Maternal Phenylketonuria (MPKU) is a condition that affects pregnant women who have inherited Phenylketonuria (PKU), an inherited metabolic disorder. PKU prevents the body from properly breaking down the amino acid phenylalanine, leading to a buildup of this substance in the blood. MPKU refers to the impact of PKU on a developing fetus during pregnancy. Synonyms for MPKU include Maternal PKU, Maternal Hyperphenylalaninemia, and Maternal Phenylalanine Hydroxylase Deficiency. These terms describe the same condition of an expectant mother with PKU and highlight the risk of elevated phenylalanine levels affecting the developing baby. Early diagnosis and dietary management are crucial to prevent complications and ensure a healthy pregnancy.