Abstract
OBJECTIVE: To monitor the regularity of blood pressure changes in preterm infants with a gestational age of 28 to <37 weeks within 7 days after birth. METHOD: A retrospective analysis was conducted on preterm infants who were hospitalized in the Department of Neonatology of our hospital from January 2022 to January 2025, received non-invasive arterial blood pressure monitoring, and did not receive treatment for hypotension. Basic information of preterm infants (with a gestational age of 28 to <37 weeks) and their mothers, blood pressure data within 7 days after birth, clinical outcomes, and complication status were collected. The blood pressure variation trend of preterm infants (with a gestational age of 28 to <37 weeks) without hypotension treatment was analyzed to provide data support for establishing the blood pressure reference ranges for preterm infants in different gestational age subgroups. RESULTS: A total of 191 preterm infants with a gestational age of 28 to <37 weeks were included. Both systolic blood pressure (SBP) and mean arterial pressure (MAP) demonstrated an upward trend within 7 days after birth (P < 0.001). For SBP: There were significant differences between the 1st postnatal day and the 3rd to 7th postnatal days, as well as between the 2nd postnatal day and the 6th postnatal day. No significant differences in SBP were observed between other time points. For MAP: Significant differences were noted between the 1st postnatal day and the 5th to 6th postnatal days, and between the 2nd postnatal day and the 6th postnatal day. No significant differences in MAP were found between other time points. No obvious variation trend was observed in diastolic blood pressure (DBP) within 1 week after birth. CONCLUSION: Within 7 days after birth, SBP and MAP of preterm infants with a gestational age of 28 to <37 weeks show a spontaneous upward trend with the increase of postnatal age, among which the increase of SBP is more obvious and tends to stabilize about 3 days after birth. The postnatal blood pressure reference ranges vary among preterm infants of different gestational ages, which provides a reference basis for the early postnatal blood pressure assessment and clinical management of preterm infants with different gestational ages.