Effect of seasonal variation in daylight on bilirubin level in premature infants

Abstract

The effect of daylight on the serum bilirubin level of preterm infants (birthweight < 2500 g) during the first 10 days of life was studied in a district of Finland (Oulu, latitude 65°1') with large seasonal variations in the length of daylight (range 3 to 22 hr). Eighty six preterm infants born consecutively during one calendar year were studied in incubators where they were completely exposed except for nappies. A significantly lower bilirubin value from the 5th day of life onwards was recorded in the group of infants born during the light half of the year, compared with the infants born during the dark half of the year. Only 4 infants developed total bilirubin levels higher than 255 μmol/l in the 'light group', as compared with 10 in the 'dark group'. Two infants in the light group required exchange transfusion, while 4 in the dark group did. It is concluded that natural light conditions are of importance in the design of wards for newborn infants.