Preterm birth is associated with an increased fundamental frequency of spontaneous crying in human infants at term-equivalent age

Biology Letters, Aug 2014

Human infant crying has been researched as a non-invasive tool for assessing neurophysiological states at an early developmental stage. Little is known about the acoustic features of spontaneous cries in preterm infants, although their pain-induced cries are at a higher fundamental frequency (F0) before term-equivalent age. In this study, we investigated the effects of gestational age, body size at recording and intrauterine growth retardation (IUGR) on the F0 of spontaneous cries in healthy preterm and full-term infants at term-equivalent age. We found that shorter gestational age was significantly associated with higher F0, although neither smaller body size at recording nor IUGR was related to increased F0 in preterm infants. These findings suggest that the increased F0 of spontaneous cries is not caused by their smaller body size, but instead might be caused by more complicated neurophysiological states owing to their different intrauterine and extrauterine experiences.

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Preterm birth is associated with an increased fundamental frequency of spontaneous crying in human infants at term-equivalent age

Yuta Shinya Masahiko Kawai Fusako Niwa Masako Myowa-Yamakoshi frequency of spontaneous crying in human infants at Articles on similar topics can be found in the following collections behaviour (758 articles) developmental biology (60 articles) neuroscience (95 articles) Receive free email alerts when new articles cite this article - sign up in the box at the top right-hand corner of the article or click here References Subject collections Email alerting service rsbl.royalsocietypublishing.org Research Cite this article: Shinya Y, Kawai M, Niwa F, Myowa-Yamakoshi M. 2014 Preterm birth is associated with an increased fundamental frequency of spontaneous crying in human infants at term-equivalent age. Biol. Lett. 10: 20140350. http://dx.doi.org/10.1098/rsbl.2014.0350 Author for correspondence: Masako Myowa-Yamakoshi e-mail: Electronic supplementary material is available at http://dx.doi.org/10.1098/rsbl.2014.0350 or via http://rsbl.royalsocietypublishing.org. Animal behaviour Preterm birth is associated with an increased fundamental frequency of spontaneous crying in human infants at term-equivalent age Yuta Shinya1,3, Masahiko Kawai2, Fusako Niwa2 and Masako Myowa-Yamakoshi1 3Japan Society for the Promotion of Science, Tokyo, Japan Human infant crying has been researched as a non-invasive tool for assessing neurophysiological states at an early developmental stage. Little is known about the acoustic features of spontaneous cries in preterm infants, although their pain-induced cries are at a higher fundamental frequency (F0) before term-equivalent age. In this study, we investigated the effects of gestational age, body size at recording and intrauterine growth retardation (IUGR) on the F0 of spontaneous cries in healthy preterm and full-term infants at term-equivalent age. We found that shorter gestational age was significantly associated with higher F0, although neither smaller body size at recording nor IUGR was related to increased F0 in preterm infants. These findings suggest that the increased F0 of spontaneous cries is not caused by their smaller body size, but instead might be caused by more complicated neurophysiological states owing to their different intrauterine and extrauterine experiences. 1. Introduction For several decades, acoustic features of infant crying have been studied as a possible non-invasive tool for assessing neurophysiological states [15]. Previous studies have indicated that an abnormally high frequency (F0) (e.g. mean F0 . 600 Hz) of infant cries is associated with medical conditions, including chromosomal, endocrine, metabolic and neurological disturbances at an early developmental stage [1]. Preterm birth is also a factor in higher F0 cries during early infancy [1 3]. Pain-induced cries in preterm infants have been reported to be higher in F0 before term-equivalent age compared with those of full-term newborns [2,3], although such differences disappeared around term-equivalent age [2,4]. A higher vocal F0 is generally related to smaller body size, especially shorter vocal folds [6]; therefore, it is possible that the higher F0 of preterm infants simply reflects premature body development. Vocal F0 also depends on a complex interaction between laryngeal and respiratory controls [1,6]. Specifically, vagal inputs from the right nucleus ambiguus of the medulla are assumed to have inhibitory effects on laryngeal muscle contraction and tightening of the vocal folds [5]. Therefore, diminished vagal activity might cause laryngeal muscle contraction and tightening of the vocal folds, resulting in a higher F0 [5]. As preterm infants exhibit reduced vagal activity even at term-equivalent age [7], the F0 of their cries might be affected by the altered vagal activity as well as smaller body size. & 2014 The Authors. Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original author and source are credited. minimum F0 (Hz) mean F0 (Hz) maximum F0 (Hz) VP (n 5 22) MLP (n 5 22) FT (n 5 20) However, the effects of body size and other factors related to neurophysiological states (e.g. intrauterine growth retardation (IUGR)) on the F0 of cries in preterm infants have not been investigated [2 4]. In addition, although spontaneous cries (those unaffected by external acute stress) have a higher internal consistency than pain-induced cries in full-term neonates [8], to our knowledge, no studies have assessed the F0 of spontaneous cries in preterm infants. In this study, we performed acoustic analysis of the F0 of spontaneous cries before feeding in both healthy preterm infants at term-equivalent ages and full-term newborns. We investigated the effects of gestational age, body size at recording and IUGR on F0 to assess the relationship between preterm birth and the F0 of spontaneous cries at term-equivalent ages. 2. Material and methods (a) Participants (...truncated)


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Yuta Shinya, Masahiko Kawai, Fusako Niwa, Masako Myowa-Yamakoshi. Preterm birth is associated with an increased fundamental frequency of spontaneous crying in human infants at term-equivalent age, Biology Letters, 2014, 10/8, DOI: 10.1098/rsbl.2014.0350