Maternal levels of free fetal DNA are elevated in pregnancies with growth restriction due to placental dysfunction

Abstract

Objective. Fetal growth restriction (FGR) is associated with an increased risk of perinatal mortality and morbidity
but can have many different causes. Non-cellular fetal DNA in maternal blood offers many opportunities for noninvasive
prenatal diagnosis. It is likely that the source of the DNA is apoptosis or cell death in the placenta
and that free fetal DNA (ffDNA) levels could theoretically be increased in placental dysfunction or infarction.
We hypothesised that non-cellular fetal DNA levels would be increased only in the subset of FGR cases with
placental dysfunction, which could explain previous contradictory reports.
Methods. We used plasma samples obtained during a previous study from pregnant women with singleton male
pregnancies as controls and from women with small-for-gestational-age (SGA) infants that had been classified as
having FGR due to placental dysfunction. A third group was defined as normal but small fetuses with placental
function within the normal ranges indicated by Doppler studies. Twenty-two cases were identified in the third
trimester of pregnancy (8 from the control group and 7 from each of the FGR and the normal small groups). DNA
was extracted and the DYS14 gene of the Y chromosome was quantified by real-time quantitative polymerase
chain reaction (PCR).
Results. ffDNA levels were higher in pregnancies with FGR due to placental dysfunction than in either normal
pregnancies or those with SGA fetuses from causes other than placental dysfunction. There was no significant
difference in the ffDNA levels between the fetuses of normal growth and those with FGR from other causes.
Conclusion. The level of ffDNA in maternal plasma is increased in pregnancies complicated by FGR secondary
to placental dysfunction but not in those with small fetuses with normal placental function.

South African Journal of Obstetrics and Gynaecology Vol. 13 (2) 2007: pp. 60-63