Effect of dexamethasone on blood pressure--relationship to postnatal age.

The relationship of the change in blood pressure levels of very preterm infants treated with dexamethasone to postnatal age was investigated. Sixteen infants, median gestational age 26 weeks (range 23-33) (early treatment group), and 15 infants, median gestational age 26 weeks (range 24-32) (late treatment group) were recruited. Dexamethasone was administered at a median postnatal age of 17 days (range 3-26) and 50 days (range 29-112), respectively. The systolic blood pressure at the start of treatment and the maximum systolic blood pressure achieved during therapy were both significantly lower (P less than 0.01) in the early rather than the late treatment group. The change in blood pressure, however, that is, from the pre-treatment level to the maximum systolic blood pressure achieved during therapy, was similar in the two groups (median 38 mmHg, range 23-59 early treatment group and median 34 mmHg, range 16-66 late treatment group). We conclude that, even in the first 4 weeks of life, dexamethasone can cause a marked elevation of systolic blood pressure. As a consequence, regardless of the postnatal age at which dexamethasone is administered, blood pressure levels must be measured regularly.