Polymorphic imprinted methylation in the human placenta. (A) DNA methylation shows a polymorphic pattern across known (orange) and novel (blue) DMRs among 63 placental samples from 1st (N = 5, black), 2nd (N = 9, light gray), and 3rd (N = 49, dark gray) trimester samples. The color scale was set to show those samples that deviate from the intermediate range of methylation. (B) Mean standard deviation across all DMRs (N = 144) is shown for placenta, fetal somatic tissues, and adult whole blood (P < 2.2 × 10⁻¹⁶, Kruskal–Wallis). Y-axis is on a logarithmic scale.