Pregnancy requires the coordination of metabolically active organs to support maternal nutrition and fetal growth. However, the metabolic cross-talk between adipose tissue and liver in females during pregnancy is still less clear. In this study, we evaluated the metabolic adaptations and phenotypes of liver in response to pregnancy-associated metabolic stress, particularly in the context of genetic ablation of Uncoupling protein 1 (Ucp1)-mediated catabolic circuit. Our results revealed that Ucp1 deficiency (UCP1 knockout, KO) mice during late pregnancy exhibited significantly deteriorated metabolic phenotypes, including hepatic steatosis and whole-body glucose and lipid homeostasis, as compared to Ucp1 deficiency or normal pregnancy mice. However, non-pregnant Ucp1 deficiency mice displayed nearly normal metabolic phenotypes and structure alterations similar to those of littermate controls. Moreover, transcriptomic analyses by RNA sequencing (RNA-seq) clearly revealed that Ucp1 deficiency led to a significant liver metabolic remodeling of differentially express genes (DEGs) before and especially during pregnancy. Consistently, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses demonstrated the potential altered functions and signaling pathways, including metabolic dysfunctions in ribosome, oxidative phosphorylation, etc. Importantly, as derived from trend analyses of DEGs, our results further revealed the distinct expression pattern of each subcluster, which coincided with potential biological functions and relevant signaling pathways. The findings in the present study might provide valuable insights into the molecular mechanism of metabolic dysfunction-associated fatty liver disease (MAFLD) during pregnancy. Additionally, our data may provide a novel animal model of MAFLD, thus facilitating its potential therapies. NEW & NOTEWORTHY: Genetic ablation of Ucp1 during pregnancy increases hepatic steatosis and deteriorated whole-body glucose and lipid homeostasis. Moreover, changes in hepatic gene expression are closely associated with metabolic dysfunctions in ribosome and oxidative phosphorylation. This work highlights the therapeutic potential of targeting UCP1- mediated catabolic circuit between adipose and liver during pregnancy, and the utility of RNA-seq analysis to reveal valuable information for the distinct expression pattern of each subcluster that contribute to pregnancy-dependent MASLD progression.Copyright © 2025 Elsevier Inc. All rights reserved.