کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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2789022 | 1154465 | 2013 | 4 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Probability distributions of placental morphological measurements and origins of variability of placental shapes Probability distributions of placental morphological measurements and origins of variability of placental shapes](/preview/png/2789022.png)
IntroductionWhile the mean shape of human placenta is round [1] with centrally inserted umbilical cord, significant deviations from this ideal are fairly common, and may be clinically meaningful [1]. Traditionally, they are explained by trophotropism. We have proposed a hypothesis explaining typical variations in placental shape by randomly determined fluctuations in the growth process of the vascular tree. It has been recently reported that umbilical cord displacement in a birth cohort has a log-normal probability distribution, which indicates that the displacement between an initial point of origin and the centroid of the mature shape is a result of accumulation of random fluctuations of the dynamic growth of the placenta. To confirm this, we investigate statistical distributions of other features of placental morphology.MethodsIn a cohort of 1023 births at term digital photographs of placentas were recorded at delivery. Excluding cases with velamentous cord insertion, or missing clinical data left 1001 (97.8%) for which placental surface morphology features were measured. Best-fit statistical distributions for them were obtained using EasyFit.Results and discussionThe best-fit distributions of umbilical cord displacement, placental disk diameter, area, perimeter, and maximal radius calculated from the cord insertion point are of heavy-tailed type, similar in shape to log-normal distributions. This is consistent with a stochastic origin of deviations of placental shape from normal.ConclusionsDeviations of placental shape descriptors from average have heavy-tailed distributions similar in shape to log-normal. This evidence points away from trophotropism, and towards a spontaneous stochastic evolution of the variants of placental surface shape features.
Journal: Placenta - Volume 34, Issue 6, June 2013, Pages 493–496