Fifteen appropriate-for-date premature low-birthweight infants with cystic periventricular leukomalacia (PVL) were studied. The infants were stratified into three birthweight groups: less than 1000 g, 1000 g and greater but less than 1500 g, and 1500 g or greater. Reported and new risk factors for PVL were compared with control patients for all patients and each birthweight group. Hypocarbia was significantly related to cystic PVL, especially in infants with birthweight 1000 g or greater (p < 0.03). Sensitivity to hypocarbia might be decreased in infants with birthweight less than 1000 g due to therapy or prematurity. In the group with birthweight less than 1000 g, the proportion of cystic PVL infants on continuous intra-arterial blood-pressure monitoring tended to be lower than the controls, with an almost significant difference (p = 0.05). The duration of tocolysis was significantly longer in the cystic PVL infants than in the controls when the birthweight was greater than 1500 g (p < 0.04). For some risk factors, a significant difference or a tendency of difference was demonstrated only after stratifying the birthweight. For others, the difference became insignificant after stratification. Assessing risk factors after stratifying by birthweight or degree of prematurity is therefore useful.
Conclusion: The results suggest that hypocarbia should be avoided to prevent cystic PVL, especially in infants with birthweight of 1000 g or greater, continuous intra-arterial blood-pressure monitoring may be important in infants with birthweight less than 1000 g, and fetal status should be monitored carefully when the duration of tocolysis is prolonged, especially in infants with birthweight of 1500 g or more.