The Regulation of Apoptosis in Intrauterine Growth Restriction: A Study of Bcl-2 and Bax Gene Expression in Human Placenta

Abstract

Introduction: In this study, we assessed Bcl-2 and Bax gene expression patterns in human placental samples from intrauterine growth restriction (IUGR) pregnancies using normal pregnancy as control. We hypothesized that either or both of these regulatory genes are involved in the enhanced apoptotic activity known to occur in IUGR. Materials and Methods: We compared Bcl-2 and Bax gene expression in placental samples from all IUGR pregnancies treated in our clinic between January 1, 2010 – January 1, 2011 versus 140 normal pregnancy samples from the same study period. We also assessed clinical parameters such as maternal age, gestational weight gain, gestational BMI change, and maternal birth weight. Results: In IUGR, the Bcl-2 gene was underexpressed compared to normal pregnancy. There was no difference in the Bax gene activity in the two groups. The degree of growth restriction within the IUGR group did not correlate with Bcl-2 or Bax gene activity. The risk for IUGR appeared highest with maternal age between 17-24 and 35-44. Discussion: Our study revealed that it is the reduced inhibitory activity of the Bcl-2 gene rather than an enhanced stimulatory activity of the Bax gene in the background of the increased apoptosis observed in IUGR. IUGR appears to be more common with maternal age around 20 years and above 35 years. Gestational weight gain and gestational BMI change also predict the risk for IUGR.