PERINATAL ENODCRINOLOGY:LH-HCG,FSH,ESTRADIOL AND PROGESTERONE PLASMA LEVELS AND PITUITARY RESPONSIVENESS TO EXOGENOUS LH-RH DURING THE FIRST 72 HOURS OF LIFE.

Oept.of Obstetrics and Gynecology and °Clinical Biochemistry,Univer- sities of Cagliari' (Italy) and °Lausanne (Switzerland). The AA. have studi ed the behaviour pattern of LH-HCG,FSH,Estradiol(E2) and Progesterone (P) basal plasma levels in 5 groups of 9 normal new- borns of 1,6,12,24 and 72 hrs of life. Of each group 6 newborns were treated with 25 ug of LH-RH i.v. ,the other 3 were treated with saline as controls.Blood samples were taken prior to and 5,15,30 and 60 min. after the LH-RH or NaCl i.v. injections.The assays were all performed by RIA. LH-HCG basal plasma levels decreased progressively and si- gnificantly from 19,1 ~ 4,6 at 1st hr to 1,8 ~ 0,2 mU/ml at 72nd hr. FSH did not show any significant differences,ranging from 1,15 to 1,61 mU/ml,as mean values. E2 and P plasma levels decreased progressively and significantly'respectively from 17,5 ~ 3,3 (1st hr) to 0,83 ~.0,06 ng/ml (72nd hr) and from 73,3 ~ 8,9 (1st hr) to 1,24 ~ 0,42 ng/ml (72nd hr). The different age groups of newborns submitted to the LH-RH test did not show any significant variations of LH-HCG or FSH plasma levels. The small differences observed in some cases after LH-RH stimulation were of the same amplitude as those measured in the samples collected in the control group. These data sustain the existence in newborns,during the first 72 hrs of life,of a refractory peri od in the pituitary responsiveness to the exogenous synthetic LH-RH.