AMNIOTIC FLUID (AF) ARGINIE-VASOPRESSIN (AVP) CONCENTRATIONS IN NORMAL PREGNANCIES AND INTRAUTERINE GROWTH RETARDATION (IOGR)

Abstract

AVP is released by the fetus but only in response to osmotic, but also to nonosmotic stimuli such as hypoxia. Once released, AVP is excreted via fetal urine into AF where it has a long half life compared to plasma (ca 8 hours). Tbe hypothesis of the present study therefore was, that fetal hypoxia might be diagnosed by elevated AF-AVP levels. As a model we used IUGR fetuses which are known to he hypoxic. 25 infants entered the study because IUGR was suspected by ultrasound. The normal AF-AVP levls as control values were determined in 93 uncomplicated pregnancies where amniocentesis was performed for other reasons (L/S ratio determinations, genetic reasons, rh-sensitized pregnancies with rh-negative fetuses). HPL values were measured by RIA as were Af-AVP values. Results: The mean AF-AVP levels in normal pregnancies from 16 to 41 weeks of gestation was 2.37 ± 1.16 SD pg/ml. There was no significant difference with different gestational age. At birth 7 of the 25 infants hod normal birth weight and 18 actually had IUGR. There was a significant correlation between the degree of IUGR and AF-AVP levels (r=.59, p<0.05). The correlation between the HPL values and the degree of IUGR was the same as for AF-AVP values (r=.59, p<0.05). Discussion: 1) To our knowledge we report AF-AVP values for the greatest group of normal pregnancies yet published. 2) AF-AVP levels are elevated in IUGR. Ihe levels dependent on the severity of IUGR. These data support the usefulness of AF-AVP determinations for the diagnosis of fetal wellbeing as demonstrated in a previous study in rh-erythroblastosis (1). The elevated AF-AVP levels in IUCR might explain findings of diminished urine production of these fetuses (2). (1)Stegner et al. Acta Endocrinol 112,267,1986 (2)Wallenburg et al. J Perinot Med 6,233,1977