Growth rate of thyroid gland in human fetus

Objectives to determine the thyroid gland growth rate in the intermediate fetal period of human ontogenesis. Material and methods. The thyroid glands of 60 male and female fetuses aged from 14 to 27 weeks were the subject of this research. The material was divided according to fetus age in three groups: Group I from 14 to 18 weeks, Group II from 19 to 22 weeks and Group III from 23 to 27 weeks. Results. The study revealed the increase in all dimensions of thyroid gland related to the increase of fetus age. During the intermediate fetal period of ontogenesis, the growth varied from 19% (for the anteroposterior isthmus size) to 59% (for the right lobe height). The thyroid gland growth rate for different sex groups varied between 24% and 60% in female fetuses, in male fetuses from 20% to 57%. Besides, the thyroid lobes and isthmus of female fetuses grew at a higher rate than those of the male fetuses. The uneven growth of the anatomical structure was also registered when comparing different age groups within the intermediate fetal period. The highest rate of thyroid gland growth was observed starting from the 22nd week of fetal life; until the 19th week the growth rate ranged between 7% (isthmus) and 25% (right lobe). The study of the thyroid gland growth rate in female and male fetuses in different age groups revealed identical tendencies involving the active growth of thyroid gland dimensions starting from the 22nd week.