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

OBJECTIVE: 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). METHODS: 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 RESULTS: 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. CONCLUSION: 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. Copyright (C) 1998 by the Society for Gynecologic Investigation.