Preterm fetal growth restriction is associated with increased parathyroid hormone–related protein expression in the fetal membranes

Abstract

Objective: Parathyroid hormone–related protein has roles in normal fetal growth, placental calcium transport, and vascular tone regulation; these factors are compromised in growth-restricted fetuses. Our objective was to determine whether intrauterine parathyroid hormone–related protein expression was increased in association with fetal growth restriction. Study Design: The expression of parathyroid hormone–related protein was examined in intrauterine tissues from women with idiopathic fetal growth restriction with preterm (n = 8-10) and term (n = 8-10) gestations and from gestation-matched control subjects. The abundance and immunoreactive content of parathyroid hormone–related protein messenger ribonucleic acid were determined by Northern blot and radioimmunoassay, respectively, in the placenta, amnion, and chorion-decidua. Results: The expression of parathyroid hormone–related protein messenger ribonucleic acid was increased in the amnion (placental and reflected) in association with preterm fetal growth restriction (P <.05). Both parathyroid hormone–related protein messenger ribonucleic acid and protein expression were increased in chorion-decidua in association with preterm fetal growth restriction (P <.05). In term gestations both parathyroid hormone–related protein messenger ribonucleic acid and protein expression were greater in amnion over placenta than in reflected amnion (P <.05); these in turn were greater than those in chorion-decidua (P <.05). No significant changes were detected in parathyroid hormone–related protein messenger ribonucleic acid or in protein expression in association with term fetal growth restriction. Conclusion: Either parathyroid hormone–related protein messenger ribonucleic acid or protein expression, or both, was increased in the fetal membranes in association with fetal growth restriction in preterm but not term gestations, suggesting that parathyroid hormone–related protein may be involved in the pathogenesis of preterm fetal growth restriction. (Am J Obstet Gynecol 2000;183:700-5.)