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
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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)