Background-Placentas are generally round-oval in shape, but "irregular" shapes are common. In the Collaborative Perinatal Project data, irregular shapes were associated with lower birth weight for placental weight, suggesting variably shaped placentas have altered function.

Goal: We assess the effect on placental efficiency of the non-centrality of the umbilical cord insertion and on chorionic vascular distribution to determine if cord centrality measurably affects placental function as reflected in birth weight. Materials and Methods:1,225 placentas collected from a prospective cohort had digital photographs of the chorionic plate. Of these, 1023 were term, 44 had velamentous cord insertion and 12 had missing clinical data, leaving N=967 (94.5 %) cases for analysis. Mathematical tools included a dynamical stochastic growth model of placental vasculature, Fourier analysis of radial parameterization of placental perimeters, and relative chorionic vascular density (a measure of "gaps" in the vascular coverage) derived from manual tracings of the fetal chorionic surface images. Bivariate correlations used Pearson's or Spearman's rank correlation as appropriate, with p<0.05 considered significant. Results:The correlation of the standard deviation of the placental radius (a measure of nonroundness of the placenta) with cord displacement was negligible (r=0.01). Empirical simulations of the vascular growth model with cord displacement showed no deviation from a normal round-tooval placental shape for cord displacement of 10 -50% of placental radius. The correlation of the metabolic scaling exponent β with cord displacement measured by Fourier analysis is 0.17 (p < 0.001). Analysis of the chorionic vascular density in traced images shows a high correlation of the © 2009 Elsevier Ltd. All rights reserved.Corresponding author: Michael Yampolsky, PhD Department of Mathematics University of Toronto 40 St. George Street, Toronto, Canada M5S2E4 yampolsky.michael@gmail.com. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. NIH Public Access Author ManuscriptPlacenta. Author manuscript; available in PMC 2010 December 1. Conclusion:Non-central cord insertion has little measurable correlation with placental shape in observed or simulated placentas. However, placentas with a displaced cord show a markedly reduced transport efficiency, reflected in a larger value of β and hence in a smaller birth weight for a given placental weight. Placentas with a non-central cord insertion have a sparser chorionic vascular distribution, as measured by the relative vascular distance. Even if typically a placenta with a noncentral insertion is of a normal round shape, its vasculature is less metabolically effective. These findings demonstrate another method by which altered placental structure may affect the fetal environment, influencing birth weight and potentially c...

In response to the COVID-19 pandemic, affected countries implemented various public health measures to decrease viral transmission. An unintended consequence of these measures could be hospital avoidance by patients with medical emergencies, as observed during other outbreaks in the 2000s. 1,2 Some public health messaging specifically warned groups at high cardiovascular risk, such as older people or those with heart disease, that they were at elevated risk of severe COVID-19. 3 Physical distancing may also result in loss of services and support networks, impairing patients' ability to seek medical assistance. 4 Furthermore, pandemics generate new challenges of managing personal protective equipment and cleaning protocols, 5 and additional information bottlenecks, which could result in workflow delays for emergencies like stroke. 6 Previous studies have reported declines in patients presenting to hospital with stroke or acute coronary syndrome during the pandemic. 7,8 A World Stroke Organization survey of members in several countries indicated a sharp reduction in stroke admissions by 50%-80% in the first weeks of the pandemic. 9 A crosssectional study reported a global decline in hospital admissions ResearchHealth servicesChanges in ischemic stroke presentations, management and outcomes during the first year of the COVID-19 pandemic in Alberta: a population study