Uteroplacental vasculature

Spiral, uterine artery doppler and placental ultrasound in relation to preeclampsia

Preeclampsia (PE) is a multiorgan disorder that complicates around 2-8% of pregnancies and is a major cause of perinatal and maternal morbidity and mortality. PE is a clinical syndrome characterized by hypertension secondary to systemic inflammation, endothelial dysfunction, and syncytiotrophoblast stress leading to hypertension and multiorgan dysfunction. The uterine arteries are the main blood vessels that supply blood to the uterus. They give off branches and plays an important role in maintaining blood supply during pregnancy. The arcuate artery originates from the uterine artery and runs medially through the myometrium. The arcuate arteries divide almost directly into anterior and posterior branches, from which the radial artery leads directly to the uterine cavity during their course. Near the endometrium-myometrium junction, the radial artery generates spiral arteries within the basal layer and functional endometrium. The walls of radial and spiral arteries are rich in smooth muscle, which is lost when trophoblast cells invade and become large-caliber vessels. This physiological transformation of uteroplacental spiral arteries is critical for successful placental implantation and normal placental function. In normal pregnancy, the luminal diameter of the spiral arteries is greatly increased, and the vascular smooth muscle is replaced by trophoblast cells. This process and changes in the spiral arteries are called spiral artery remodeling. In PE, this genetically and immunologically governed process is deficient and therefore there is decreased vascular capacitance and increased resistance in the uteroplacental circulation. Furthermore, this defect in uteroplacental spiral artery remodeling is not only associated with early onset PE, but also with fetal growth restriction, placental abruption, and spontaneous premature rupture of membranes. Doppler ultrasound allows non-invasive assessment of placentation, while the flow impedance decreases as the pregnancy progresses in normal pregnancies, in those destined to develop preeclampsia the impedance is increased.

Fetal-placental MR angiography at 1.5 T and 3 T

OBJECTIVES

The objective of this work was to investigate the application of 2D Time-of-Flight (TOF) magnetic resonance angiography (MRA) to observe the placental vasculature at both 1.5 T and 3 T.

METHODS

Fifteen appropriate for gestational age (AGA) (GA: 29.7 ± 3.4 weeks; GA range: 23 and 6/7 weeks to 36 and 2/7 weeks) and eleven patients with an abnormal singleton pregnancy (GA: 31.4 ± 4.4 weeks; GA range: 24 weeks to 35 and 2/7 weeks) were recruited in the study. Three AGA patients were scanned twice at different gestational ages. Patients were scanned either at 3 T or 1.5 T using both T2-HASTE and 2D TOF to image the entire placental vasculature.

RESULTS

The umbilical, chorionic vessels, stem vessels, arcuate arteries, radial arteries, and spiral arteries were shown in most of the subjects. Hyrtl's anastomosis was found in two subjects in the 1.5 T data. The uterine arteries were observed in more than half of the subjects. For those patients scanned twice, the same spiral arteries were identified in both scans.

CONCLUSIONS

2D TOF is a technique that can be applied in studying the fetal-placental vasculature at both 1.5 T and 3 T.

A mathematical model of maternal vascular growth and remodeling and changes in maternal hemodynamics in uncomplicated pregnancy

The maternal vasculature undergoes tremendous growth and remodeling (G&R) that enables a > 15-fold increase in blood flow through the uterine vasculature from conception to term. Hemodynamic metrics (e.g., uterine artery pulsatility index, UA-PI) are useful for the prognosis of pregnancy complications; however, improved characterization of the maternal hemodynamics is necessary to improve prognosis. The goal of this paper is to develop a mathematical framework to characterize maternal vascular G&R and hemodynamics in uncomplicated human pregnancies. A validated 1D model of the human vascular tree from the literature was adapted and inlet blood flow waveforms at the ascending aorta at 4 week increments from 0 to 40 weeks of gestation were prescribed. Peripheral resistances of each terminal vessel were adjusted to achieve target flow rates and mean arterial pressure at each gestational age. Vessel growth was governed by wall shear stress (and axial lengthening in uterine vessels), and changes in vessel distensibility were related to vessel growth. Uterine artery velocity waveforms generated from this model closely resembled ultrasound results from the literature. The literature UA-PI values changed significantly across gestation, increasing in the first month of gestation, then dramatically decreasing from 4 to 20 weeks. Our results captured well the time-course of vessel geometry, material properties, and UA-PI. This 1D fluid-G&R model captured the salient hemodynamic features across a broad range of clinical reports and across gestation for uncomplicated human pregnancy. While results capture available data well, this study highlights significant gaps in available data required to better understand vascular remodeling in pregnancy.

Targeting the Dysfunctional Placenta to Improve Pregnancy Outcomes Based on Lessons Learned in Cancer

In recent decades, our understanding of the disrupted mechanisms that contribute to major obstetrical diseases, including preeclampsia, fetal growth restriction, preterm birth, and gestational diabetes, has increased exponentially. Common to many of these obstetric diseases is placental maldevelopment and dysfunction; the placenta is a significant component of the maternal-fetal interface involved in coordinating, facilitating, and regulating maternal and fetal nutrient, oxygen and waste exchange, and hormone and cytokine production. Despite the advances in our understanding of placental development and function, there are currently no treatments for placental maldevelopment and dysfunction. However, given the transient nature and accessibility from the maternal circulation, the placenta offers a unique opportunity to develop targeted therapeutics for routine obstetric practices. Furthermore, given the similar developmental paradigms between the placenta and cancer, there is an opportunity to appropriate current knowledge from advances in targeted therapeutics in cancer treatments. In this review, we highlight the similarities between early placental development and cancer and introduce a number of targeted therapies currently being explored in cancer and pregnancy. We also propose a number of new effectors currently being targeted in cancer research that have the potential to be targeted in the development of treatments for pregnancy complications. Finally, we describe a method for targeting the placenta using nonviral polymers that are capable of delivering plasmids, small interfering RNA, and other effector nucleic acids, which could ultimately improve fetal and maternal outcomes from complicated pregnancies.

Placental bed research: I. The placental bed: from spiral arteries remodeling to the great obstetrical syndromes

The term placental bed was coined to describe the maternal-fetal interface (ie, the area in which the placenta attaches itself to the uterus). Appropriate vascularization of this area is of vital importance for the development of the fetus; this is why systematic investigations of this area have now been carried out. Initially, the challenge was the identification and classification of the various successive branching of uterine arteries in this area. These vessels have a unique importance because failure of their physiological transformation is considered to be the anatomical basis for reduced perfusion to the intervillous space in women with preeclampsia, fetal growth restriction, preterm labor, preterm premature rupture of membranes, abruptio placentae, and fetal death. To investigate in depth the pathophysiology of the placental bed, some 60 years ago, a large number of placental bed biopsies, as well as of cesarean hysterectomy specimens with placenta in situ, from both early and late normotensive and hypertensive pregnancies, were carefully dissected and analyzed. Thanks to the presence of a series of specific physiological changes, characterized by the invasion and substitution of the arterial intima by trophoblast, this material allowed the identification in the placental bed of normal pregnancies of the main vessels, the uteroplacental arteries. It was then discovered that preeclampsia is associated with defective or absent transformation of the myometrial segment of the uteroplacental arteries. In addition, in severe hypertensive disease, atherosclerotic lesions were also found in the defective myometrial segment. Finally, in the basal decidua, a unique vascular lesion, coined acute atherosis, was also identified This disorder of deep placentation, coined defective deep placentation, has been associated with the great obstetrical syndromes, grouping together preeclampsia, intrauterine growth restriction, preterm labor, preterm premature rupture of membranes, late spontaneous abortion, and abruptio placentae. More recently, simplified techniques of tissue sampling have been also introduced: decidual suction allows to obtain a large number of decidual arteries, although their origin in the placental bed cannot be determined. Biopsies parallel to the surface of the basal plate have been more interesting, making possible to identify the vessels' region (central, paracentral, or peripheral) of origin in the placental bed and providing decidual material for immunohistochemical studies. Finally, histochemical and electron microscopy investigations have now clarified the pathology and pathogenetic mechanisms underlying the impairment of the physiological vascular changes.

Placenta Increta Presenting as Exaggerated Placental Site Reaction

Exaggerated placental site (EPS) is usually an incidental finding seen in curettings after an abortion. Placenta increta is, by definition, a disease that damages and destroys myometrium; however, prior literature has not paid sufficient attention to the role of myometrium in its pathogenesis and diagnosis. We present an unusual case of placenta increta in a hysterectomy performed for uterine perforation after curettage for the termination of pregnancy at 18 weeks. The initial histologic section of the implantation site suggested EPS. Actin stains showed degenerated inflamed muscle at the EPS-like site, keratin stains showed interstitial trophoblast in the zone of myometrial damage, and the wall of the corpus was grossly thinned under the placenta. The myometrial damage may have softened the wall, predisposing to uterine perforation by the curettage procedure.

Placenta Accreta and Placenta Increta: An Approach to Pathogenesis Based on the Trophoblastic Differentiation Pathway

Morbid adherence remains a puzzling disease. This paper suggests that normal and morbidly adherent placentation may be viewed best in terms of trophoblastic stem cells and the mutually exclusive branches of the trophoblastic differentiation pathway-villous trophoblast (VT), interstitial and endovascular nonvillous trophoblast (NVT) at the implantation site, and a positional variation in the chorion. Based on cases of hysterectomies for morbid adherence seen over 30 years at a community hospital, analyzed with routine keratin stains, with actin and trichrome stains as indicated, and with attempts at ultrasonography-pathology correlation, we present selected observations. In true accreta, the site of morbid adherence was to dilated basal plate vessels infiltrated by endovascular NVT, with scant interstitial NVT, and normal myometrium. It appeared that excess blood flow into the placenta was due to excessively deep keratin-positive endovascular NVT that spread-independently of interstitial NVT-in an angiocentric fashion in both accreta and increta. Retroplacental abnormalities were due to myometrial destruction by interstitial NVT in increta, sometimes requiring actin stains for detection; and to an admixture of markedly dilated endometrial glands and vessels in true accreta, best appreciated with keratin stains. Variations of depth and extent in increta may be due to variations in myometrial tone, and in the protease-antiprotease balance. Morbidly adherent fetal membranes are described, and the role of caesarean section scars in incretas is addressed.

Uterine microvascular sensitivity to nanomaterial inhalation: An in vivo assessment

With the tremendous number and diverse applications of engineered nanomaterials incorporated in daily human activity, exposure can no longer be solely confined to occupational exposures of healthy male models. Cardiovascular and endothelial cell dysfunction have been established using in vitro and in situ preparations, but the translation to intact in vivo models is limited. Intravital microscopy has been used extensively to understand microvascular physiology while maintaining in vivo neurogenic, humoral, and myogenic control. However, a tissue specific model to assess the influences of nanomaterial exposure on female reproductive health has not been fully elucidated. Female Sprague Dawley (SD) rats were exposed to nano-TiO2 aerosols (171 ± 6 nm, 10.1 ± 0.39 mg/m(3), 5h) 24-hours prior to experimentation, leading to a calculated deposition of 42.0 ± 1.65 μg. After verifying estrus status, vital signs were monitored and the right horn of the uterus was exteriorized, gently secured over an optical pedestal, and enclosed in a warmed tissue bath using intravital microscopy techniques. After equilibration, significantly higher leukocyte-endothelium interactions were recorded in the exposed group. Arteriolar responsiveness was assessed using ionophoretically applied agents: muscarinic agonist acetylcholine (0.025 M; ACh; 20, 40, 100, and 200 nA), and nitric oxide donor sodium nitroprusside (0.05 M; SNP; 20, 40, and 100 nA), or adrenergic agonist phenylephrine (0.05 M; PE; 20, 40, and 100 nA) using glass micropipettes. Passive diameter was established by tissue superfusion with 10(-4)M adenosine. Similar to male counterparts, female SD rats present systemic microvascular dysfunction; however the ramifications associated with female health and reproduction have yet to be elucidated.

Oxygen as modulator of trophoblast invasion

At the time of blastocyst implantation the uterine spiral arteries have already undergone morphological changes in the absence of any extravillous trophoblast invasion. Only 2 weeks after implantation, extravillous trophoblast cells develop and come into first contact with decidual tissues. Invading through the decidual interstitium, extravillous trophoblasts potentially reach and transform spiral arteries into uteroplacental arteries. Spiral arterial erosion starts at about mid-first trimester, whereas flow of maternal blood into the intervillous space is continuously established only at the beginning of the second trimester. One key regulator of the number of extravillous trophoblasts is oxygen. The steep gradient in oxygen concentration within the first trimester placenta is diminished with the onset of maternal blood flow. This gradient is used by the trophoblast to generate a large number of invasive cells to adapt the arterial vasculature in the placental bed to the growing needs of the fetus. Changes in oxygen concentrations or other factors leading to alterations in the rates of proliferation and/or apoptosis of extravillous trophoblast clearly impact on the remodelling of the vessels. The respective consequences of a failure in trophoblast invasion are growth restrictions of the baby and perhaps other pregnancy complications.

The feto-maternal interface: setting the stage for potential immune interactions

Human implantation and placentation comprise the direct contact of fetal with maternal tissues culminating in the erosion of maternal tissues by fetal cells. A complex interplay of maternal and fetal factors is key to maintain pregnancy until delivery. Immunological interactions can be found at different stages, such as blastocyst attachment, trophoblast invasion into maternal tissues, and flow of maternal blood through the placenta. These interactions need tightly controlled mechanisms to avoid rejection of the conceptus. In this study, these sites of interaction are introduced on a morphological level to help immunologists create their hypotheses on how the immunological interactions may work.

Microvessel density in the placental bed among preeclampsia patients

CONTEXT AND OBJECTIVE

Morphological changes in the spiral arteries of the placental bed have been studied in patients with preeclampsia, one of the largest causes of maternal and perinatal morbidity and mortality. The reports show that vasospasm and vascular endothelial injury were two major pathological conditions for preeclampsia. The aim of this study was to investigate the microvessel density of spiral arteries in the placental bed, in pregnancies complicated by hypertension and proteinuria, and in normal pregnancies.

DESIGN AND SETTING

This was a cross-sectional survey of immunohistochemical studies on biopsies from the spiral arteries of the placental bed, among women undergoing cesarean sections for clinical and obstetrical reasons at Universidade Federal de São Paulo, São Paulo, Brazil.

METHODS

Placental bed biopsies were obtained during cesarean section after placenta removal, with direct viewing of the central area of placenta insertion. The microvessel density of spiral arteries was measured by immunohistochemical methods in decidual and myometrial segments, using CD34 antibody.

RESULTS

Biopsies containing spiral arteries were obtained from 34 hypertensive pregnant women with proteinuria, and 26 normotensive pregnant women. The microvessel densities in decidual and myometrial segments of the placental bed were compared between the groups. It was observed that, with increasing blood pressure and proteinuria, the microvessel density gradually decreased.

CONCLUSION

The presence of high levels of hypertension and proteinuria may be associated with a progressive decrease in microvessel density in the placental bed.

Vascular biology in implantation and placentation

Pregnancy leads to dramatic changes of the vascular system of the mother and enables the development of a completely new vascular system within the growing embryo including the formation of the placenta as the exchange organ between both circulations. Besides a general adaptation of the maternal blood system, the uterine spiral arteries display the greatest changes. Within placental villi angiogenesis as well as vasculogenesis can be found already a few weeks after implantation. Both systems in parallel will determine the blood flow within the placental villi and the intervillous space. Finally, compromised blood flow on either side of the placental membrane will not only lead to fetal malnutrition, but will also trigger morphological changes of the villous trees. This review tries to cover all the above-mentioned topics and will try to depict the consequences of poor placentation on mother and fetus.

Delayed normalization of uterine artery Doppler waveforms is not a benign phenomenon

OBJECTIVE

To evaluate the pregnancy outcome in patients with abnormal uterine artery Doppler flow velocity waveforms (FVW's) at 19-21 weeks, which were subsequently normal by 24-26 weeks, and to study the effect of low-dose aspirin on these waveforms.

DESIGN

The study group consisted of 49 patients who had abnormal uterine artery flow velocity waveforms (FVW's) at 19-21 weeks. These women were initially commenced on 100 mg slow-release aspirin at 20 weeks, which was discontinued at the follow-up visit, after confirming normal uterine artery Doppler FVW. The control group consisted of 730 patients with normal uterine artery Doppler waveforms at 19-21 weeks. The main outcome measures were: small for gestational age (SGA) <10th centile, pre-eclampsia, placental abruption, and perinatal mortality rate (PMR).

RESULTS

When compared with the control group, the study group had an increased risk of placental abruption (2% versus 0.27%, P = 0.05) 95% Confidence Intervals CI = 0.01-0.13), low birth weight (3087 versus 3383 gm, P = 0.0003), SGA <10th centile (32.7% versus 11.9%, P </= 0.0001 , CI = 0.14 -0.5), and PMR (2/49 versus 1/730, P < 0.0001 , CI = 0.003-0.37).

CONCLUSIONS

These findings suggest that delayed normalisation of the uterine artery Doppler waveform is not a benign phenomenon. This subgroup of patients is at increased risk of pregnancy complications, in particular SGA and placental abruption. These patients could benefit from serial ultrasound scans in the third trimester to evaluate fetal growth and well-being. Aspirin does not appear to play a major part in modifying uterine artery blood flow.

Insulin-like growth factor-binding protein 1 and insulin-like growth factor-binding protein 3 in pre-eclampsia

OBJECTIVE

To investigate circulating levels of insulin-like growth factor-binding protein 1 (IGFBP-1) and IGFBP-3 in the mother and the fetus in pregnancies complicated by pre-eclampsia, and the relationship between serum levels of IGFBPs and fetal birthweight.

DESIGN

A prospective study over an 18 month period.

SETTING

A tertiary care academic medical centre.

PARTICIPANTS

Sixty-six pregnant women with pre-eclampsia (35 cases of mild/moderate pre-eclampsia and 31 cases of severe pre-eclampsia) and 78 nonpre-eclamptic pregnant women of matched gestational weeks and maternal ages.

MAIN OUTCOME MEASURES

Serum concentrations of IGFBP-1 and IGFBP-3 at the time of delivery.

RESULTS

In pre-eclampsia associated with intrauterine growth retardation (IUGR), maternal and cord serum IGFBP-1 levels at the time of delivery were elevated. By contrast, circulating IGFBP-3 levels in both the mother and the fetus were lower in pre-eclampsia with IUGR than in nonpre-eclamptic pregnancy. However, there was no difference in serum IGFBP-1 and IGFBP-3 levels between pre-eclampsia without IUGR and nonpre-eclamptic pregnancy in both the mother and the fetus.

CONCLUSIONS

In pre-eclampsia, elevated concentrations of circulating IGFBP-1 and decreased serum IGFBP-3 levels were observed in both the mother and the fetus. However, these changes may simply reflect low birthweight in pre-eclampsia.

Pulmonary artery rupture in pregnancy complicating patent ductus arteriosus

Fatal haemopericardium in a 27 year old pregnant woman was caused by rupture of a dissecting aneurysm of the pulmonary artery. She had an uncorrected patent ductus arteriosus and severe pulmonary hypertension. The wall of the pulmonary artery showed atherosclerosis and cystic medionecrosis.

The prevention of the maternal manifestations of pre-eclampsia by intensive antihypertensive treatment

The purpose of the study was to determine if reduction of pregnancy hypertension to normal prevented the clinical maternal manifestations of pre-eclampsia. Thirty-six women with hypertension, but without proteinuria, were allotted at random to a test group of 17 who received intensive treatment, and a control group of 19 who were managed according to routine methods by hospital staff unconnected with the study. The development of proteinuria was chosen as an indicator of pre-eclampsia. Proteinuria developed significantly more often in the control group (in six of the 19 women) than in the test group (in one of the 17 women).

Defective haemochorial placentation as a cause of miscarriage: a preliminary study

The morphology of the placental bed in idiopathic sporadic and recurrent miscarriages was studied and the findings correlated with the fetal chromosomal pattern where possible. Defective development of haemochorial placentation, which was not necessarily linked with fetal chromosomal abnormality, was seen in association with some miscarriages. These preliminary results, not previously demonstrated, strongly support the concept that miscarriages and pregnancies complicated by pre-eclampsia and/or small-for-gestational-age infants may be a continuum of disorders with a similar pathology in the placental bed.

The placental bed biopsy: review from three European centers

This review derives from extensive experience with the placental bed biopsy technique in three centers over the last 30 years. A placental bed biopsy, usually taken at cesarean section, must include basal decidua and subjacent myometrium from the central zone of the placental site. Attention is drawn specifically to the sampling errors and to the pitfalls in morphologic interpretation of tissues, both maternal and fetal, that are continuously changing throughout the course of pregnancy. The features of the normal placental bed and of vascular lesions in pathologic pregnancies are briefly reviewed. Extension and elaboration of the technique and its more widespread use could contribute to the elucidation of many of the unresolved problems in human pregnancy.

Epithelium of the human chorion laeve in diabetes mellitus. Light and electron microscopic examination

The epithelium of human chorion laeve from pregnancies complicated by diabetes mellitus was examined under the light and electron microscopy. In comparison with normal chorion laeve, the epithelium of chorion laeve in diabetes mellitus shows the following morphological changes: The trophoblast cells display more microvilli and cell processes on their surface. Trophoblast cells with different cytoplasmic characteristics can be seen. Some display few organelles and large glycogen depositions; other are rich in organelles. Furthermore, some cells with electron dense filaments and few cell organelles can be found. Necrotic cells are frequently present in the outer epithelial layers. The intercellular spaces in the epithelial layers near the basement membrane are narrower. Since vasculopathy of the decidual arteries with disturbance of blood circulation is often found in pathological pregnancies, we assume that the morphological changes found are due to deficiency in nutrient and oxygen supply.

Immunological studies of human trophoblast: markers, subsets and functions

People have many different reasons for wanting to know how the allogeneic relationship in normal human pregnancy is successful, but this question is far from being answered. Meanwhile, investigators will continue to use the ideas, approaches and tools with which they have experience and in which they have placed their confidence. Some study the factors which regulate immune functions in the fetus (for review see Murgita & Wigzel 1981); other focus more on the mother (for review see Rocklin et al. 1979); while yet others examine specialized aspects of abnormal pregnancies such as spontaneous abortion (Gill 1983). Although no one knows how the system operates to favor pregnancy, our particular bias is that trophoblast is the driving force which makes it work; for, without trophoblast, there is no pregnancy. This prejudice grew from our early observations of immunopathology in normal placentae (McCormick et al. 1971, Faulk et al. 1974, Faulk et al. 1980b, and reviewed by Faulk & Fox 1982) and was extended and amplified by experiments which showed that trophoblast, as well as antibodies to trophoblast, were able to impede allogeneic recognition as measured by specific inhibition of the mixed lymphocyte culture reaction (McIntyre & Faulk 1979 & 1979a). For a variety of reasons, many laboratories became interested in trophoblast-antigen biochemistry, and a burst of publications appeared on this subject (Faulk et al. 1977, Whyte & Loke 1979, Ogbimi et al. 1979, see review by Johnson et al. 1980). Some of this work confirmed and extended an earlier hypothesis from our laboratory that trophoblast membranes could serve as a hapten-carrier system where one group of trophoblast antigens (TA1) was the carrier, and a second group (TA2) was the hapten (Faulk et al. 1978). This hypothesis invoked a concept of trophoblast-lymphocyte cross-reactive antigens, an idea which was subsequently confirmed biochemically by showing human placental cell-surface antigens on peripheral blood lymphocytes (Hamilton et al. 1980). McIntyre and Faulk (1982, 1982a) later showed that these antigens were allotypic, and data have been provided in the above paragraphs to show that these components of trophoblast membranes are capable of serving as immunogens to stimulate the mother to mount immune recognition of her blastocyst. Indeed, it is presently our interpretation that successful nidation depends upon maternal recognition of the blastocyst, and that a lack of recognition results in spontaneous abortion, sometimes occurring so early that the mother is not aware that she was pregnant (Miller et al. 1980).(ABSTRACT TRUNCATED AT 400 WORDS)

An ultrastructural study of utero-placental spiral arteries in hypertensive and normotensive pregnancy and fetal growth retardation

Uteroplacental spiral arteries in placental bed biopsies and placentas form 80 pregnancies were studied by light and electron microscopy; of these 30 were complicated by fatal growth retardation(less than 10th centile) and 45 by hypertension during pregnancy. The physiological changes of the spiral arteries and the vascular pathology present in hypertensive pregnancy and fetal growth retardation were investigated. In normotensive pregnancies complicated by fetal growth retardation, the physiological changes of pregnancy frequently did not extend beyond the decidual segments of the utero-placental arteries. In pregnancies complicated by pre-eclampsia, the physiological changes of pregnancy were not always restricted to the decidual segments of the utero-placental arteries. Atheromatous-like lesions of similar morphology were found in spiral arteries from both normotensive and hypertensive pregnancies complicated by fetal growth retardation. No arteriopathy was found which was specific for pre-eclampsia.