Fetal Bone Loading Is a Critical Determinant of Fetal and Young Infant Bone Strength

Background: The Utah Paradigm is the contemporary model of bone physiology that allows for an understanding of risk factors for bone fragility and can be used in understanding infants who present with multiple unexplained fractures in contested cases of child abuse. Method: The Utah Paradigm was applied to the fetal period in over 500 cases of contested child abuse cases in infants with multiple unexplained fractures to determine if risk factors for bone fragility could be identified. Findings: Multiple risk factors for fetal bone fragility were identified: inadequate provision by the mother during pregnancy of essential bone nutrients (calcium, phosphate, vitamin D, and protein), prematurity, gestational diabetes, and fetal exposure to drugs that can affect bone strength. The most common risk factor was decreased fetal bone loading from decreased fetal movement. More than one risk factor was often identified in these cases, and the term Metabolic Bone Disease of Infancy is used to describe this multifactorial bone fragility disorder of young infants. Infants with Metabolic Bone Disease of Infancy have X-rays that show poor bone mineralization, and this condition can be misdiagnosed as child abuse. Interpretation: Metabolic Bone Disease of Infancy should be considered in infants with multiple unexplained fractures. This condition can be established by finding abnormal X-rays showing poor bone mineralization and risk factors for bone fragility. Fetal bone loading is the most critical determinant of fetal and young infant bone strength. Situations that cause decreased fetal movement can casue decreased fetal and young infant bone strength.