Pilot study of comparative placental morphometry in pre-eclamptic and normotensive pregnancies suggests possible maladaptations of the fetal component of the placenta

Abstract

Objective: Adequate maternal, intervillous and fetal blood flow are all necessary for fetal well-being. Compromise to any part of this exchange would be detrimental to pregnancy outcome. Pre-eclampsia is associated with reduced maternal spiral artery flow, resulting in reduced placental perfusion. This in turn creates an ischaemic environment, which may predispose to morphological changes in placental villi. This pilot study sought to assess whether there were morphological alterations in the fetal component of the placenta which could be detrimental to exchange and therefore pregnancy outcome.

Study design: This study utilized morphometric image analysis to examine some features of the fetal component of the placenta in normotensive (NT) and pre-eclamptic (PE) groups. The features examined included: density of placental villi (expressed as percentage of field area occupied by placental tissue); stem vessel carrying capacity (expressed as percentage of stem villus area occupied by vessel lumina); the thickness of the stem arterial walls relative to artery size (expressed as percentage of artery area occupied by arterial wall) and the extent of fibrosis associated with villi (expressed as percentage of field area occupied by fibrosis).

Results: There were significant differences between NT and PE placentae in density of placental villus arrangement NT: 51.89 ± 6.19, PE: 64.78 ± 6.93 (P<0.001); carrying capacity of stem villi NT: 17.20 ± 11.78, PE: 8.67 ± 8.51 (P<0.001); relative thickness of stem villi arterial walls NT: 74.08 ± 12.92, PE: 86.85 ± 10.55 (P<0.001); and extent of fibrosis NT: 0.727 ± 0.310, PE: 1.582 ± 0.707 (P<0.001).

Conclusion: These significant differences between normotensive and pre-eclamptic placentae suggest possible fetal maladaptations in response to the intervillous ischaemia, compounding the existing maternal compromise to materno-fetal exchange. Further investigations would, however, be necessary in order to make more conclusive deductions.