Number of variable probes increases with gestation. The number of probes with high inter-individual variation increases over gestation. Variance (s2) of each probe was calculated for each gestational age. The number of probes (y-axis; log10 scale) showing a particular level of variance (x-axis) is shown. Most probes (95% in third trimester to 98% in first trimester) show low variation (s2 < 0.009). However, there is an increase in the number of variable probes (s2 > 0.02) in third trimester placentas, and to a lesser extent second trimester placentas, compared to first trimester.
Novakovic et al. BMC Genomics 2011 12:529 doi:10.1186/1471-2164-12-529