The liver is the largest internal organ in humans and provides multiple functions including bile production, metabolism and detoxification of xenobiotic compounds, glycogen storage, glucose regulation, and production of serum proteins (e.g. albumin, fibrinogen). In adults, the liver is primarily comprised of hepatocytes (70–80% liver mass). However, during prenatal development, the liver serves as the primary site of hematopoiesis and is comprised of hematopoietic stem cells as well as hepatic progenitor cells. Human fetal liver is generally accepted to have limited capacity for the metabolism of xenobiotics. However, some enzymes show preferential expression in fetal liver versus postnatal liver as exemplified by CYP3A7. The objective of this study was to further understand differences in prenatal versus pediatric liver functions utilizing whole‐genome transcriptome analyses. RNA‐seq was performed on 10 prenatal (14.7–16.4 weeks EGA) and 52 pediatric human liver samples that were separated into 4 groups by age (<1 year; 1–<6 years; 6–<12 years; and 12–18 years). Comparisons of differential gene expression between two adjacent age groups were made for transcripts that were expressed in 5 or more samples. Overall, 20355 transcripts were differentially expressed in prenatal or pediatric liver samples of which 9507 (46.7%) transcripts exhibited consistent expression across age groups. The largest number of gene expression changes (13.2% of genes) were observed between prenatal and pediatric liver samples from children <1year of age with 2084 and 606 genes decreasing or increasing between these two groups, respectively. As expected, drug/xenobiotic metabolizing enzymes were among genes differentially expressed between prenatal and postnatal liver including FMO1, ALDH3B1, members of the GST family (GSTA4, GSTP1, GSTO2, HPGDS), and MGST3 that are expressed higher in prenatal liver versus postnatal liver (corrected p<0.05). Pathway analysis with Ingenuity reveals that the top gene network with decreasing expression is DNA Replication, Recombination, and Repair, Cell Cycle, Developmental Disorder, and is typified by the expression of TGFB1 (score=37). The top network with increased expression is Cellular Function and Maintenance, Inflammatory Response, Cellular Development (score=36) and is typified by the gene encoding the glucocorticoid receptor. Global changes in gene expression, including for genes associated with xenobiotic metabolism, are likely due to changes in the function of the liver during the transition from the in utero environment.