The cell‐free fetal DNA fraction in maternal blood decreases after physical activity

Objective If noninvasive prenatal testing using next generation sequencing is to be effective for pregnant women, a cell-free fetal DNA (cffDNA) fraction above 4% is essential unless the depth of sequencing is increased. This study's objective is to determine whether physical activity has an effect on the proportion of cell-free DNA (cfDNA) arising from the fetus (fetal fraction). Methods Nine pregnant women carrying male fetuses at gestational age 12+0 weeks to 14+6 weeks were included. Plasma from nine pregnant women was drawn prior to, immediately after, and 30 min after 30 min of cycling with a pulse-rate of 150 beats per minute. The concentrations of cffDNA (DYS14) and cfDNA (RASSF1A) were assessed using quantitative real-time polymerase chain reaction. Results The fetal fraction decreased significantly in all participants after physical activity (p < 0.01), a decrease varying from 1–17 percentage points. This was due to a significant increase in the concentration of cfDNA (p < 0.01), whereas the concentration of cffDNA remained the same. This alteration of the fetal fraction was not present 30 min after physical activity. Conclusion When planning the timing of noninvasive prenatal diagnosis based on the fetal fraction, physical activity prior to sampling should be avoided. © 2013 John Wiley & Sons, Ltd.