Oscillatory Blood Pressure Values in Newborn Infants: Observational Data Over Gestational Ages.

Introduction: Normative blood pressure (BP) values on preterm infants exist but are based on small cohorts of infants. Utilizing electronic medical records (EMR), we can explore earlier gestational ages (GA) and follow their progression to 40 weeks corrected gestational age (CGA).

Methods: A retrospective cohort study of infants within the SSM Health System from July 1, 2013 through June 30, 2023. Infants born at >22 0/7 weeks but <41 weeks GA were included if any BP measurements existed (n = 29,323 infants, 1.4 million BPs). Data were extracted electronically from EMR using Microsoft SQL. Systolic BP (SBP), mean arterial pressures (MAP), and diastolic BP (DBP) were determined for each week of life from birth and percentile ranges (1st to 99th) for infants alive at CGA, and BP patterns for GA determined.

Results: Percentiles for SBP, DBP, and MAP are provided. There is a rapid increase in BP at all gestations during the first 2 weeks, thus BP values are higher at any CGA in infants born at an earlier GA than infants born at that GA. For MAP values between the 5th and 10th percentile, the GA is appropriate for first week and then use CGA + 5 mm Hg. After the first week, 2.8 X CGA is between 90 and 95 percentile for SBP.

Conclusions: The BP is dependent on the GA at birth and the CGA when it is measured. SBP, MAP, and DBP all increase rapidly in the 2 weeks of life prior to a gradual increase over time.