Capillary blood parameters are gestational age, birthweight, delivery mode and gender dependent in healthy preterm and term infants.

Objectives: The measurement of blood pH and gas analytes (BPGA), soon after birth, constitutes the first-line standard of care procedure in high-risk newborns. However, no data is available in capillary blood on perinatal bias such as gestational age (GA), weight at birth (BW), delivery mode, and gender. The aims of the present study were to investigate whether in a cohort of healthy preterm (PT) and term (T) infants BPGA were GA, BW, delivery mode and gender dependent, thus affecting BPGA reliability as diagnostic test.

Methods: We performed a prospective case-control study in 560 healthy infants (PT: n=115, T: n=445). BPGA was measured within 24-h from birth. Perinatal characteristics, outcomes, and clinical examination were also recorded.

Results: PT infants showed higher (p<0.001) carbon dioxide partial pressure (pCO₂), fraction of fetal hemoglobin (HbF), base excess (BE), bicarbonate (HCO₃), and lower lactate (Lac) levels. When corrected for delivery mode, higher (p<0.001) HbF, BE, HCO₃, and lower Lac levels were found. Similarly, higher (p<0.05, for all) pCO₂, HbF, BE, HCO₃ and lower Lac levels were found between female and male PT and T infants. Repeated multiple logistic regression analysis showed that BPGA was GA, BW, delivery mode and gender dependent.

Conclusions: The present results showing that BPGA can be affected by a series of perinatal outcomes open the way to further investigations providing longitudinal BPGA reference curves in the transitional phase, thus empowering BPGA role as a reliable diagnostic and therapeutic strategies efficacy marker.