Cellular proliferation in the placenta in normal human pregnancy and pregnancy complicated by intrauterine growth restriction.

Abstract

To determine the incidence of cellular proliferation in the placenta throughout the three trimesters of normal pregnancy, and in the third trimester of pregnancy complicated by intrauterine growth restriction (IUGR). Placental samples were obtained from 17 first-trimester pregnancies, 9 second-trimester pregnancies, 33 uncomplicated third-trimester pregnancies, and 21 third-trimester pregnancies complicated by IUGR. These samples were then stained by immunohistochemical technique, using the monoclonal antibody MIB-1. The incidences of cellular proliferation in the four groups were as follows: first trimester (n = 17): 11.8% of cells (8.51-17.04); second trimester (n = 9): 9.88% of cells (5.04-10.99); normal third trimester (n = 33): 3.15% of cells (2.07-3.7); IUGR third trimester (n = 21): 3.7% of cells (3.02-4.85). The decline in cellular proliferation throughout the three trimesters of pregnancy was statistically significant (P < .0001 Kruskall-Wallis test). The Spearman rank correlation for proliferative index against gestational age had a P value less than .0001 (Rho corrected for ties = -0.81). There was no statistically significant difference in the incidence of cellular proliferation between normal third-trimester and IUGR third-trimester samples. The incidence of cellular proliferation in the placenta declines as pregnancy progresses, a finding that agrees with previous work by others. The incidence of cellular proliferation was not altered in cases of IUGR.