title: Cord serum prolactin in relation to the time of the day, the sex of the neonate and the birth weight.
abstract: Serum prolactin was measured in 581 blood samples collected immediately after birth from 563 single new-born and from 9 pairs of twins. Cord serum prolactin is high at birth: the mean level is some 5 times higher than in adults. There is no sex difference in cord serum prolactin concentration in the neonate. Mean serum prolactin is significantly higher at 1.00 and 2.00 a.m. Thus a circadian periodicity in serum prolactin concentration seems to appear already during foetal life well before the organization of sleep rhythm. Cord serum prolactin increases with birth weight ranging from 1500 g to 3500 g. Thus, the control of levels of circulating prolactin changes during foetal life resulting in a progressive increase starting from mid-pregnancy. Mean cord serum prolactin at birth is lower in twins than in single new-borns. There is no significant difference in serum prolactin between the first and the second twin.
mesh_terms: D001724:Birth Weight; D002940:Circadian Rhythm; D005260:Female; D005312:Fetal Blood / Q000032:analysis*; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D011247:Pregnancy; D011388:Prolactin / Q000097:blood*; D012737:Sex Factors; D014427:Twins
chemical_list: D011388:Prolactin