Amniotic fluid C-peptide as an index for intrauterine fetal growth

Abstract

Amniotic fluid C-peptide (AFCP) was monitored as an indicator of the amount of insulin secreted by the fetus in utero. Levels of amniotic fluid and cord blood C-peptide, insulin, and glucose were measured in 103 nondiabetic infants at ≥36 weeks' gestation. Infants were grouped according to birth weight and gestational age at delivery, as follows: small for gestational age (SGA, ≤10%, n = 11), average for gestational age (AGA, 10% to 90%, n = 75), large for gestational age (LGA, >90%, n = 17). AFCP correlated best with infant weight-gestational age percentile classification: low AFCP in SGA infants and high AFCP in LGA infants. The data from this study suggest that a persistently low production of insulin by SGA fetuses and a high production of insulin by LGA fetuses may lead to the different intrauterine growth rates observed.