CELL-DIVISION IN PLACENTAS OF APPROPRIATE AND SMALL-FOR-GESTATIONAL-AGE INFANTS - A FLOW-CYTOMETRY STUDY

Background. The purpose of this study was to examine if placentas of s mall- for-gestational-age (SGA) and non-SGA infants differ with respec t to proliferative cell activity. Method. Cell cycle distribution was studied in placentas from 181 SGA (birthweight <10th percentile) and 5 28 non-SGA births by flow cytometry measurements of relative DNA conte nt. Results. The fraction of cells in various cell cycle phases (G(1)- , S- and G(2)-phases) did not differ with gestational age from 30 to 4 3 weeks in either of the groups. The placentas of the SGA infants had a significantly lower mean (+/-1 SEM) growth fraction than placentas o f non-SGA infants (S-phase 5.2 +/- 0.2 vs 5.5 +/- 0.1, p = 0.05, and G (2)-fraction 5.4 +/- 0.2 vs 6.3 +/- 0.1, p < 0.001), but the overlaps of the distributions were large. Thus sensitivity, specificity and pre dictive values of low fractions did not differ substantially from a pu rely random prediction of SGA. Conclusions. Cell division in the place nta is maintained until and beyond term. Placentas of SGA infants have , on average, lower proliferative activity than placentas of non-SGA i nfants, but the difference is too small to be of predictive value in i dentifying intrauterine growth retardation.