Cord coiling, umbilical cord insertion and placental shape in an unselected cohort delivering at term: relationship with common obstetric outcomes

Maternal COVID-19 exposure and placental characteristics

INTRODUCTION

The impact of COVID-19 on the placenta is poorly described, particularly among minority women.

MATERIALS AND METHODS

This is a retrospective case-control study. Micro- and macroscopic placental pathologic findings were compared for 15 COVID-19 positive and 36 negative mothers. Cases and controls were frequency matched on gestational age, race, maternal comorbidities, and delivery type. Data from the electronic medical record were supplemented with independent review of microscopic slides.

RESULTS

Placentas from cases and controls were similar except the median distance from the site of the cord insertion to the nearest disk margin was statistically significantly shorter among placentas from COVID-19 positive cases (3.5 versus 6.0 cm, p = 0.006). Case status was not associated with an increased risk of placental pathologies.

CONCLUSION

There are few pathologic differences between placentas of COVID-19 positive and negative mothers. Additional studies are needed to investigate the role of timing of infection.

Prediction of postnatal abnormal umbilical cord coiling by antenatal evaluation in pregnant women: Diagnostic accuracy study; a systematic review

STUDY OBJECTIVE

Umbilical cord abnormalities increase neonatal morbidity and mortality. Considering uncertainties about the best time of an antenatal ultrasonography scan to evaluate the umbilical coiling index (UCI), this systematic review was designed to assess the diagnostic accuracy value of antenatal ultrasound assessments to predict abnormal postpartum UCI.

METHODS

All observational, cross-sectional, case-control, cohort, and diagnostic accuracy studies up to March 26, 2022, were searched and assessed according to PRISMA guidelines in Ovid, Cochrane, Scopus, PubMed, Web of Science, Embase, Proquest, Science Direct, and Clinical Key databases, and Google Scholar search engine.

RESULTS

The total number of 63 190 documents were retrieved from databases. The duplicates (19 272) were removed, 43 918 articles were screened for relevance, and 56 papers were selected for full-text evaluation, resulting in 14 qualified pieces subjected to the quality CASP tools for each type of study. Finally, six articles were evaluated, extracted, and confirmed. Overall, we had 16 evaluations (11 normal pregnancies, 4 gestational diabetes mellitus, and 1 group at risk for small gestational age), from which 9 and 7 were respectively performed in the second and third trimesters. Most of the evaluations considered both hypocoiling and hypercoiling. The sensitivity, specificity, and area under curves (AUCs) change range between the evaluations were 0.09-0.97, 0.59-0.96, and 0.262-0.84, respectively.

CONCLUSION

Observing any coiling abnormalities in every trimester, both the second and third, is highly sensitive to predicting abnormal postnatal UCI (pUCI). Conclusively, any detected antenatal abnormality is worth attention. Both trimesters' evaluations are essential, and no superiority is seen for any of them. The systematic review revealed statistical and clinical heterogeneity; a meta-analysis was impossible.

Placental structural abnormalities in gestational diabetes and when they develop: A scoping review

Gestational diabetes mellitus (GDM) is defined as diabetes with onset or first recognition during gestation. It is a common complication of pregnancy that has become more prevalent over the past few decades. Abnormalities in fetal growth, including increased incidence of both large and small for gestational age babies, suggest placental dysfunction. The major goal of this scoping review is to determine what is known about abnormalities in placentas delivered from GDM pregnancies, and how early in gestation these abnormalities arise. A secondary goal is to review to what extent other selected factors, in particular obesity, have been found to influence or modify the reported effects of GDM on placental development, and whether these are considered in the study of GDM placentas. PubMed and Scopus databases were searched using the key terms: "gestational diabetes AND (woman OR human) AND placenta AND (ultrasound OR ultrastructure OR imaging OR histology OR pathology). Studies of gross morphology and histoarchitecture in placentas delivered from GDM pregnancies consistently report increased placental size, villous immaturity and a range of vascular lesions when compared to uncomplicated pregnancies. In contrast, a small number of ultrasound studies have examined placental development in GDM pregnancies in the second, and especially, the first trimester. Relatively few studies have analyzed interactions with maternal BMI, but these do suggest that it may play a role in placental abnormalities. Further examination of placental development early in pregnancy is needed to understand when it becomes disrupted in GDM, as a first step to identifying the underlying causes.

Umbilical cord characteristics and their association with adverse pregnancy outcomes: A systematic review and meta-analysis

Objective

Current data on the role of the umbilical cord in pregnancy complications are conflicting; estimates of the proportion of stillbirths due to cord problems range from 3.4 to 26.7%. A systematic review and meta-analysis were undertaken to determine which umbilical cord abnormalities are associated with stillbirth and related adverse pregnancy outcomes.

Methods

MEDLINE, EMBASE, CINAHL and Google Scholar were searched from 1960 to present day. Reference lists of included studies and grey literature were also searched. Cohort, cross-sectional, or case-control studies of singleton pregnancies after 20 weeks’ gestation that reported the frequency of umbilical cord characteristics or cord abnormalities and their relationship to stillbirth or other adverse outcomes were included. Quality of included studies was assessed using NIH quality assessment tools. Analyses were performed in STATA.

Results

This review included 145 studies. Nuchal cords were present in 22% of births (95% CI 19, 25); multiple loops of cord were present in 4% (95% CI 3, 5) and true knots of the cord in 1% (95% CI 0, 1) of births. There was no evidence for an association between stillbirth and any nuchal cord (OR 1.11, 95% CI 0.62, 1.98). Comparing multiple loops of nuchal cord to single loops or no loop gave an OR of 2.36 (95% CI 0.99, 5.62). We were not able to look at the effect of tight or loose nuchal loops. The likelihood of stillbirth was significantly higher with a true cord knot (OR 4.65, 95% CI 2.09, 10.37).

Conclusions

True umbilical cord knots are associated with increased risk of stillbirth; the incidence of stillbirth is higher with multiple nuchal loops compared to single nuchal cords. No studies reported the combined effects of multiple umbilical cord abnormalities. Our analyses suggest specific avenues for future research.

Placental vascular tree characterization based on ex-vivo MRI with a potential application for placental insufficiency assessment

INTRODUCTION

Understanding regarding the whole placental vascular network structure is limited. Our aim was to quantitatively characterize the human placental vascular tree ex-vivo using high-resolution MRI.

METHODS

34 normal placentas were rinsed and injected with a solution of gelatin and contrast agent through the umbilical vessels. A sample of six placentas taken from pregnancies with intrauterine-growth-restriction (IUGR) was used to demonstrate the potential application to cases with placental insufficiency. Structural ex-vivo MR scans of the placenta were performed using high resolution T₁ weighted images. A semi-automatic method was developed to segment and characterize the placental vascular architecture: placental volume and cord insertion location; number of bifurcations, generations and vessels diameters.

RESULTS

Different vascular patterns were found in placentas with central versus marginal cord-insertion. Based on the placental volume and number of bifurcations we were able to predict birth weight. Furthermore, preliminary results on IUGR sample demonstrated the potential of this method to differentiate between small newborns with suspected IUGR from small normal newborns who reached their full growth potential. Results obtained using the automatic method were validated against manual values demonstrating no significant differences or bias. Histopathology supported the imaging findings.

DISCUSSION

This is the first study to quantitatively characterize the human placental vascular architecture using high resolution ex-vivo MRI. Different patterns of vascular architecture may be related to different functioning of the placenta and affect fetal development. This method is simple, relatively fast, provides detailed information of the placental vascular architecture, and may have important clinical applications.

Histomorphological changes of the placenta and umbilical cord in pregnancies complicated by gestational diabetes mellitus

INTRODUCTION

The objective of this study was to compare the histomorphological changes of placenta and umbilical cord (UC), between gestational diabetes mellitus (GDM) and non- GDM pregnancies.

METHODS

In this prospective study, 222 parturients were recruited (117 GDM and 105 non-GDM). GDM was confirmed at 24-28 weeks of gestation, using one-step strategy. A full record of demographic, laboratory, histologic and gross morphology data of placenta and UC was extracted and analyzed.

RESULTS

Overall, 222 placentas/UCs met inclusion criteria. The mean (SD) of gestational age of GDM diagnosis was 20.68 (10.02) and the GDM duration was 16.76 (8.98) weeks. The mean HbA1C was 6.03 (0.41) % in the GDM group. The gross morphology findings including UC diameter and thick edematous UC differed significantly between two groups and more presented in GDM group, 1.41 (0.03) vs. 1.28 (0.03) centimeters; p-value = 0.006 and 34.19% vs. 16.19%; p-value = 0.002, respectively. The umbilical coiling index (UCI) was similar in two groups (p-value = 0.61). In the histological evaluation, persistence of central vessels differed significantly between two groups, more detected in non-GDM (47.62% vs. 32.97%; p-value = 0.04). No other significant histomorphological changes were detected between two groups.

DISCUSSION

This study showed that gross morphologic features such as UC diameter increment and thick edematous UC happened more frequently, among the GDM parturients. Due to early diagnosis, diagnosis strategy, and optimal glycemic control, the histomorphological changes were less in GDM comparing of non-GDM group.

Placental vascular tree characterization based on ex-vivo MRI with a potential application for placental insufficiency assessment

INTRODUCTION

Understanding regarding the whole placental vascular network structure is limited. Our aim was to quantitatively characterize the human placental vascular tree ex-vivo using high-resolution MRI.

METHODS

34 normal placentas were rinsed and injected with a solution of gelatin and contrast agent through the umbilical vessels. A sample of six placentas taken from pregnancies with intrauterine-growth-restriction (IUGR) was used to demonstrate the potential application to cases with placental insufficiency. Structural ex-vivo MR scans of the placenta were performed using high resolution T₁ weighted images. A semi-automatic method was developed to segment and characterize the placental vascular architecture: placental volume and cord insertion location, number of bifurcations, generations and vessels diameters.

RESULTS

Different vascular patterns were found in placentas with central versus marginal cord-insertion. Based on the placental volume and number of bifurcations we were able to predict birth weight. Furthermore, preliminary results on IUGR sample demonstrated the potential of this method to differentiate between small newborns with suspected IUGR from small normal newborns who reached their full growth potential. Results obtained using the automatic method were validated against manual values demonstrating no significant differences or bias. Histopathology supported the imaging findings.

DISCUSSION

This is the first study to quantitatively characterize the human placental vascular architecture using high resolution ex-vivo MRI. Different patterns of vascular architecture may be related to different functioning of the placenta and affect fetal development. This method is simple, relatively fast, provides detailed information of the placental vascular architecture, and may have important clinical applications.

Gestational diabetes mellitus: the correlation between umbilical coiling index, and intrapartum as well as neonatal outcomes

Objectives

The objective of this study was to investigate the relationship between the postnatal umbilical coiling index (pUCI), and intrapartum and neonatal outcomes in parturients with gestational diabetes mellitus (GDM) and non-GDM.

Methods

An evaluation of the umbilical cords and pUCI of 117 neonates of GDM and 105 of non-GDM parturients were prospectively studied within 24 h after delivery. Furthermore, obstetric history, intrapartum and neonatal data were recorded.

Results

Premature rupture of membrane (PROM) (p = 0.001), emergency cesarean delivery (p = 0.01), spontaneous preterm delivery (p = 0.006), duration of hospital admission (p < 0.001), and congenital malformations (p = 0.03) were significantly higher in the GDM group. Moreover, pUCI had a significant association with large for gestational age (LGA) (p = 0.009), and meconium-stained amniotic fluid (p = 0.04) in the GDM group. In addition, increment of pUCI had significant association with spontaneous preterm delivery in both groups (p = 0.002) (OR = 1.23).

Conclusions

GDM is associated with spontaneous preterm delivery, PROM, emergency cesarean delivery, duration of hospital admission, and congenital malformations. Increase in pUCI could increase the rate of spontaneous preterm delivery in normal pregnancy and pregnancy complicated by GDM, as well as, the rate of LGA and meconium-stained amniotic fluid in GDM.

Associations Between the Features of Gross Placental Morphology and Birthweight

The placenta plays a critical role in regulating fetal growth. Recent studies suggest that there may be sex-specific differences in placental development. The purpose of our study was to evaluate the associations between birthweight and placental morphology in models adjusted for covariates and to assess sex-specific differences in these associations. We analyzed data from the Stillbirth Collaborative Research Network's population-based case-control study conducted between 2006 and 2008, which recruited cases of stillbirth and population-based controls in 5 states. Our analysis was restricted to singleton live births with a placental examination (n = 1229). Characteristics of placental morphology evaluated include thickness, surface area, difference in diameters, shape, and umbilical cord insertion site. We used linear regression to model birthweight as a function of placental morphology and covariates. Surface area had the greatest association with birthweight; a reduction in surface area of 83 cm², which reflects the interquartile range, is associated with a 260.2-g reduction in birthweight (95% confidence interval, -299.9 to -220.6), after adjustment for other features of placental morphology and covariates. Reduced placental thickness was also associated with lower birthweight. These associations did not differ between males and females. Our results suggest that reduced placental thickness and surface area are independently associated with lower birthweight and that these relationships are not related to sex.

Antenatal umbilical coiling index in gestational diabetes mellitus and non-gestational diabetes pregnancy

OBJECTIVE

Umbilical cord abnormalities increase fetal morbidity and mortality. This study was designed to compare antenatal umbilical coiling index (aUCI) in gestational diabetes mellitus (GDM) and non-gestational diabetes mellitus (non-GDM) pregnancy, considering uncertainties about the best time to perform antenatal ultrasonography scan.

MATERIALS AND METHODS

In this prospective study, 246 parturients were included, 123 with GDM and 123 with non-GDM pregnancy. Gestational diabetes was confirmed at 24-28 weeks of gestation (WG) using one-step strategy. An anatomical ultrasound survey of placenta and umbilical cord was performed at 18-23 as well as 37-41 weeks of gestational age.

RESULTS

At 18-23 WG, the frequency distribution (10th, 90th percentiles, mean ± SD) of the aUCI in the GDM and non-GDM groups were (0.13,0.66,0.32 ± 0.19) and (0.18,0.74, 0.4 ± 0.31) respectively. These values were (0.12,0.4, 0.25 ± 0.11) in the GDM group at 37-41 WG and (0.17,0.43, 0.29 ± 0.11) in the non-GDM group. A significant relationship was detected between UCI value and GDM/non-GDM groups at both antenatal evaluations (18-23 WG; P = 0.002, 37-41WG; P < 0.001). A significant association at 18-23 WG was found between GDM/non-GDM groups and aUCI categorization (hypocoiling <10th, normocoiling 10th-90th and hypercoiling >90th) (P = 0.001). However, hypocoiling were significantly more frequent in GDM than non-GDM in both antenatal evaluations (P < 0.001, P = 0.006).

CONCLUSION

Antenatal UCI in pregnancy complicated by GDM were lower in comparison with non-GDM pregnancy. The most abnormal pattern of coiling in gestational diabetes was hypocoiling in both trimesters. In addition, 18-23 WG is the best time to perform ultrasound scan to detect aUCI and umbilical cord pattern.

Prediction of postnatal abnormal coiling of the umbilical cord in gestational diabetes mellitus: a diagnostic accuracy study

Objective: To investigate whether evaluations of antenatal umbilical coiling index (aUCI) could predict postnatal umbilical coiling index (UCI) (pUCI) in people with gestational diabetes mellitus (GDM) compared with normal pregnancy independent of maternal demographic and reproductive characteristics.Method: In this prospective study, 105 women with normal pregnancy, and 117 women with pregnancy complicated by GDM were recruited. Ultrasound scan of umbilical cord was performed at 18-23 and 37-41 weeks of gestation (WG). Evaluation of pUCI, as the reference standard, was performed within 24 hours after delivery.Findings: There was no significant relationship between aUCI and maternal demographic and reproductive characteristics. The mean for pUCI was 0.21 ± 0.12 in the GDM group, and 0.21 ± 0.09 in the normal pregnancy (p = .61). In the GDM group, a significant association was found between aUCI and pUCI categories (p = .004). The area under curve (AUC) was less than 0.5 for hypocoiling in both groups. For hypercoiling it was 0.84 ± 0.04 in the GDM group and 0.75 ± 0.06 in the normal pregnancy group (18-23 WG). In the GDM group the cutoff points that predict hypercoiling were 0.28 (18-23WG), and 0.21 (37-41WG). These were 0.35 (18-23WG), and 0.33 (37-41WG) in the normal pregnancy group. Diagnostic accuracy analysis revealed that in the GDM group, the sensitivity and specificity of hypercoiling for prediction of pUCI were 0.94 and 0.70 respectively at 18-23 WG.Conclusions: Antenatal hypercoiling at the second trimester of pregnancy strongly predict postnatal hypercoiling in pregnancies complicated by GDM.

Advances in Human Placental Biomechanics

Pregnancy complications are a major clinical concern due to the related maternal and fetal morbidity. Many are caused through defective placentation, but research into placental function is difficult, principally because of the ethical limitations associated with the in-vivo organ and the difficulty of extrapolating animal models. Perfused by two separate circulations, the maternal and fetal bloodstreams, the placenta has a unique structure and performs multiple complex functions. Three-dimensional imaging and computational modelling are becoming popular tools to investigate the morphology and physiology of this organ. These techniques bear the potential for better understanding the aetiology and development of placental pathologies, however, their full potential is yet to be exploited. This review aims to summarize the recent insights into placental structure and function by employing these novel techniques.

Morphological and ultrastructural changes in the placenta of the diabetic pregnant Egyptian women

Diabetes mellitus (DM) is a chronic metabolic disease in which the body fails to produce enough insulin or increased tissue resistance to insulin. The diabetes may have profound effects on placental development and function. This study was designed to detect the placental changes in pregnancy associated with DM comparing these changes with normal placenta. The study was carried out on sixty full-term placentae; divided into three equal groups; control group (group I): placentae of normal pregnancy, uncontrolled diabetes (group II): placentae from pregnant women whose blood glucose is poorly controlled during pregnancy. Controlled diabetes (group III): includes placentae from diabetic women whose blood glucose is controlled during pregnancy. The placentae from group II tend to be heavier and exhibited immaturity of villi, villous edema, fibrosis, excessive syncytial knots formation and infarctions. In addition to, fibrinoid necrosis, increased thickness of vasculosyncytial membrane, syncytial basement membrane, microvillous abnormalities and vascular endothelial changes were demonstrated. The syncytial multivesicular knots were present in placentae of group II. The nuclei within these syncytial knots display condensed chromatin, either dispersed throughout the nucleus or in the form of dense peripheral clumps with and numerous cytoplasmic vacuoles. The syncytial basement membrane showed focal areas of increase in its thickness and irregularity. Villous cytotrophoblasts showed increased number and activity in the form of numerous secretory granules, abundant dilated RER, larger distorted mitochondria. Villous vessels showed various degrees of abnormalities in the form of endothelial cell enlargement, folding, thickening and protrusion of their luminal surfaces into vascular lumen making it narrower in caliber. In placentae of group III, most of these abnormalities decreased. In most of placentae of group III, the VSM appeared nearly normal in thickness and showed nearly normal composition of one layer of syncytiotrophoblastic cells, one layer of smooth, regular capillary endothelium and the space between them. Mild microvillous abnormalities were noted in few placentae as they appeared short and blunted with mild decrease in their number per micron. The electron picture of syncytial knots appeared nearly normal containing aggregations of small, condensed hyperchromatic nuclei, minimal vacuoles could be seen in the cytoplasm of syncytial knots. Syncytial basement membrane appeared regular and nearly normal in its thickness and composition coming in direct contact with fetal blood capillaries but mild abnormalities were noted in the basement membrane in few placentae as increased its thickness and deposition of fibers or fibrinoid. Regarding cytotrophoblasts in the terminal villi of placentae with controlled diabetes, these cells appeared nearly normal. They were scattered beneath the syncytium and were active containing mitochondria, rough endoplasmic reticulum, free ribosomes and a large nucleus with fine dispersed chromatin. The vascular ultrastructural pattern in terminal villi of placentae of this group showed no significant abnormalities and was normally distributed in the villous tree. The luminal surface of the vascular endothelium appeared regular smooth in the majority of placentae of this group. The endothelial cells appeared connected to each other with tight junctions. It could be concluded that whether if long-term diabetes is controlled or not, placentae of diabetic mother showed a variety of significant histological structural changes seen more frequently than in the placentae of pregnant women without diabetes.

Second trimester marginal cord insertion is associated with adverse perinatal outcomes

Objectives: To determine the feasibility in visualizing placental cord insertion (PCI) during second-trimester fetal anatomical survey and the association between marginal cord insertion (MCI) and preterm delivery (PTD) and low birth weight (LBW). Our secondary objectives were to evaluate the association of MCI with adverse composite obstetrical and neonatal outcomes. Methods: A prospective cohort study was performed over a 28-month period. Women with singleton pregnancies presenting for routine anatomical survey between 18 and 22 weeks' gestation were included. PCI site was visualized on 2D grayscale and color Doppler and the shortest distance from the sagittal and transverse planes to the placental edge were recorded. MCI was diagnosed when any of measured distances was ≤2 cm. Correlations were assessed via bivariate chi-squared, independent t-test analyses and Fisher's exact tests. Regression models evaluated associations between MCI and adverse composite outcomes. Results: Three hundred one women were included and PCI was feasible in all cases. The incidence of MCI was 11.3% (n = 34). Baseline characteristics between those with and without MCI were similar, except for story of prior PTD, which was greater among those with MCI (17.65 versus 7.17%, p = .04). MCI was associated with increased likelihood of LBW (RR four; 95%CI, 1.46-10.99) and PTD (RR 3.2; 95%CI, 1.53-6.68); in multivariate analysis, we found associations between MCI and composite adverse obstetrical (RR 2.33; 95%CI, 1.30-4.19) and neonatal (RR 2.46; 95%CI, 1.26-4.81) outcomes. Conclusions: Evaluation of PCI is feasible in all cases. Second-trimester MCI is associated with increased likelihood for LBW, PTD, and composite adverse obstetrical and neonatal outcomes.

Eccentric placentae have reduced surface area and are associated with lower birth weight in babies small for gestational age

Placental structure and function determine birth outcomes. Placental mass does not always correlate with fetal birth weight (BW) in uncomplicated pregnancies which raises the possibility of other variables such as placental shape and cord insertion being the determinants of placental efficiency. In total, 160 women with singleton pregnancy, recruited into a pregnancy cohort were studied. Placental weight (PW) was measured and other data were obtained from clinical records. Birth outcomes were classified as small for gestational age (SGA) and appropriate for gestational age (AGA) based on fetal gender, gestational age (GA) and BW. High-resolution images of the chorionic plate were recorded. The shape of the placenta and the insertion of the cord were measured using eccentricity index (EI) and cord centrality index (CCI). Only placentae with eccentrically inserted cords (n=136) were included. The mean BW and PW were 2942 (±435) g and 414 (±82) g with average GA of 38.6 weeks. The mean CCI and EI was 0.483 (±0.17) and 0.482 (±0.16). Neither of these correlated with placental efficiency. However, EI showed negative correlation with placental surface area and breadth. Upon sub-grouping the cohort into SGA (n=32) and AGA (n=104), the SGA babies with the highest EI (third tertile) had significantly lower BW than those with the least eccentric placentae (first tertile). Although eccentric-shaped placentae were present in both SGA and AGA groups, the effect on BW was observed only in the SGA group.

Hemodynamic analysis of blood flow in umbilical artery using computational modeling

The umbilical cord is the crucial pathway for blood flow between the fetus and the placenta. Umbilical coiling and length have been separately linked to adverse clinical outcomes; however, the effects of variations of these parameters on umbilical arterial blood flow are not well understood. Using 3D computational model, we studied the individual and combined effects of umbilical coiling index, cord length and arterial diameter on umbilical artery hemodynamics. We found that specific combinations of umbilical coiling index, cord length and arterial diameter yielded pressure and flow drops incompatible with fetal life. Such models are useful as hypothesis-developing tools.

Placental Origins of Chronic Disease

Epidemiological evidence links an individual's susceptibility to chronic disease in adult life to events during their intrauterine phase of development. Biologically this should not be unexpected, for organ systems are at their most plastic when progenitor cells are proliferating and differentiating. Influences operating at this time can permanently affect their structure and functional capacity, and the activity of enzyme systems and endocrine axes. It is now appreciated that such effects lay the foundations for a diverse array of diseases that become manifest many years later, often in response to secondary environmental stressors. Fetal development is underpinned by the placenta, the organ that forms the interface between the fetus and its mother. All nutrients and oxygen reaching the fetus must pass through this organ. The placenta also has major endocrine functions, orchestrating maternal adaptations to pregnancy and mobilizing resources for fetal use. In addition, it acts as a selective barrier, creating a protective milieu by minimizing exposure of the fetus to maternal hormones, such as glucocorticoids, xenobiotics, pathogens, and parasites. The placenta shows a remarkable capacity to adapt to adverse environmental cues and lessen their impact on the fetus. However, if placental function is impaired, or its capacity to adapt is exceeded, then fetal development may be compromised. Here, we explore the complex relationships between the placental phenotype and developmental programming of chronic disease in the offspring. Ensuring optimal placentation offers a new approach to the prevention of disorders such as cardiovascular disease, diabetes, and obesity, which are reaching epidemic proportions.

Ultrasonographic evaluation of placental cord insertion at different gestational ages in low-risk singleton pregnancies: a predictive algorithm

OBJECTIVE

To evaluate the accuracy of ultrasound in visualizing placental cord insertion (PCI) at different gestational ages in order to recommend the most feasible period during pregnancy to identify it. Secondary aim was to propose a predictive algorithm for PCI visualization.

METHODS

We performed a single-center, prospective cohort study. We enrolled patients with singleton low-risk pregnancies who underwent fetal ultrasound scan at different gestational ages. We excluded patients with body mass index of 30 Kg/m2 or more, uterine fibroids larger than 5 cm, high-risk pregnancies, fetal weight lower than < 10° percentile or higher than > 90° percentile, increased ("deep pocket" > 80 mm) or decreased ("deep pocket" < 20 mm) amniotic fluid.

RESULTS

Among the 468 recruited patients, the visualization of PCI was not possible in 5.77% of the cases. Furthermore, we showed that PCI visualization was lower as the gestational age increased (p = 0.049) and more difficult in case of posterior placenta (p = 0.001).

CONCLUSIONS

PCI should be evaluated in the first trimester or as early as possible during the second trimester. Moreover, we propose a feasible model to predict the possibility of PCI visualization according to gestational age and uterine site of implantation.

Funisitis is associated with adverse neonatal outcome in low-risk unselected deliveries at or near term

This study aimed to determine the incidence and clinical outcomes for varying patterns of placental histological inflammation (consistent with fetal or maternal inflammatory response) in an unselected population of >1000 women with a singleton pregnancy resulting in live birth delivering at or near term. One thousand one hundred nineteen cases were studied in a blind, prospective, unselected study with placentas categorized into five histological subgroups reflecting underlying maternal or fetal inflammatory response. Clinical outcomes studied included interventional delivery, an Apgar score <7 at 1 min, neonatal acidosis (pH < 7.2) and admission to neonatal special care. One hundred eighty-eight placentas (17 %) showed histological evidence of acute inflammation: 64 with funisitis (with or without other inflammation; 6 %); 16 with extensive acute inflammation across the chorionic plate, free membranes and subchorionic fibrin (1 %); 28 with acute inflammation restricted to the chorionic plate (2 %); 12 with acute inflammation restricted to the free membranes (1 %) and 68 with acute inflammation restricted to the subchorionic fibrin (6 %). Features of extensive acute inflammation were significantly associated with increased rate of interventional delivery (assisted vaginal delivery or emergency caesarean section; P < 0.01). The presence of funisitis was significantly associated with interventional delivery and other adverse outcomes including an Apgar score <7 at 1 min, clinical evidence of sepsis and admission to the neonatal intensive care unit (P < 0.05 for all). The data represent a quantitative rather than purely qualitative analysis of the contribution of histological lesions related to inflammation on short-term adverse neonatal outcomes and interventional delivery. Funisitis and extensive inflammation are associated with adverse clinical outcomes, but the precise mechanism underlying these remains to be elucidated.

Multiscale modelling of the feto-placental vasculature

The placenta provides all the nutrients required for the fetus through pregnancy. It develops dynamically, and, to avoid rejection of the fetus, there is no mixing of fetal and maternal blood; rather, the branched placental villi 'bathe' in blood supplied from the uterine arteries. Within the villi, the feto-placental vasculature also develops a complex branching structure in order to maximize exchange between the placental and maternal circulations. To understand the development of the placenta, we must translate functional information across spatial scales including the interaction between macro- and micro-scale haemodynamics and account for the effects of a dynamically and rapidly changing structure through the time course of pregnancy. Here, we present steps towards an anatomically based and multiscale approach to modelling the feto-placental circulation. We assess the effect of the location of cord insertion on feto-placental blood flow resistance and flow heterogeneity and show that, although cord insertion does not appear to directly influence feto-placental resistance, the heterogeneity of flow in the placenta is predicted to increase from a 19.4% coefficient of variation with central cord insertion to 23.3% when the cord is inserted 2 cm from the edge of the placenta. Model geometries with spheroidal and ellipsoidal shapes, but the same volume, showed no significant differences in flow resistance or heterogeneity, implying that normal asymmetry in shape does not affect placental efficiency. However, the size and number of small capillary vessels is predicted to have a large effect on feto-placental resistance and flow heterogeneity. Using this new model as an example, we highlight the importance of taking an integrated multi-disciplinary and multiscale approach to understand development of the placenta.

A stochastic model for early placental development

In the human, placental structure is closely related to placental function and consequent pregnancy outcome. Studies have noted abnormal placental shape in small-for-gestational-age infants which extends to increased lifetime risk of cardiovascular disease. The origins and determinants of placental shape are incompletely understood and are difficult to study in vivo. In this paper, we model the early development of the human placenta, based on the hypothesis that this is driven by a chemoattractant effect emanating from proximal spiral arteries in the decidua. We derive and explore a two-dimensional stochastic model, and investigate the effects of loss of spiral arteries in regions near to the cord insertion on the shape of the placenta. This model demonstrates that disruption of spiral arteries can exert profound effects on placental shape, particularly if this is close to the cord insertion. Thus, placental shape reflects the underlying maternal vascular bed. Abnormal placental shape may reflect an abnormal uterine environment, predisposing to pregnancy complications. Through statistical analysis of model placentas, we are able to characterize the probability that a given placenta grew in a disrupted environment, and even able to distinguish between different disruptions.

Gestational diabetes as one of the "great obstetrical syndromes"--the maternal, placental, and fetal dialog

Gestational diabetes mellitus (GDM)-associated fetal and neonatal adverse outcome results from the metabolic milieu projected on the fetus via the placental interface. Therefore, it can be considered to be one of the great obstetrical syndromes. Placentas from GDM pregnancies differ from nondiabetic pregnancies by an increased placental to fetal ratio and by histological findings such as villous fibrinoid necrosis, villous immaturity, chorangiosis, and ischemic changes. While early onset diabetes is more associated with marked structural changes of the placenta, GDM that rises at late gestation is associated more with placental functional changes. These placental changes, causing increased intervillous diffusion distance of immature villi and placental size to perfusion mismatch, may predispose the fetus to chronic and acute changes in gas and nutrient exchange thus turning the placenta from being a "fetus protector" to a potential source of adverse outcome. Understanding placental changes and how they affect outcome is necessary in order to develop effective screening, prevention, and management approaches.

Umbilical cord coiling: clinical outcomes in an unselected population and systematic review

This study was conducted to determine the frequency of pre-defined clinical outcomes in relation to umbilical cord coiling indices >90th percentile and <10th percentile in an unselected population of >1,000 women with a singleton pregnancy resulting in livebirth delivering at or near term and to report these findings in the context of a systematic review. Placentas of consecutive deliveries from an unselected low-risk population with >15 cm attached umbilical cords were included in the study. Clinical outcomes included interventional delivery, birthweight <10th percentile, Apgar score <7 at 1 min, neonatal acidosis (pH<7.2) and admission to neonatal special care. Standard MOOSE (Meta-analysis of Observational Studies in Epidemiology) guidelines were observed for the systematic review. Umbilical coiling index was determined for 1,082 placentas. Mean maternal age was 30.7 years (standard deviation [SD] =5.7) and 519 women (48 %) were primiparous. Mean cord length was 43 cm (SD=13) and mean cord coiling index 0.20 (SD=0.09). A total of 866 cords were normally coiled, and 108 cases were hypercoiled (>90th centile) and 108 cases were undercoiled (<10th percentile). There were no differences between cases of overcoiled, normally coiled or undercoiled cords for any clinical outcome studied. The systematic review yielded a small number of clinical studies which were too statistically and clinically heterogenous to permit meta-analysis. There is insufficient evidence either from this unselected cohort study or from a systematic review to support the previous suggestion that cord coiling index >90th centile or <10th centile is associated with adverse clinical outcome in an unselected population. Previous studies that draw a link between abnormal cord coiling and clinical outcome are generally too small and/or selective to allow meaningful conclusions or applicability to low-risk populations.

Optimising sample collection for placental research

Biobanks provide an important repository of samples for research purposes. However, for those samples to reflect the in vivo state, and for experimental reliability and reproducibility, careful attention to collection, processing and storage is essential. This is particularly true for the placenta, which is potentially subjected to stressful conditions during delivery, and sample collection may be delayed owing to routine postpartum inspection by clinical staff. In addition, standardisation of the collection procedure enables samples to be shared among research groups, allowing larger datasets to be established. Here, we provide an evidence-based and experts' review of the factors surrounding collection that may influence data obtained from the human placenta. We outline particular requirements for specific techniques, and propose a protocol for optimal sample collection. We recognise that the relevance of these factors, and of the sample types collected to a particular study will depend on the research questions being addressed. We therefore anticipate that researchers will select from the protocol to meet their needs and resources available. Wherever possible, we encourage researchers to extend their collection to include additional samples that can be shared on an international collaborative basis, with appropriate informed consent, to raise the quality, as well as quantity, of placental research.

Macroscopic and microscopic findings of the placenta in women with polycystic ovary syndrome

STUDY QUESTION

Do patients with polycystic ovary syndrome (PCOS) have macroscopic and/or microscopic placental alterations?

SUMMARY ANSWER

The placental structure in patients with PCOS, even in those with uncomplicated pregnancy, is altered.

WHAT IS KNOWN ALREADY

The spectrum of pregnancy complications seems to have a common denominator: a defective trophoblast invasion and placentation. In women with PCOS, alterations in endovascular trophoblast invasion related to insulin resistance and hyperandrogenism have been observed.

STUDY DESIGN, SIZE, DURATION

For this prospective case-control study, 30 pregnant patients with PCOS (cases) and 60 healthy pregnant women without PCOS features (controls) were enrolled and studied until delivery. Clinical, biochemical, ultrasonographic and obstetric data were recorded. The baseline clinical and biochemical data for screening for PCOS and for inclusion/exclusion were obtained before the seventh week of gestation. At delivery, placentas were collected and detailed macroscopic and microscopic analyses were performed.

PARTICIPANTS, SETTING, METHODS

Cases and controls were matched for age and BMI (all <30 kg/m(2)). The matching procedure was one-to-two. Only subjects with spontaneous conception and uncomplicated pregnancies were included in the final analysis.

MAIN RESULTS AND THE ROLE OF CHANCE

Placental weight (P = 0.04), thickness (P = 0.02), density (P = 0.02) and volume (P = 0.01) were significantly inferior in women with, compared with those without PCOS. The placentas from patients with PCOS more frequently had an irregular shape (P = 0.03) and a higher cord coiling index (P = 0.02). Differences between cases and controls also concerned the extent of villous (P = 0.04) and intervillous (P = 0.01) spaces, the extent of fibrosis (P = 0.03), endovascular trophoblast (depth, extension and morphometry) (P < 0.05) and mitotic activity (P = 0.01). The percentage of patients with lesions [22/30 (73.3%) versus 25/60 (41.7%), respectively; P = 0.01] and the mean number of placental lesions (3.5 ± 2.1 versus 1.4 ± 1.1, respectively; P = 0.02) were higher in the PCOS than the control group. The odds ratio for placental alterations, adjusted for weight gain, was 2.8 (95% confidence interval 1.3-9.9).

LIMITATIONS, REASONS FOR CAUTION

The main limitation of the study was the selection of a specific PCOS sample, which is probably not representative of the PCOS phenotype as a whole. In fact, we excluded patients with PCOS who were obese and who achieved a pregnancy following the use of ovulation inductors or assisted reproduction techniques.

WIDER IMPLICATIONS OF THE FINDINGS

The present study is the first to demonstrate that the morphology and microscopic structure of placenta in patients with PCOS with an uncomplicated pregnancy are altered. Further studies are needed to assess a correlation of these changes with the increased risk of obstetric complications observed in some pregnancies of women with PCOS.

STUDY FUNDING/COMPETING INTEREST(S)

The authors declare no conflict of interest and no financial support for the research.

TRIAL REGISTRATION NUMBER

N/A.

Elsevier Trophoblast Research Award Lecture: Searching for an early pregnancy 3-D morphometric ultrasound marker to predict fetal growth restriction

Fetal growth restriction (FGR) is a major cause of perinatal morbidity and mortality, even in term babies. An effective screening test to identify pregnancies at risk of FGR, leading to increased antenatal surveillance with timely delivery, could decrease perinatal mortality and morbidity. Placental volume, measured with commercially available packages and a novel, semi-automated technique, has been shown to predict small for gestational age babies. Placental morphology measured in 2-D in the second trimester and ex-vivo post delivery, correlates with FGR. This has also been investigated using 2-D estimates of diameter and site of cord insertion obtained using the Virtual Organ Computer-aided AnaLysis (VOCAL) software. Data is presented describing a pilot study of a novel 3-D method for defining compactness of placental shape. We prospectively recruited women with a singleton pregnancy and BMI of <35. A 3-D ultrasound scan was performed between 11 and 13 + 6 weeks' gestation. The placental volume, total placental surface area and the area of the utero-placental interface were calculated using our validated technique. From these we generated dimensionless indices including sphericity (ψ), standardised placental volume (sPlaV) and standardised functional area (sFA) using Buckingham π theorem. The marker for FGR used was small for gestational age, defined as <10th customised birth weight centile (cSGA). Regression analysis examined which of the morphometric indices were independent predictors of cSGA. Data were collected for 143 women, 20 had cSGA babies. Only sPlaV and sFA were significantly correlated to birth weight (p < 0.001). Regression demonstrated all dimensionless indices were inter-dependent co-factors. ROC curves showed no advantage for using sFA over the simpler sPlaV. The generated placental indices are not independent of placental volume this early in gestation. It is hoped that another placental ultrasound marker based on vascularity can improve the prediction of FGR offered by a model based on placental volume.

The placenta and gestational diabetes mellitus

By its location between maternal and fetal bloodstreams the human placenta not only handles the materno-fetal transport of nutrients and gases, but may also be exposed to intrauterine conditions adversely affecting placental and fetal development. Such adverse conditions exist in pregnancies complicated by gestational diabetes mellitus (GDM), and have been associated with alterations in placental anatomy and physiology. These alterations are mainly based on changes on the micro-anatomical and/or even molecular level including aberrant villous vascularization, a disbalance of vasoactive molecules, and enhanced oxidative stress. The consequence thereof may be impaired fetal oxygenation and changes in transplacental nutrient supply. Although transplacental glucose flux is flow limited and independent of glucose transporter availability, transport of essential and nonessential amino acids and expression of genes involved in lipid transport and metabolism are significantly affected by GDM.

Frequency and clinical significance of placental histological lesions in an unselected population at or near term

Associations between specific placental histological abnormalities and obstetric outcomes are reported. However, most data are based either on high-risk cases or relate to case-control studies selected from those with abnormal placental histology findings, with the unavoidable biases that these approaches entail. This study reports the frequency of the several common, objective and predefined histological abnormalities of the placenta as identified by pathologists blinded to all clinical information. A total 1,153 women were recruited from an unselected population delivering at 34-43 weeks. Histological findings in common obstetric outcome groups were compared to those of the unselected population, and odds ratios and predictive values were calculated. Normal histological findings were present in 72.1% of pregnancies with normal outcomes and in 79.1%, 66.6%, 80%, and 74.8% of pregnancies affected by pre-eclampsia (PET), pregnancy-induced hypertension (PIH), gestational diabetes (GDM), and small for gestational age (SGA), respectively. Chronic placental underperfusion was seen more frequently in PIH (odds ratio (OR) 2) and SGA (OR 1.4), while villitis of unknown aetiology was observed more commonly in cases with PIH (OR 3.2). Fetal thrombotic vasculopathy was twice as common in cases with GDM whilst massive perivillous fibrin deposition was much more frequent in those with PET (OR 20.2) and SGA (OR 8.9). Chorangiomata were 13 times more common in pregnancies with PET. However, in all cases, positive predictive values were low, with the majority of cases with histological abnormalities being associated with normal outcome. At term, specific placental histological lesions are significantly more common in complicated pregnancies, but the clinical significance of such lesions in a specific case remains uncertain, since the majority will be identified from clinically uncomplicated normal pregnancies.

Relationship between placental morphology and histological findings in an unselected population near term

Whilst individual histological features are well described, there are no universally agreed criteria as to what constitutes a clinically significant histological lesion of the placenta in an uncomplicated pregnancy, nor has the presence of such histological findings been systematically related to quantitative morphological characteristics of the placenta (such as placental shape, cord insertion and cord coiling). This study aims to explore this relationship and further to describe the incidence of predefined categories of histological lesions of the placenta in an unselected obstetric population recruited prior to delivery. The study is based upon the placental examination of 1,156 women with singleton pregnancies recruited prospectively in a single unit. Placentas were analysed where deliveries occurred between 34-43 weeks. The incidence of normal histological findings and specific histological categories, such as ascending genital tract infection, chronic placental underperfusion, intervillous thrombus and villitis of unknown aetiology, were noted. The relationship between placental morphological indices: coiling index, cord centrality index (distance of cord insertion on the chorionic plate from the centre) and eccentricity (shape of the placenta) and histological lesions was investigated. There were no significant differences between cord centrality and eccentricity between placentas with and without histological lesions except an association between hypercoiling of the umbilical cord and intervillous thrombosis and villitis of unknown aetiology (p = 0.024 and p = 0.009, respectively). The macroscopic morphological features of the placenta cannot predict the presence or absence of the histological placental lesions, nor are these lesions in general associated with differences in cord centrality, placental eccentricity or cord coiling.