During foetal life, maximum growth is caused by
a. Thyroid is the first endocrine gland to develop in the fetus around the 4th post conceptional week, the pancreas develops as outgrowth of the duodenal endoderm and insulin secretion has been observed by 12 weeks.
b. Fetal growth has been divided in to three consecutive cell growth phases, the initial phase of hyperplasia occurs during the first 16 weeks and is characterized by a rapid increase in cell number. The second phase, which extends up to 32 weeks includes both cellular and hypertrophy, After 32 weeks the fetal growth occurs via cellular hypertrophy and it is during this phase that most fetal fate an glycogen deposition takes place.
c. The corresponding fetal growth rates during these three cell growth phases are from 5g/day at 15 weeks, 15-20 g/day at 24 weeks, and 30-35 g/day at 34 weeks
d. There is considerable evidence that insulin and insulin like growth factor IGF-I and IGF-II, have a role in the regulation of fetal growth and weight gain