To determine the gene profile associated with changes in the cardiac structure of HF-fed postpartum mice, we quantified mRNA abundance of genes regulating fibrosis, extracellular matrix (ECM) remodeling, cardiac hypertrophy, angiogenesis, estrogen receptors, and the renin-angiotensin system using NanoString nCounter gene expression analysis in the left ventricles of nulliparous and postpartum mice after 20 weeks of diet feeding. The gene discussed is ESR1; the disease is hydrops fetalis.