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 small- for-gestational-age (SGA) and non-SGA infants differ with respect to proliferative cell activity.

METHOD

Cell cycle distribution was studied in placentas from 181 SGA (birthweight < 10th percentile) and 528 non-SGA births by flow cytometry measurements of relative DNA content.

RESULTS

The fraction of cells in various cell cycle phases (G1-, S- and G2-phases) did not differ with gestational age from 30 to 43 weeks in either of the groups. The placentas of the SGA infants had a significantly lower mean (+/-1 SEM) growth fraction than placentas of non-SGA infants (S-phase 5.2 +/- 0.2 vs 5.5 +/- 0.1, p = 0.05, and G2-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 predictive values of low fractions did not differ substantially-from a purely random prediction of SGA.

CONCLUSIONS

Cell division in the placenta is maintained until and beyond term. Placentas of SGA infants have on average, lower proliferative activity than placentas of non-SGA infants, but the difference is too small to be of predictive value in identifying intrauterine growth retardation.