Maternal-administered physical activity enhances bone mineral acquisition in premature very low birth weight infants

Objective: To determine if physical activity delivered by an infant's mother would be as effective in promoting bone mineral acquisition in preterm very low birth weight (VLBW) infants as the same intervention administered by a trained therapist. Patients and methods: Preterm VLBW infants were randomized to receive daily physical activity administered by the infant's mother (MOM, n =11) or a trained therapist (OT, n =11), or control ( n =11). Physical activity consisted of range of motion movements against passive resistance to all extremities for 5 to 10 min daily. All infants were fed mother's milk with fortification to 24 kcal oz −1 . Dual energy x-ray of the forearm bone area (BA, cm 2 ), mineral content (BMC, g), and density (BMD, g/cm 2 ) and measurement of bone formation (bone-specific alkaline phosphatase, BAP) and resorption (urine pyridinium crosslinks of collagen, Pyd) were obtained at study entry and at 2.0 kg of body weight. Result: Forearm BA and BMC gains were greater in MOM and OT infants compared to the control infants despite similar postnatal growth rate and nutrient intake. Serum BAP levels decreased in controls but remained unchanged in MOM and OT infants. Urine Pyd levels were similar at baseline to 2.0 kg for all groups. These findings suggest greater bone growth and mineral acquisition in MOM and OT infants than control infants. Conclusion: This study demonstrates that a physical activity program administered by the infant's own mother is as equally effective as therapist-administered physical activity in promoting greater bone growth and mineral acquisition in preterm VLBW infants.