Aetiological factors in rickets of prematurity.

Six very preterm (< 32 weeks' gestation) infants who developed late-onset respiratory distress were each matched for sex and gestation with 2 control preterm infants. Radiologically and biochemically the diagnosis of rickets and rachitic respiratory distress seemed clear and the pattern conformed with other reports of the syndrome. The control infants were of similar gastational ages but there was a significantly higher incidence of pre-eclampsia in the pregnancies of index cases. Also significant was a prolonged illness of several weeks' duration in the index cases; this illness was either heart failure due to patent ductus arteriosus or prolonged ventilation in the early weeks of life for apnoeic attacks. Awareness of these 2 aetiological factors shows the necessity of monitoring such infants for evidence of rickets. The use of water-soluble antirachitic prophylaxis such as 1 alpha-hydroxy-vitamin D or 1,25-dihydroxy-vitamin D is sometimes indicated.