We tested healthy preterm (born near 28 ± 2 weeks of gestational age) and full-term infants at various different ages. We compared the two populations on the development of a language acquisition landmark, namely, the ability to distinguish the native language from a rhythmically similar one. This ability is attained 4 months after birth in healthy full-term infants. We measured the induced gamma-band power associated with passive listening to (i) the infants' native language (Spanish), (ii) a rhythmically close language (Italian), and (iii) a rhythmically distant language (Japanese) as a marker of gains in language discrimination. Preterm and full-term infants were matched for neural maturation and duration of exposure to broadcast speech. We found that both full-term and preterm infants only display a response to native speech near 6 months after their term age. Neural maturation seems to constrain advances in speech discrimination at early stages of language acquisition.gamma-band oscillations | preterm infant | speech | rhythm | development H ow much do healthy immature brains gain from exposure to broadcast speech? Unfortunately, very few studies have investigated the interaction between experience and brain maturation in healthy premature infants during the early stages of cognitive development (1). Highly premature infants whose nervous system is immature are confronted with a wide range of external stimulation with unknown consequences on cognitive development. Here, we explore the neural correlate of a landmark of language acquisition, namely, the discrimination of the maternal language from rhythmically similar languages (2).A fair number of behavioral studies have demonstrated that fetuses and neonates distinguish utterances of languages belonging to different rhythmic classes. Indeed, in a recent study, speech perception was examined in 104 low-risk fetuses at 33-41 weeks of gestational age using a familiarization/novelty paradigm (3). One of the experiments shows that fetuses of English-speaking mothers discriminate English from Mandarin, two languages that are very different in rhythm. Moreover, other studies with 2-to 4-day-old neonates and a larger set of language pairs show different responses depending on whether the utterances belong to the same or two different rhythmic classes (2, 4, 5). In other words, once neonates become habituated to utterances of a given language, they show an increase in their nonnutritive sucking rate only when they are exposed to utterances of languages that belong to a different rhythmic class. However, at this age, neonates do not distinguish a switch that occurs between two languages that belong to the same rhythmic class. Other studies have established that it is only after 4 months that full-term infants are able to distinguish utterances in their native language from those of a language that belongs to the same rhythmic class (6, 7). How does this ability develop in healthy highly premature infants? Would preterm infants exposed to their native language for nea...

In early postnatal life, SGA infants display an increased insulin sensitivity with respect to glucose disposal but not with respect to suppression of lipolysis, ketogenesis, and hepatic production of IGFBP-1. It will be important to determine how these differential sensitivities to insulin vary with increasing age.

In prepubertal children, low birth weight is related to reduced insulin sensitivity, particularly if a history of rapid postnatal weight gain is present. We sought to determine whether these associations were also evident in premature, very-low-birth-weight (VLBW) children. We studied 60 VLBW prepubertal children aged 5-7 yr (mean age 5.7 +/- 0.7 yr). Birth weights ranged from 690 to 1500 g (mean 1195 +/- 31 g), with gestational ages between 25 and 34 wk (median 29 wk). A short iv glucose tolerance test was carried out to assess fasting insulin sensitivity and glucose-stimulated insulin secretion. The effects of current body mass index, birth weight (SD scores), postnatal growth rates, and indicators of postnatal morbidity were evaluated by analysis of covariance. Twenty children were born small for gestational age, and 40 were appropriate for gestational age. Ninety-eight percent of them had attained a height within target range. Children who were small for gestational age had lower insulin sensitivity than children who were appropriate for gestational age (homeostasis model assessment insulin resistance index 1.24 +/- 0.17 vs. 0.94 +/- 0.08, P < 0.05). Moreover, birth weight SD scores correlated significantly with homeostasis model assessment insulin resistance index (r = -0.326, P = 0.01). This effect persisted after adjustment for current body mass index, gestational age, and perinatal morbidity. In addition, fasting and postload insulin secretion during the short iv glucose tolerance test correlated significantly with early postnatal growth rates, independently of birth weight SD scores. Our findings in a cohort of VLBW prepubertal children indicate that growth in utero as well as postnatal growth rates are independent determinants of subsequent insulin sensitivity and secretion.

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Background: Rapid early ponderal growth is associated with adverse metabolic risks in young adults born at term. Aim: To determine whether there are differences in body composition, resting energy expenditure (REE) and metabolic variables between preterm children born with very low birth weight (VLBW) either appropriate (AGA) or small (SGA) for gestational age and whether these differences are related to an early period of weight gain. Methods: 67 VLBW preterm (40 AGA, 27 SGA). Body composition by DEXA, REE by indirect calorimetry and blood sampling at age 6.7 ± 0.5 years. Results: VLBW SGA children were lighter, shorter, had a lower waist and hip circumference, HDL cholesterol and lipid oxidation rates than their AGA counterparts (adjusted for age, sex and BMI). Birth weight correlated negatively with total body and trunk fat mass. In a multivariate linear regression analysis, we found a positive association between weight gain in the first 3 months of life and total and trunk fat at age 6 years and a reciprocal association with REE at age 6 years. In contrast, the weight gain rate at 6-9 months of life was associated with higher REE and lipid oxidation rates at 6 years. A higher weight gain rate at 9-12 months was associated with a higher lean mass at 6 years. Conclusion: An early fast-pace weight gain in VLBW infants may have detrimental consequences for metabolic health later on.