Abstract 155

AIMS: To determine the concentration of fetal markers of bone formation and resorption in amniotic fluid of normal pregnancies and of pregnancies complicated by intrauterine growth retardation and maternal diabetes.

MATERIALS: Two hundred and one amniotic fluid samples obtained by amniocentesis at 14 to 40 weeks' gestation.

MEASUREMENTS: We determined amniotic fluid concentrations of carboxyterminal propeptide of type I procollagen (PICP, index of bone formation) and cross-linked carboxyterminal telopeptide of type I collagen (ICTP, index of bone resorption) in normal pregnancies and in pregnancies complicated by fetal growth retardation and maternal diabetes.

RESULTS: Both PICP and ICTP concentrations in amniotic fluid were inversely associated with gestational age (p<0.0001). Amniotic fluid concentrations of PICP differed as a function of intrauterine growth. Small for gestational age had significantly lower amniotic fluid PICP concentrations than controls (p=0.045). In this study maternal diabetes had no influence on fetal indices of bone turnover.

CONCLUSIONS: Fetal bone turnover, as assessed by biochemical indices, appears to decrease with increasing gestational age. Intrauterine growth retardation is associated with biochemical evidence of decrease bone formation.