• Any abnormality, anatomical or biochemical, evident at birth or during the neonatal period.
  NCI
  U.S. National Cancer Institute, 2021
• (congenital malformation) A morphologic defect of an organ, part of an organ, or larger region of the body that results from an intrinsically abnormal developmental process during gestation.
  NICHD Pediatric Terminology
  U.S. National Cancer Institute, 2021
• (congenital abnormalities) Malformations of organs or body parts during development in utero.
  NLM Medical Subject Headings
  U.S. National Library of Medicine, 2025
• (congenital defect/deformity) Any abnormality either hereditary or due an influence that happen during the pregnancy until the moment of birth.
  U.S. FDA Glossary
  U.S. Food & Drug Administration, 2021
• Birth defects, also called congenital anomalies, are physical abnormalities that occur before a baby is born. They are usually obvious within the first year of life. The cause of many birth defects is unknown, but infections, genetics, and certain environmental factors increase the risk.
  Merck Manuals
  Merck & Co., Inc., 2025
• Malformation, in biology, irregular or abnormal structural development. Malformations occur in both plants and animals and have a number of causes. The processes of development are regulated in such a way that few malformed organisms are found. Those that do appear may, when properly studied, shed...
  Encyclopedia Britannica
  Encyclopedia Britannica, Inc., 2025