Tissue specific DNA methylation is present across many genomic elements, including large genomic regions. Most human tissues posses highly methylated genomes (>70%), but recent data has suggested the presence of partially methylated domains (PMDs) in some cell-lines. Placenta is a unique human tissue which has very different molecular properties than most tissues. It is the aim of this study to identify the presence/absence of PMDs in placental tissue and further define the DNA methylation landscape of the placenta. In particular this experiment is designed to look at the placental methylome across gestational ages in chromosome 21 to detect methylomic differences throughout development.