Echocardiographic assessment of brain sparing in small-for-gestational age infants and association with neonatal outcomes

Brain sparing is an adaptive phenomenon (redistribution of blood flow to the brain) observed in fetuses exposed to chronic hypoxia, who are at risk of intrauterine growth restriction. Here, we assessed the blood flow distribution during the early neonatal period (< 7 days of life) using echocardiography, and evaluated the impact of brain-sparing on postnatal course and neurodevelopmental outcomes. This retrospective study included 42 small-for-gestational age (SGA) infants [further classified into asymmetric SGA (a-SGA, n = 21) and symmetric SGA (s-SGA, n = 21) groups according to their birth head circumference percentiles], and 1: 2 matched appropriate-for-gestational age (AGA) infants (n = 84) admitted to the neonatal intensive care unit. Left ventricular (LV) stroke volume, LV cardiac output (LVCO), upper body blood flow (UBBF), and UBBF/LVCO ratio (%) were significantly higher in both a-SGA and s-SGA infants than in AGA infants. Both a-SGA and s-SGA groups consisted predominantly of infants with higher UBBF/LVCO (%). A UBBF/LVCO ≥ 58.2% (3rd interquartile range) was associated with a later need for rehabilitative therapy after discharge. In summary, brain-sparing effect may continue during the early postnatal life in SGA infants, and may be a promising marker to detect future adverse neurodevelopmental outcomes.