Newborn blood pressure dynamics during immediate postnatal transition - a retrospective analysis

The transition from intrauterine to extrauterine life presents challenges for neonates, who are at increased risk of cardio-respiratory instability. Although electrocardiogram monitoring is recommended for neonatal resuscitation after birth, its ability to assess cardiovascular function is limited. Measuring arterial blood pressure (ABP) is feasible in neonates during the immediate transition period, though its interpretation is complex. This study analyses ABP values during the immediate transition in preterm neonates.

Data from neonates born at the Medical University of Graz between 2009 and 2023 were analysed. All preterm neonates who survived without intraventricular haemorrhage grade II or higher, and who had ABP measured non-invasively at 15 min after birth, were eligible for inclusion. Statistical analyses were employed to evaluate ABP values for each gestational week, ranging from 23 to 36 weeks of gestation.

Out of 305 eligible neonates, 267 preterm neonates met the inclusion criteria. The median (IQR) systolic ABP ranged from 46 (43-51) to 64 (56-68) mmHg showing a gradual increase with advancing gestational age. The mean ABP ranged from 30 (27-36) to 45 (37-47) mmHg, also exhibiting a gradual increase with higher gestational age. Similarly, the diastolic ABP ranged from 22 (19-29) to 34 (29-41) mmHg, again showing a gradual increase with advancing gestational age.

The findings indicate that ABP values during the immediate transition may be higher than those described after immediate transition in large cohort studies. Moreover, the gradual increase in ABP in preterm neonates with advancing gestational age underscores the necessity for tailored approaches to neonatal cardiovascular management during immediate transition.