Antenatal dexamethasone and renal vascular resistance in preterm infants.

Objective: To compare vascular resistance, renal volume and insulin levels in preterm infants with and without antenatal steroids.

Methods: We studied 61 preterm infants (37 with (group A) and 24 without antecedent of antenatal steroids (group B)). We measured insulin levels at birth in cord blood samples. Ultrasound measurements to evaluate renal arteries resistance index and renal volume were performed during the first 72 h of birth.

Results: Preterm infants from group A tended to have lower weight and gestational age than those from group B. Resistance index in renal arteries was lower in preterm infants with steroid therapy compared with group B (right renal artery 0.73 vs. 0.80; P=0.001, and left renal artery 0.75 vs. 0.79; P=0.01, respectively). Renal volume and insulin levels were not different between the groups. In the multiple regression analysis for factors associated with resistance index of renal arteries, only antenatal steroids use was included in the model (R2=0.13; P=0.003 and R2=0.10; P=0.01 for left and right renal arteries, respectively).

Conclusion: Antenatal dexamethasone in preterm infants during the first 72 h of birth seems to decrease resistance index in renal arteries without affecting renal volume and insulin levels.