Placental measurements and their association with birth weight in a Brazilian cohort.

INTRODUCTION: Epidemiological studies have shown associations between placental measurements and perinatal and later life outcomes. OBJECTIVES: To report placental measurements and evaluate their association with birth weight in a Brazilian birth cohort. METHODS: Retrospective cohort study with 958 mothers, placentas, and newborns delivered at the Ribeirão Preto Medical School Hospital, Universidade de São Paulo, Brazil, in 2010 and 2011. The information was collected from interviews, medical records, and pathology reports. The placental measurements were: weight, largest and smallest diameters, eccentricity, thickness, shape, area, and birth weight/placental weight and placental weight/birth weight ratios. We analyzed the associations between birth weight and placental measurements using multiple linear regression. RESULTS: Placental weight alone accounted for 48% of birth weight variability (p < 0.001), whereas placental measurements combined (placental weight, largest and smallest diameters, and thickness) were responsible for 50% (p < 0.001). When adjusted for maternal and neonatal characteristics, placental measurements explained 74% of birth weight variability (p < 0.001). CONCLUSION: Placental measurements are powerful independent predictors of birth weight. Placental weight is the most predictive of them, followed by the smallest diameter.

Placental measurements and their association with birth weight in a Brazilian cohort / Medidas placentárias e sua associação com o peso ao nascer em uma coorte brasileira

ABSTRACT: Introduction: Epidemiological studies have shown associations between placental measurements and perinatal and later life outcomes. Objectives: To report placental measurements and evaluate their association with birth weight in a Brazilian birth cohort. Methods: Retrospective cohort study with 958 mothers, placentas, and newborns delivered at the Ribeirão Preto Medical School Hospital, Universidade de São Paulo, Brazil, in 2010 and 2011. The information was collected from interviews, medical records, and pathology reports. The placental measurements were: weight, largest and smallest diameters, eccentricity, thickness, shape, area, and birth weight/placental weight and placental weight/birth weight ratios. We analyzed the associations between birth weight and placental measurements using multiple linear regression. Results: Placental weight alone accounted for 48% of birth weight variability (p < 0.001), whereas placental measurements combined (placental weight, largest and smallest diameters, and thickness) were responsible for 50% (p < 0.001). When adjusted for maternal and neonatal characteristics, placental measurements explained 74% of birth weight variability (p < 0.001). Conclusion: Placental measurements are powerful independent predictors of birth weight. Placental weight is the most predictive of them, followed by the smallest diameter.

RESUMO: Introdução: Estudos epidemiológicos demonstraram associações entre medidas placentárias, resultados perinatais e futuros. Objetivos: Descrever medidas placentárias e avaliar suas associações com peso ao nascer numa coorte de nascimentos brasileira. Metodologia: Estudo de coorte retrospectiva de 958 mães, placentas e recém-nascidos no Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo, Brasil, em 2010 e 2011. As informações foram coletadas por entrevistas, prontuários médicos e laudos de patologia. As medidas placentárias foram: peso, diâmetros maior e menor, excentricidade, espessura, forma, área, relações peso ao nascer/ peso da placenta e peso da placenta/ peso ao nascer. As associações entre peso ao nascer e medidas placentárias foram examinadas por meio de regressão linear múltipla. Resultados: O peso da placenta foi responsável por 48% da variabilidade do peso ao nascer (p < 0,001), enquanto o conjunto de medidas placentárias (peso, diâmetros maior e menor e espessura) foi responsável por 50% (p < 0,001). Quando ajustadas pelas características maternas e neonatais, as medidas placentárias explicaram 74% da variabilidade do peso ao nascer (p < 0,001). Conclusão: medidas placentárias são preditores independentes do peso ao nascer. O peso placentário é o mais forte preditor dentre elas, seguido pelo diâmetro menor.

Placental morphometry in hypertensive disorders of pregnancy and its relationship with birth weight in a Latin American population.

OBJECTIVE: To assess the placental morphometry in pregnancies with hypertensive disorders of pregnancy (HDP) and its relationship with birth weight (BW). STUDY DESIGN: Cohort study of placental morphometry and fetal outcomes of 954 pregnancies at a university hospital in Ribeirão Preto, São Paulo, Brazil, in 2010. HDP categories were: chronic (CH), gestational (GH), preeclampsia (PRE) and pre-eclampsia superimposed on chronic hypertension (CH + PRE). Associations between BW and placental measures (PM) in pregnancies were evaluated by multiple linear regression analyses. MAIN OUTCOME MEASURES (PM): Placental weight (PW, g), largest and smallest diameters (cm), thickness (cm), eccentricity, area (cm2), volume (cm3), BW/PW ratio and PW/BW ratio (efficiency). RESULTS: The frequencies of each HDP categories were 6.5% CH; 7.6% GH; 6.1% PRE, and 2.0% CH + PRE. PW, largest and smallest diameters, area and BW/PW ratio were statistically different between HDP and the normotensive group, with the lowest values for CH + PRE; the remaining measures showed no difference. BW was lower in HDP than in the normotensive group (p = 0.016). BW and PW were highly correlated in the presence of HDP (r = 0.79, p < 0.001). Sixty-seven percent of BW variability was accounted for PM (p < 0.001), and increased to 81% when maternal variables, gestational age and sex were added (p < 0.001). CONCLUSIONS: Hypertensive disorders of pregnancy significantly influence the growth of both the placenta and the fetus. PM explain 67% of BW variability, and CH + PRE was the category with the strongest association to the results.