Participants
A sample of 27 LGA mother-neonate pairs were recruited from the SJD Barcelona Children’s Hospital (Catalonia, Spain) between April 2019 and January 2020. Two cases were excluded because the FFR signal could not be identified (i.e., the FFR’s signal-to-noise ration computed in the consonant transition and/or vowel regions <0; see below). Thus, the final sample included 25 LGA neonates and 25 neonates born AGA, all paired by sex and gestational age (GA) at birth (Table 1). AGA neonates were drawn from a larger cohort assessed in a previous study39. In case that a LGA case could be paired with more than one AGA neonate, the AGA pair was selected randomly using Matlab (R2019b, Mathworks) .
AGA and LGA neonates were defined as those with a birth weight between >10th and ≤90thpercentiles and >90th percentile, respectively55. Exclusion criteria were multiple gestations, preterm delivery, preeclampsia, chromosomal or major structural abnormalities or risk factors associated with hearing impairment56. Also, since pre-gestational and gestational diabetes mellitus have been associated with increased risk of maternal and perinatal adverse outcomes57,58, cases affected by these clinical conditions were also excluded. To monitor and detect a possible late gestational diabetes debut, in addition to the O’Sullivan test and the subsequent oral glucose tolerance test (OGTT) implemented for positive O’Sullivan cases, a further OGTT was carried out in those pregnant women with a fetus diagnosed of LGA. This further OGTT was implemented after the LGA diagnosis following the hospital LGA care guide, resulting in a negative result in all our cases. The specific protocol of this study was approved by the institutional Ethics Committee of Clinical Research (CEIC) of the Sant Joan de Déu Foundation (Approval ID: PIC-53-17) and all parents gave the informed consent in compliance with the Declaration of Helsinki.