Determinants of blood pressure in very low birth weight neonates: Lack of effect of antenatal steroids

Objectives: To define the range of normal blood pressures (BP) for very low birth weight (VLBW; ≤ 1500 g) neonates and to study perinatal variables affecting BP measurements after birth, including the effects of antenatal steroids. Study design: Antenatal steroids were rarely administered at Parkland Memorial Hospital before May 1994, permitting us to establish a cohort of VLBW neonates exposed to antenatal steroids [n = 70, 1166 ± 253 (S.D.) g, and 28.7 ± 2.1 weeks] who were matched with neonates delivered during the prior year (n = 46, 1100 ± 241 g, 28.9 ± 1.8 weeks). Maternal and neonatal charts were abstracted for pertinent data, and neonatal BP measurements (determined directly when an arterial catheter was available or indirectly by the oscillometric method) were extracted every 3 h for the first 12 h and every 6 h until 72 h postnatal. Results: Antenatal steroids did not affect BP immediately after birth or for the subsequent 72 h postnatal. Therefore, data from all neonates ≤ 1500 g were combined and the pattern of BP change over 72 h postnatal assessed. Systolic, diastolic and mean BP increased (P < 0.001) 33%, 44% and 38%, respectively, during the first 72 h. Although neonates weighing ≤ 1000 g and 1001-1500 g demonstrated gradual increases (P < 0.001) in systolic, diastolic and mean BP by 72 h, values were consistently lower (P < 0.01) in neonates ≤ 1000 g. Of interest, only 11 neonates (9.5%) were treated for clinical hypotension. Conclusions: In VLBW neonates antenatal steroids do not modify BP measurements either immediately after birth or the 30-40% rise occurring in the first 72 h postnatal. Further, BP is developmentally regulated and is gestationally and birth weight dependent. These data provide additional insight into assessing the need for treating hypotension. (C) 2000 Elsevier Science Ireland Ltd.