PREMATURITY AND RICKETS

Abstract

Sixty-nine premature infants receiving different dietaries and with birth weights below 2,000 gm were studied with chemical, clinical and radiologic methods. Vitamin D was given to all infants from the age of 4 days. The concentrations of calcium, phosphorus and phosphatase in the serum showed variations toward those seen in active rickets. These changes were somewhat more marked in infants fed human milk than cow's milk. Supplementation of human milk with dried skimmed cow's milk did not significantly alter these changes. Craniotabes was more frequently seen in premature infants fed human milk than cow's milk. Otherwise, no clinical signs of rickets were found. All the premature infants were born with a metaphyseal zone of rarefaction. These zones are believed to be the result of a disturbance in ossification which occured during the last weeks of pregnancy, perhaps caused by a factor which was also responsible for the premature birth. They gradually merge with the general osteoporosis developing 10 to 13 weeks after birth. Later, periosteal double contours are visible. These double contours are the first signs of an improved mineralization. There was no correlation between abnormal chemical findings and the most conspicuous radiologic or clinical findings. No case of recognizable rickets was observed among the infants studied. This risk of rickets, despite an adequate supply of vitamin D, is probably not as great as stated by previous investigators, and is probably the same whether the infants are fed human milk or cow's milk.