Human adipogenic serum activity increases during pregnancy.

Adipogenic factor required for adipose differentiation of 3T3-F442A cells is present in human serum. Its activity increases significantly 3-4 fold in maternal serum after the 25th-28th weeks of pregnancy. It remains high until parturition and it is also found at high levels in serum from umbilical cord blood, whereas amniotic fluid from late gestation ages has a very low adipogenic activity. Adipogenic activity from maternal serum decreases abruptly one day after parturition and it reaches normal levels similar to those found in non-pregnant women, remaining constant thereafter. It is suggested that adipogenic serum activity could have some significance for human adipose tissue differentiation.