Expression of insulin-like growth factor-I and placental growth hormone mRNA in placentas: a comparison between normal and intrauterine growth retardation pregnancies

Intrauterine growth restriction (IUGR) is generally defined as the patholog ical restriction of fetal growth resulting in a fetus with birth weight bel ow the 10th percentile for gestational age. Almost 75% of IUGR cases develo p during third trimester, Studies on animals (rodents and sheep) as well as humans suggest that insulin-like growth factor-I (IGF-I), under the influe nce of placental growth hormone (PGH) plays crucial roles in fetal growth r egulation during this period. Limited data are available with regard to IGF -I and PGH in placentae of normal and IUGR births. Therefore, in the presen t study, IGF-I and PGH mRNA expression has been studied in term placentae o f normal (n = 10) and IUGR (n = 15) births by in-situ hybridization procedu re. Their expression was also studied in first (n = 5) and second (n = 5) t rimester placentae obtained from elective termination of normal pregnancies . Both IGF-I and PGH expression were found to be higher in the first and se cond trimester placentae compared to term placentae in normal pregnancies. However, IUGR term placentae showed increased expression of both IGF-I and PGH mRNA in comparison with normal placentae. Various mechanisms leading to the increased transcription of IGF-I and PGH mRNA in IUGR placenta are dis cussed. This increased transcription perhaps occurs in response to the redu ction in the fetal growth.