Abstract 1423 Neonatal Epidemiology and Follow-up Poster Symposium, Monday, 5/3

Background: Antenatal corticosteroid (ACS) therapy substantially improves the survival rate of preterm infants, with few known side effects. Higher blood pressure in adulthood has been described in several animal species after exposure to ACS, but there are no similar reports in humans. Objective: To determine the relationship between exposure to ACS and blood pressure at 14 years of age. Methods: This was a cohort study of 210 survivors with birthweights <1501 g born from January 1, 1977, to March 31, 1982, in the Royal Women's Hospital, Melbourne. Blood pressure was measured in 177 (84.3%) of the 210 survivors at 14 years of age with a standard mercury sphygmomanometer by clinicians with no knowledge of the perinatal history of the children. ACS (betamethasone) had been given to the mothers of some children to accelerate fetal lung maturation. Some mothers had participated in a controlled clinical trial of ACS, but in some mothers ACS were given outside of the trial at the discretion of the attending clinician. Results: For those children exposed to ACS, the mean gestational age that ACS had been given antenatally was 28.9 (SD 2.2) weeks. Children exposed to ACS had significantly higher systolic and diastolic blood pressures than those not exposed to ACS (Table) (mean difference between groups, mm Hg, [95% confidence interval]; systolic 4.1 [0.1, 8.0]; diastolic 2.8 [0.1, 5.4]). However, the proportions with clinically important elevations in blood pressure were not significantly different between the groups (Table). Only one child with high blood pressure at 14 years of age had a known cause. This child had a blood pressure of 150/100 mm Hg and was abusing anabolic steroids at 14 years of age, but had not been exposed to ACS. If this child's data were excluded, the differences in blood pressure between the two groups widened by approximately 0.4 mm Hg, and remained statistically significant. Conclusion: ACS might cause hypertension in survivors well beyond birth, which would be a small price for their known survival and other advantages. The Barker hypothesis (that events in the uterus may program health events in adulthood) may be relevant to preterm, as well as term, infants.

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