747) and validation (n=1876) cohorts. Preeclampsia developed in 278 (4.9%) women, of whom 28 (0.5%) developed early-onset preeclampsia. The final model for the prediction of preeclampsia included placental growth factor, mean arterial pressure, and body mass index at 14 to 16 weeks’ gestation, the consumption of ≥3 pieces of fruit per day, and mean uterine artery resistance index. The area under the receiver operator curve (95% confidence interval) for this model in training and validation cohorts was 0.73 (0.70–0.77) and 0.68 (0.63–0.74), respectively. A predictive model of early-onset preeclampsia included angiogenin/placental growth factor as a ratio, mean arterial pressure, any pregnancy loss <10 weeks, and mean uterine artery resistance index (area under the receiver operator curve [95% confidence interval] in training and validation cohorts, 0.89 [0.78–1.0] and 0.78 [0.58–0.99], respectively). Neither model included pregnancy-associated plasma protein A, previously reported to predict preeclampsia in populations of mixed parity and risk. In nulliparous women, combining multiple biomarkers and clinical data provided modest prediction of preeclampsia.