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Increased
Carrying Reduces Infant Crying: A Randomized Controlled Trial
Urs A.
Hunziker, MD, and Ronald G. Barr, MDCM, FRCP(C) From the
Department of Pediatrics, The McGill University-Montreal
Children's Hospital Research Institute, Montreal, Quebec,
Canada.
ABSTRACT.
The crying pattern of normal infants in industrialized societies
is characterized by an overall increase until 6 weeks of age
followed by a decline until 4 months of age with a preponderance
of evening crying. We hypothesized that this "normal"
crying could be reduced by supplemental carrying, that is,
increased carrying throughout the day in addition to that which
occurs during feeding and in response to crying. In a randomized
controlled trial, 99 mother-infant pairs were assigned to an
increased carrying or control group. At the time of peak crying
(6 weeks of age), infants who received supplemental carrying
cried and fussed 43% less (1.23 u 2.16 h/d) overall, and 51%
less (0.63 u 1.28 hours) during the evening hours (4 PM to
midnight). Similar but smaller decreases occurred at 4,8, and 12
weeks of age. Decreased crying and fussing were associated with
increased contentment and feeding frequency but no change in
feeding duration or sleep. We conclude that supplemental
carrying modifies "normal" crying by reducing the
duration and altering the typical pattern of crying and fussing
in the first 3 months of life. The relative lack of carrying in
our society may predispose to crying and colic in normal
infants. Pediatrics 1986;77:641-648; crying, carrying, colic,-
mother-infant interaction.
All normal
infants cry. In our society, crying typically occurs in a
pattern characterized by an increase in crying duration until
about 6 weeks of age, followed by a gradual decrease until 4
months of age.1'4 Within the day, crying is increasingly
prevalent during the late afternoon and evening hours.1'2'4'5
Although we have come to regard this crying pattern as
"normal,"!'6 infants with similar crying patterns are
frequently brought to pediatric clinicians as crying problems.
Not uncommonly, they are labeled as having "paroxysmal
fussing" or "3-month colic,"1'2'7"9
variously estimated to affect about 20% of normal
newborns.2'9'10 In recent years, crying has come under
increasing scrutiny, not only because of its theoretical
importance in early mother-infant interaction,11'14 but also
because of its clinical importance as a cause of maternal
distress,12 a cause of discontinuation of breast-feeding,5 and a
stimulus for child abuse.
Despite its salience for both parents and clinicians, remarkably
little is known of the conditions associated with infant
care-taking practices that might contribute to or modulate
crying behavior. This lack of information is more striking in
the light of anecdotal reports from cross-cultural studies of
little or no prolonged fussiness in societies in which infant
care practices differ significantly from our own.17"20
Among the many differences, infant care giving is characterized
by constant close mother-infant proximity and extended
carrying.17' 21 The soothing effects of carrying and rocking
have long been appreciated, and short-term studies examining
elements of these complex behaviors have supported the concept
that they reduce crying, shift arousal to stares of increased
visual and auditory alertness, and produce soothing effects
which persist postintervention.22"33 In our society,
picking up and holding are also the most frequently used and
effective soothing behaviors"'34 but are typically elicited
in response to crying. In addition, mothers have less direct
contact and a greater relative distance from their
infants.17'21'22 Although constant carrying is unlikely to
become the typical infant care-taking practice in our society,
we hypothesized that the "normal" crying pattern might
be changed by supplemental carrying, that is, increased carrying
throughout the day in addition to that which occurs during
feeding. If so, such carrying might have anticipator.- soothing
effectiveness in normal infants and therapeutic or preventative
value in relation to infant "colic."
METHODS
Overall Design
The study was a randomized controlled trial to assess the
effectiveness of supplemental parental carrying in reducing
crying/fussing behavior of normal infants between 3 and 12 weeks
of age. Normal mother-infant pairs were recruited at birth and
entered the trial when the baby was 3 weeks of age. After
obtaining baseline data for 1 week, subjects were randomized to
a supplemental carrying or control group. In the supplemented
group, parents were asked to carry their baby in their arms or
in a carrier for at least three hours a day. In the control
group, parents were asked to situate their baby facing a mobile
and an "abstract" of a face when the baby was placed
in the crib. Infant behaviors, including crying and fussing, and
parental activities directed toward the infant were monitored by
diaries completed by the parent(s) at week 3 (baseline) and when
the baby was 4, 6, 8, and 12 weeks of age. The study was
approved by the Montreal Children's Hospital Committee on
Medical and Dental Evaluation and all participating mothers gave
written informed consent.
Subjects
Between June and November 1983, 234 eligible mother-infant pairs
were approached on maternity wards of two general hospitals in
central Montreal. AU infants eligible for the study were
breast-fed, first-born at term with a birth weight of at least
2,500 g and had uncomplicated pre-, peri-, and postnatal
histories. The nature of the trial was explained and they were
told that, if they participated, the form of additional
stimulation (carrying or visual) they would be asked to provide
would be determined randomly (by chance). Of those who were
eligible, 50% (n = 117) agreed to participate at 3 weeks. By
randomization, 59 babies were assigned to the supplemented group
(ten subsequently dropped out); 58 were assigned to the control
group (eight left the study). Reasons given for discontinuation
were maternal inconvenience (n = 11), including the work of
completing diaries regularly (missing 2 weeks or more), being
too busy, and maternal illness; infant illness (n = 1); and
miscellaneous (n = 6), including diaries lost in the mail and
change of residence. Subjects who discontinued the study
differed from those who remained: those who left were of lower
socioeconomic status (61 o 68 by Green Index,35 unpaired t =
3.02, P < .01) and younger (26 u 29 years, unpaired t = 2.68,
P < .01) but they were not different on neonatal indices
(duration of gestation, birth weight, Apgar score at one and
five minutes), infant characteristics (sex, race) and remaining
parental characteristics (religion, language, marital status,
age of father). In the remaining 49 supplemented and 50 control
subjects, there were no differences on any of the above infant
or parental variables (Table). Size of this study population was
determined a priori on the assumption that a reduction of 25% in
daily crying/fussing behavior would be a meaningful behavioral
change. We used previously available data36 to determine that a
sample size of 45 subjects per group would be sufficient for a
decrease of this magnitude to occur by chance in only 5% of
samples, whereas a true decrease would fail to be seen in 20%.
For some subjects, 1 week of diary data was missing, but missing
data never exceeded 10% of the total for either group for any
week.
Parental Diaries
Parents recorded their baby's behaviors and their own activities
in pretested continuous 24-hour diaries. One complete day was
represented on each sheet by four horizontal "time"
bars, each subdivided into five-minute units. The upper half of
each bar was used for recording infant behaviors of sleeping,
awake and content, crying, fussing, and feeding. The lower half
was used for recording parental activities of carrying with body
contact, moving with the baby but without body contact (ie, in a
car or a pram) and care-taking activities (ie, changing,
bathing, dressing the baby). The duration of each behavior was
indicated by filling in these bars with a symbol assigned to
each behavior. The diaries of the supplemental and control
groups differed only in the name given to the symbol
representing the intervention. For the baseline recording (week
3), this category was omitted for both groups.
Validation for short-term use of the parental diary was
undertaken prior to the study by a direct comparison of parental
diary recordings of crying and fussing with electronically
recorded crying (negative vocalizations) during 24 hours in ten
mother-infant pairs. Moderately strong product-moment
correlations were obtained between duration of diary-recorded
crying and negative vocalization (/• = .65, P < .05) and
between frequency of crying/fussing episodes and clusters of
negative vocalizations (r = .71, P < .05).37 If one poorly
completed diary recording was eliminated, the strength of
association of the recording methods for these measures improved
further to .89 and .85, respectively (P < .01).
The dependent measures of infant behavior derived from the
diaries were duration (hours per day) and frequency (episodes
per day) of crying/fussing (crying and fussing combined),
sleeping, awake and content, and feeding. The same measures were
derived for parental activities of carrying with body contact,
moving baby without body contact, and care taking. These
measures were also derived for three periods of the day: night
(midnight to 8 am), day (8 AM to 4 PM) and evening (4 PM to
midnight). To monitor potential recording bias introduced by the
different interventions, parents also recorded the frequency of
five infant behaviors presumed not to be affected by parental
carrying, specifically hiccups, bowel movements, regurgitation,
vomiting, and tremors.
Procedure
At the
time of recruitment, eligible mothers were provided with the
diary and verbal and written instructions regarding its use. At
week 3, parents were contacted by telephone to determine whether
they wished to be study participants. Participating parents were
then asked to complete the diary for 1 week. At the end of week
3, parents were assigned by random number to the supplemented or
control group, and they were then visited at their homes.
Diaries were reviewed and new diaries were provided for the
remainder of the study. In the supplemented group, parents were
asked to carry their baby for a minimum of three hours per day
and it was emphasized that carrying should occur throughout the
day, not only in response to crying, in addition to carrying
during feeding, and independent of whether the baby was awake or
asleep. In the control group, parents were asked to expose their
infant to the visual stimuli when they were placed in the crib,
but they were not asked to increase time in the crib. The
investigators provided infant carriers to the supplemented group
and mobiles and face pictures to the control group. To minimize
recording bias, the purpose of the study was described as being
the study of the effect of additional amounts of common
stimulation on the development of behavioral rhythms (sleep,
feeding, regurgitation, etc) in normal infants. Neither the
specific hypothesis nor the crying target variables (crying and
fussing) were identified to the parents. During weeks 4 to 12,
the parents were contacted by telephone at the beginning of each
week scheduled for diary recording. Completed diaries were
returned by mail after each week of recording. At the end of
week 12, parents were asked about the type of current feeding
(breast, formula, mixed) and whether the pacifier had been used
frequently or rarely.
Data Analysis
A research assistant blind to the study hypothesis transferred
the parental recordings of each diary sheet to an identical
diary analogue displayed on the screen of a computer terminal.
Compilation of frequencies and duration of behaviors, data
reduction, and analyses were accomplished by programs developed
for this study. Between-group differences were analyzed by
planned comparisons using Student's one-way t test of the means
of independent samples.
Fig.1
Daily duration of infant crying/fussing in re-sponse to change
in parental carrying. Top: Means and SD of crying/fussing
behavior in hours per day averaged over each week of parental
recording for supplemented (0, - - -) and control (o, --)
infants, respectively. Intervention (see text) for both groups
started at begin-ning of week 4 after 1 week of baseline
recording (week 3). Bottom: Means and SD of carrying in hours
per day averaged over each week of parental recording for
sup-plemented and control groups. Carrying during interven-tion
in supplemented group is represented by method of holding in
parent's arms or in infant carrier.
RESULTS
As expected, the mean daily duration of carrying of supplemented
and control infants was similar during week 3 (3.4 y 2.7 h/d, P
> .05; Fig 1, bottom). At each of weeks 4 to 12, parents in
the supplemented group did significantly more carrying, the
difference ranging from 2.1 h/d at week 4 to 1.5 h/ .-d at week
12 (average 1.8 h/d; all P < .001). As a result, the
supplemented infants were carried an average of 4.4 h/d during
the intervention period, of which 3.5 hours was in the parent's
arms and 0.9 hours was in the carrier. The control infants were
carried an average of 2.7 h/d throughout this intervention
period.
Increased carrying changed the typical pattern of combined
crying and fussing duration (crying/fussing) of infants after
the intervention began (Fig 1, top). In the control group, the
"normal" crying/ fussing curve started at 1.7 h/d
(week 3), peaked at 2.2 h/d (week 6), and decreased to 1.3 h/d
at week 12. In supplemented babies, however, the peak at week 6
was eliminated. Duration of crying/fussing was longest at week 3
(1.8 h/d) and was followed by a gradual decrease to 1.0 h/d at
week 12. The differences were-significant at weeks 6, 8 (P <
.001), and 12 (P < .05) and represented reductions of
crying/fussing duration of 43%, 41%, and 23% respectively: If
crying and fussing were considered separately, the patterns of
differences between the groups were similar. Significant
differences occurred at 6, 8, and 12 weeks for crying and 6 and
8 weeks for fussing (all P < .05).
The changes in crying/fussing duration within the day are
displayed in Fig 2.
Fig.2
Distribution of infant crying/fussing behavior within day. Mean
crying/fussing behavior in minutes per hour at each hour of day
for supplemented and control infants during baseline (week 3)
and during weeks 4, 6, 8, and 12 of the intervention period.
The typical clustering of crying during the evening remained the
same for both groups at all ages. However, although the
supplemented group tended to have less crying/ fussing behavior
throughout the day, these differences were particularly striking
during the evening, representing a reduction of 54% and 47% at
weeks 6 and 8, respectively. Significant reductions within the
day occurred at week 6 during the day (0.4 u 0.6 hours, P <
.005), evening (0.6 u 1.3 hours; P < .005), and night (0.2 u
0.3 hours; P < .01). At week 8, significant reductions
occurred during the day (0.4 v 0.6 hours; P < .001) and
evening (0.5 v 1.0 hours; P < .001). There were no
significant differences within the day during weeks 4 and 12.
To determine which other behaviors may have been affected,
similar analyses were performed post hoc for feeding, sleeping,
and awake and content duration. There were no differences in
feeding or sleeping duration at any age; however, awake and
content behavior was significantly increased in the supplemented
babies at weeks 4 (4.1 u 3.8 h/d), 6 (5.6 u 4.6 h/d), and 8 (6.0
u 5.0 h/d; all P < .01). It appeared, therefore, that reduced
crying/fussing was replaced by increased awake and content
behavior during this time.
During the intervention period, the feeding frequency calculated
in mean episodes per day was higher in the supplemented compared
with the control group, averaging 8.8 u 7.2 episodes per day (P
< .025 at all weeks). This was in contrast to the frequency
measures calculated for all other infant behaviors
(crying/fussing, sleeping, feeding, awake and content) which
were similar in both groups during all weeks. In addition, there
were no between-group differences in frequency of hiccups, bowel
movements, regurgitation, vomiting, or tremors. With respect to
the retrospective question concerning pacifier use, frequent use
was reported by 70% of the control parents o 47% of the parents
of supplemented babies (x2 = 5.15, P < .05). Forty-five
percent of supplemented and 40% of control parents reported
having introduced partial or total formula feeding by the end of
the study period (P > .05).
DISCUSSION
The
results of the present study demonstrate that increased parental
carrying was associated with a substantial reduction in crying
and fussing behavior in these first-born, breast-feeding infants
during the first 3 months of life. This behavioral change was
particularly apparent in relation to two of the characteristics
of crying of normal infants noted in our control group and in
previous studies namely, elimination of the peak at 6 weeks of
age and diminution of the crying and fussing that clusters
during the evening. This reduction appeared to be replaced by
increased awake contentment rather than changes in sleeping or
feeding duration. The difference was most marked by 6 weeks of
age when an increase in carrying time of two hours was
associated with an overall reduction of one hour (43%) in crying
and fussing behavior. Whether these findings can be generalized
to bottle feeders, later parity infants, infants with younger
mothers and lower socioeconomic status, or mother-infant pairs
who choose not to participate in such studies cannot be
determined from this study.
There are a number of reasons why the increased carrying might
have been effective, related both to its content and timing. In
all societies, there are a variety of everyday techniques that
are used to calm a crying baby such as picking up, rocking,
patting, cuddling, and swaddling. Such soothing behaviors share
the characteristics of postural change, repetitiveness,
constancy and/or rhythmicity, close proximity between mother and
infant, and the involvement of many sensory modalities. In
short-term experiments with newborns who are already crying or
in whom cries have been elicited, many of the elements of these
complex behaviors have been shown to soothe
infants.22-24'26-29-31-33 Similarly, in naturalistic
observations in the home, picking up and holding was the most
frequent and most effective intervention in response to crying,
with other effective interventions being swaddling, presence of
a human voice, contact, and visual stimulation.11'34 These
interventions all imply relatively more mother-infant proximity,
which correlates inversely with incidence of crying behavior.11
Wolff34 noted that psychologically significant interventions
such as the human voice (compared to nonhuman sounds) and human
figures (compared to visual distraction in general) become
increasingly important as effective soothing interventions after
the second week of life. The supplemental carrying received by
the experimental group would have effectively increased
mother-infant proximity and the exposure of these infants to
both physiologic and psychologic forms of these soothing
behaviors throughout the intervention period.
It is possible, however, that the timing rather than the content
of the supplemental carrying better explains its effectiveness.
In the supplemented group, the mothers were encouraged to carry
their infants throughout the day regardless of the state of the
infant and not just in response to crying or fussing. Previous
investigations have demonstrated the importance of environmental
factors in modulating early infant behavior and have focused on
the sensitivity of the care giver to infant signals and the
immediacy of the care giver response.11'38 The increase in
carrying could have systematically predisposed these mothers to
detecting their infant's demands and to shortening the response
time to infant distress, thereby facilitating a more synchronous
mother-infant interaction.38 Alternatively, the increased
carrying may have acted to reduce infant demands by maintaining
the infant's state of quiet alertness.22'23'28'39'40 Gentle
rocking of quiet newborn infants in a bassinet or a caretaker's
arms has been shown to be effective in delaying or reducing
later crying in short-term observations.41'42 Consequently, the
supplemental carrying could have the effect of increasing
parental responsivity and/or lowering the infants' arousal
levels throughout the day. In this sense, the supplemental
carrying "anticipates" and possibly prevents the
behavioral decompensation represented by crying and fussing that
would otherwise occur later in the day. The anticipatory nature
of the carrying may be particularly important in relation to the
clinical syndrome of infant colic, because these infants are
often described as being unresponsive to carrying initiated
after the crying has begun.7'8
SPECULATION
AND RELEVANCE
The
rather impressive change implies that this pattern of crying in
the first 3 months of life is only normal in the sense of being
typical for infant care-giving practices of our society.
However, these findings do not demonstrate that absence of
carrying is either a necessary or a sufficient cause of infant
crying. It is probable that this particular pattern reflects
underlying biologic changes, the behavioral manifestations of
which are subject to modulation by different care-taking
practices. For example, the changes in crying may represent
changes in development and maturation of the nervous system
facilitated by favorable interaction with the care-taking
environment.1'3'14 Additionally, crying and fussing could be
initiated by the stimulus of intraintestinal gas production
secondary to the incomplete carbohydrate absorption which
persists into the third month of life in response to typical
feeding patterns.36'43 Whatever the particular constraints
imposed by these biologic factors, the behavioral manifestations
nevertheless remain subject in part to environmental influence.
Consequently, normal crying most likely represents a
culture-specific pattern reflecting the interaction between
biologic factors and infant care-giving practices typical of our
society.
We speculate that the potential for changing infant-carrying
patterns may have important clinical consequences. Early infant
crying is an adaptive behavior that acts to promote
mother-infant proximity and to provide opportunities for social
interaction.11'14 These opportunities usually result in
elicitation of appropriate emotional-motivational reactions,
care and feeding behavior, and parent-child attachment.3'11'12
The increased carrying reduces crying behavior but promotes
proximity so that crying is less necessary. In addition, the
associated increased awake contentment would likely be
associated with a state of quite alertness and visual
exploration necessary for positive social contact.25'30 If an
infant's crying behavior is considered excessive, however, it
may promote negative interactions12 and increase the frequency
of clinical complaints. Excessive crying has been associated
with the erosion of positive emotions and coping skills in
mothers,44'45 parental responses that are less plentiful and of
poorer quality,46 and occasionally episodes of child abuse.ls'16
In clinical practice, complaints of crying typically present as
feeding problems or as colic. Because parents commonly perceive
crying as hunger, elimination of the crying peak may remove one
impetus to engage in formula changes, discontinue
breast-feeding, or begin early solid food intake.5'47 Indeed,
the associated increased feeding frequency noted with the
carried infants might also facilitate early weight gain, prolong
breast-feeding, and diminish the insufficient milk syndrome in
breast-feeding infants.48'49 Finally, increased carrying,
particularly anticipatory carrying throughout the day, may
represent a relatively simple nonpharmacologic therapeutic
intervention for colic, because there is a close similarity
between the patterns of crying seen in normal babies and infants
with colic, as well as lack of evidence of pathology in colicky
infants.2'7'9 Alternatively, increased carrying may have
significance as part of pediatric anticipatory guidance.
Overall, supplemental carrying may be a more effective approach
to feeding and crying problems than the more traditional
supplemental bottle.
ACKNOWLEDGMENTS
This study was supported, in part, by grants from the McGill
University-Montreal Children's Hospital Research Institute and
the W. T. Grant Foundation.
Dr Hunziker is a recipient of an investigator award from the
"Kredit zur Förderung des akademischen Nachwachses der
Erziehungsdirektion des Kantons Zurich". Dr Barr is a W. T.
Grant Faculty Scholar.
The authors thank Heinz Spiess of the Departement d'information
et de recherche operationnelle de 1'Université de Montréal for
design of computer software programs and data analysis, James
Hanley, PhD, for statistical advice, Christa Hunziker and Donna
Steinberg for subject recruitment and follow-up, Anne O'Donnell
for technical help, and Maria Szasz and Madeleine Ranger for
secretarial assistance. We thank Drs Philip Zelazo, Barry
Zuckerman, Terence Nolan, and Howard Foye for helpful critical
reviews of the manuscript.
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ON REMODELING SOCIETY
... even if we were determined to, we could never, despite our
dreams of [a perfect society], sweep everything away and begin
again. Mankind is like the crew of a ship at sea who can choose
to remodel any part of the ship they live in, and can remodel it
entirely section by section, but cannot remodel it all at once.
Submitted by Student
From Magee B: Philosophy and the Real World. An Introduction to
Karl Popper. La Salle, IL, Open Court, 1985.
Copyright 1986 by the American Academy of Pediatrics - Published
in PEDIATRICS Vol.77, pages 641-648, No.5 May 1986 Pubblicato su
www.portareipiccoli.it con il gentile permesso dell'autore Dott.
Urs A.Hunziker, agosto 2002
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