3RD TRIMESTER FETAL GROWTH AND UMBILICAL VENOUS-BLOOD CONCENTRATIONS OF IGF-1, IGFBP-1, AND GROWTH-HORMONE AT TERM

Insulin-like growth factor-1 (IGF-1), insulin-like growth factor bindi ng protein-1 (IGFBP-1) and growth hormone (GH) concentrations were mea sured in umbilical venous blood after delivery of 78 term newborn infa nts. Three groups of pregnancies were prospectively identified during the third trimester, according to fetal size and subsequent fetal grow th, assessed by repeated ultrasound scans. Fetal size was considered e ither appropriate for gestational age (AGA) or small for gestational a ge (SGA), according to whether the first ultrasound measurement of abd ominal circumference was equal to or above, or below the tenth centile for gestational age, respectively. Subsequent fetal growth was quanti fied by the change in the standard deviation score of abdominal circum ference measurements between the first and last scans before delivery. Fetal growth retardation (FGR) was defined as a (negative) change in SD score of greater than -1.5. Eighteen SGA fetuses with evidence of F GR had significantly lower IGF-1 (median 0.05 (range 0.0-0.24) U/ml) a t delivery than 35 SGA fetuses with normal growth (median 0.13 (range 0.0-0.94) U/ml; P < 0.05) and 25 AGA fetuses with normal growth (media n 0.31 (range 0.0-0.84) U/ml; P < 0.05). The median concentration in t he SGA group with normal growth was also significantly lower than that of the AGA group with normal growth. There were no significant differ ences in IGFBP-1 or GH concentrations between the three groups. These observations indicate that umbilical blood concentrations at birth of IGF-1, but not IGFBP-1 or GH, relate to both fetal size and fetal grow th during the third trimester of pregnancies reaching term.