22 preterm infants received caffeine (starting from day 2 of life and received for more than 7 days) for apnea prophylaxis or treatment according to protocol of Ain Shams University neonatal intensive care unit [apnea prophylaxis for preterm ≤32 weeks gestation and apnea treatment for those 33 or 34 weeks gestation]. Dual Energy X-ray Absorptiometry was done 5th-6th week post-natal age

20 preterm infants for whom caffeine was not given, either it was not indicated, not available or parents refused its use.Dual Energy X-ray Absorptiometry was done 5th-6th week post-natal age

Dual Energy X-ray Absorptiometry done for both studied groups

Whole Body Scanner, Pencil beam, regions: antro-posterior Spine, Lateral, Hip, Forearm/ Hand, Ortho Femur Speed: Up To 76mm Per Sec., Scan Times (min): antro-posterior Spine-2, Lateral-12, Hip-4, Forearm-1, Femur-4 Pentium II Computer System, Windows O/S, Lunar Software 15" Hi-Resolution Monitor, Auto Centering Laser Guide, Data Analysis: Auto Analysis Software, Smart Scan, Auto Position. Weight and length were measured and recorded. During the scan an infant was placed on the scanning table with the head at the marked start line, assuring that the position was the same for all subjects. The study was carried out with the infants sleeping without sedation. The infants were placed supine and were restrained with a cotton blanket. To induce sleep, infants were fed a few minutes prior to the study. When image quality was poor due to movement of the infant or to other causes the measurement at that time point was not included for analysis.