Morphometric indicators of the thymus mass of fetuses and newborns of the early neonatal period

Objective: to identify reference values of thymus mass of foetuses and neonates of the early neonatal period depending on body weight. Material and methods . We analysed 922 autopsy reports of fetuses of 18-42 weeks of gestation and newborns of the first 7 days of life: group 1 - those who died of infectious diseases ( n =67); group 2 - those who died of non-infectious diseases ( n =855). Thymus mass, body weight were studied, thymic index was calculated. Spearman's criterion ( R ) was used to assess the correlation. A polynomial regression model using the Splines method was compiled. Results . We present data on thymus mass over a range of fetal and neonatal body weights from 300 to 5500 g. Thymus mass ranges from 1.1 to 1.48 g (for fetal masses of 300-500 g) to 12.36-15.09 (for neonatal masses of 400-5500 g). Organ weight increases with increasing gestational age, decreasing by the third day of newborn life. Median thymic index values for groups 1 and 2 were 0.32 and 0.28 ( p =0.2). Regardless of the type of pathology, gestational age, and life expectancy, thymus mass correlated with body weight ( R =0.88; p 2-75.662 x +104.47 for children of group 1 and y =16.65 x 2-93.487 x +133.56 for group 2. Reference values of thymus mass of foetuses and neonates of the early neonatal period depending on body weight are presented: it was found that there is a direct strong correlation between thymus mass and body weight.