Use of a Bayesian hierarchical model to study the allometric scaling of the fetoplacental weight ratio

Fidel Ernesto Castro Morales,Anna Cecília Queiroz De Medeiros

doi:10.1590/1806-93042016000100008

Abstract

Abstract Objectives: to propose the use of a Bayesian hierarchical model to study the allometric scaling of the fetoplacental weight ratio, including possible confounders. Methods: data from 26 singleton pregnancies with gestational age at birth between 37 and 42 weeks were analyzed. The placentas were collected immediately after delivery and stored under refrigeration until the time of analysis, which occurred within up to 12 hours. Maternal data were collected from medical records. A Bayesian hierarchical model was proposed and Markov chain Monte Carlo simulation methods were used to obtain samples from distribution a posteriori. Results: the model developed showed a reasonable fit, even allowing for the incorporation of variables and a priori information on the parameters used. Conclusions: new variables can be added to the modelfrom the available code, allowing many possibilities for data analysis and indicating the potential for use in research on the subject.

Highlights

There is growing evidence that birth weight and placental weight may provide valuable information on the progress of gestation and/or indicate increased risk of perinatal complications.[1,2] It has been proposed that these features could be associated with the occurrence of diseases in adulthood, especially chronic non-communicable ones.[3,4]It is important to note that placental weight and birth weight are closely related
For the parameter β, a priori information distribution was provided, such that m1= 17/24, and c1=0.01, so that approximately 99% of the density distribution of β is in the range (0.5,1)
The present study aimed to use a hierarchical Bayesian model to improve the modeling of the relationship between placental weight (PP) and birthweight (PRN), based on anallometric metabolic scaling approach

Summary

Introduction

There is growing evidence that birth weight and placental weight may provide valuable information on the progress of gestation and/or indicate increased risk of perinatal complications.[1,2] It has been proposed that these features could be associated with the occurrence of diseases in adulthood, especially chronic non-communicable ones.[3,4]. It is important to note that placental weight and birth weight are closely related. It increases its ability to provide energy and nutrients required for fetal development. The efficiency of this process can be influenced by other factors, depending on the gestational context.[5]. Β is called the allometric exponent, which must necessarily be different from 1.7 The value of β is often reported to lie within the range of 3/4 to 2/3.7,8

Objectives

Methods

Results

Conclusion