Factors affecting bone turnover in premature infants are not entirely clear bu t certainly are different from those influencing bones of adults and children. T o identify fetal and maternal factors that might influence bone turnover, we pro spectively studied 50 infants (30 preterm and 20 full-term) born at Ain Shams U niversity Obstetric Hospital in Cairo, Egypt. Maternal parity and medical histor y and infant’s weight, gestational age, gender and anthropometrical measurement s were recorded. Cord blood samples were collected and serum type I collagen C t erminal propeptide (PICP) was assessed as a marker for fetal bone formation. Fir st morning urine samples were collected and pyridinoline cross-links of collage n (Pyd) were measured as an index for bone resorption. Serum PICP was higher in premature infants when compared with full-term infants (73.30 ±15.1 versus 64. 3 ±14.7, p = 0.022) and was higher in male premature infants when compared with females (81.64 ±9.06 versus 66.0 ±15.7, p = 0.018). In a multiple regression model using PICP as the dependent variable and controlling for different infant and maternal conditions ,PICP significantly correlated with infant gender (r = 8.26 ±4.1, p = 0.05) mat ernal parity (r = -2.106 ±0.99, p = 0.041) and diabetes (r = 22.488 ±8.73, p = 0.041). Urine Pyd tended to increase in premature infants (612 ±308 versus 43 4 ±146, p = 0.057) and correlated significantly with gestational age (r = -63. 93 ±19.55, p = 0.002). Therefore, bone formation (PICP) is influenced by fetal age and gender, as well as maternal parity and diabetes. Bone resorption (Pyd) i s mostly dependent on gestational age only. Further indepth studies are needed t o enrich management of this vulnerable population. u001a Factors affecting bone turnover in premature infants are not entirely clear bu t certainly are different from those influencing bones of adults and children. T o identify fetal and maternal factors that might influence bone turnover, we pro spectively studied 50 infants (30 preterm and 20 full -term) born at Ain Shams U niversity Obstetric Hospital in Cairo, Egypt. Maternal parity and medical histor y and infant’s weight, gestational age, gender and anthropometrical measurements were recorded. Cord blood samples were collected and serum type I collagen C terminal Fir st morning urine samples were collected and pyridinoline cross-links of collage n (Pyd) were measured as an index for bone resorption. Serum PICP was higher in premature infants when compared to with full-term infants (73.30 ± 15.1 versus 64.3 ± 14.7, p = 0.022) and was higher in male premature infants when compared with females (81.64 ± 9.06 versus 66.0 15.7, p = 0.018). In a multiple regression model using PICP as the dependent variable and controlling for different infant and maternal conditions, PICP significantly correlated with infant gender (r = 8.26 ± 4.1, p = 0.05) -2.106 ± 0.99, p = 0.041) and diabetes (r = 22.488 ± 8.73, p = 0.041). Urine Pyd tended to increase in premature infants (612 ± 308 versus 43 4 ± 146, p = age (r = -63. 93 ± 19.55, p = 0.002). Bone resorption (Pyd) is influenced by fetal age and gender, as well as maternal parity and diabetes. only. Further indepth studies are needed to enrich management of this vulnerable population. u001a