This article was downloaded by: [University of Cambridge]On: 16 October 2014, At: 06:21Publisher: RoutledgeInforma Ltd Registered in England and Wales Registered Number: 1072954Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK

Journal of Reproductive and InfantPsychologyPublication details, including instructions for authors andsubscription information:http://www.tandfonline.com/loi/cjri20

Breastfeeding and mother-infantinteractionsAmy L. Kuzela a , Cynthia A. Stifter b & John Worobey ca Temple University , USAb Pennsylvuniu State University , USAc Rutgers University , USAPublished online: 11 Dec 2007.

To cite this article: Amy L. Kuzela , Cynthia A. Stifter & John Worobey (1990) Breastfeedingand mother-infant interactions, Journal of Reproductive and Infant Psychology, 8:3, 185-194,DOI: 10.1080/02646839008403623

To link to this article: http://dx.doi.org/10.1080/02646839008403623

PLEASE SCROLL DOWN FOR ARTICLE

Taylor & Francis makes every effort to ensure the accuracy of all the information(the “Content”) contained in the publications on our platform. However, Taylor& Francis, our agents, and our licensors make no representations or warrantieswhatsoever as to the accuracy, completeness, or suitability for any purpose of theContent. Any opinions and views expressed in this publication are the opinions andviews of the authors, and are not the views of or endorsed by Taylor & Francis. Theaccuracy of the Content should not be relied upon and should be independentlyverified with primary sources of information. Taylor and Francis shall not be liablefor any losses, actions, claims, proceedings, demands, costs, expenses, damages,and other liabilities whatsoever or howsoever caused arising directly or indirectly inconnection with, in relation to or arising out of the use of the Content.

This article may be used for research, teaching, and private study purposes. Anysubstantial or systematic reproduction, redistribution, reselling, loan, sub-licensing,systematic supply, or distribution in any form to anyone is expressly forbidden.Terms & Conditions of access and use can be found at http://www.tandfonline.com/page/terms-and-conditions

Journal of Reproductive and Infant Psychology, Vol. 8,185-194 (1990)

Breastfeeding and Mother-Infant Interactions

AMY L. KUZELA Temple University, USA

CYNTHIA A. STIFTER Pennsylvuniu Stute University, USA

JOHN WOROBEY Rutgers University, USA

ABSTRACT

This study investigated the proposition that breastfeeding facilitates mother-infant interaction in a context beyond feeding. The free-play behaviors of 11 mother-infant pairs in which infants were currently breastfed were compared to 16 bottlefeeding dyads. Coded maternal behaviors included positive instances of play, touch, vocalizations and affect directed towards the infants, and positive vocalizations, reaching and affect by the infants to their mothers. Analyses revealed that currently breastfed mother-infant pairs displayed more maternal touch and less infant vocalizing, but more fussiness. However, breastfed males and bottlefed females exhib- ited the most optimal behaviors, suggesting a sex by feeding interaction effect. The results are discussed with respect to the developing mother-infant relationship.

INTRODUCTION

The nutritional and immunological benefits of breastfeeding are well documented, with nearly complete agreement as to its superiority for most infants (Guthrie, 1989). Close to two-thirds of new mothers in both England and the United States elect to breastfeed, although less than a quarter continue to do so by 6 months postpartum (Martin and Monk, 1982; Martinez and Krieger, 1985). Despite some controversy surrounding the emotional benefits of breastfeeding (Holt and Wolkind, 1983; Stein et al., 1987), there is certain evidence that psychological factors distinguish the breast- from bottlefeeding mother (Newton, 1971; Shand, 1981). For example, more positive attitudes toward their infants (Richards and Bernal, 1971) and more baby/family- centered attitudes (Wiesenfeld et al., 1985) have been shown in breastfeeding moth- ers. This paper explores the hypothesis that the advantages of breastfeeding may

Correspondence should be directed toward Amy Kuzela, Infant Behavior Laboratory, Department of Psychology, Weiss Hall, Temple University, Philadelphia, PA 19122, USA

0264-6838/90/030185-10$05.00 Received 22 August 1989 A ~ , ~ ~ ~ ~ ~ A 33 nnnl, loan

Dow

nloa

ded

by [

Uni

vers

ity o

f C

ambr

idge

] at

06:

21 1

6 O

ctob

er 2

014

186 A. L. Kuzela et al.

extend to maternal and infant behaviors that comprise an adaptive mother-infant relationship.

It has long been shown that the mother’s attitude will, in large measure, determine whether or not she nurses, and subsequently, her degree of success (Newton, 1955; Switzky et al., 1979). Building a relationship between mother and infant is a develop- mental process (Worobey, 1989), therefore, it can be assumed that the mother’s attitudes and feelings toward breastfeeding may not only affect her success, but also the interaction during feeding episodes. If breastfeeding does promote positive interactions between mother and infant, these may further impact on maternal attitudes and feelings toward nursing. Indeed, breastfeeding mothers generally find the experience to be enjoyable (Jones, 1986; Woollett, 1987), with the intimacy and contact of a one-to-one interaction between mother and infant possibly facilitating these attitudes.

The extra contact and affectionate behaviors experienced while breastfeeding would seem to heighten the relationship between mother and infant (Blumen, 1980). For example, in a study of Wiesenfeld et al. (1985), nursing mothers were found to be more responsive to their infants during feeding periods and reported feeling an ‘emotional union’ with them. The most common reasons given by nursing mothers for their choice of feeding method were emotional benefits for the infant such as intimacy, security, and bonding. And, in a subjective measure of emotional response, these mothers reported a greater desire to pick up their infants.

Twenty years ago, Bernal and Richards (1970) found that breastfeeding mother touched, smiled at, and vocalized to their newborns more during nursing than did bottlefeeding mothers when feeding their week-old neonates. Bernal (1972) also found that breastfeeding mothers responded more quickly to their infant’s cries. Quite recently, Walton and Vallelunga (1989) reported that breastfeeding mothers of 6-to-13-week-old infants were more responsive than bottlefeeders during a feeding episode.

Interestingly enough, breastfeeding has also been linked to infant irritability and activity level. Bell (1966), and recently DiPietro et al. (1987), reported breastfed newborns to be more highly aroused than bottlefed neonates. Similarly, Bernal(l972) found that breastfed newborns cried more often than bottlefed newborns, while Worobey (1990) has shown that breastfeeding mothers rate their 3-month-old infants as more motorically active and prone to distress. As breastfeeding has been associated with increased maternal responsitivity (Dunn and Richards, 1977), a number of researchers have suggested that infant irritability may provide greater opportunity for mother-infant interaction and contact (Hunziker and Barr, 1986; Murray, 1979).

With respect to the mother, Brody (1976) has suggested that maternal behavior during feeding serves as a model of her overall behavior toward her infant. Neverthe- less, while the feeding situation has been argued by some to reflect the quality of a mother’s interaction with her child (Spietz, 1978), surprisingly little research has been conducted on the functional significance of early feeding patterns (Carter, 1988). A notable exception is Osofsky’s (1976) demonstration that the behavioral responses of mothers and newborns during bottlefeeding were consistent with behaviors elicited during a stimulation task.

The present study was based on the assumption that infant feeding patterns are an important contributor to the developing relationship between mothers and infants. Its purpose was to investigate whether the type of feeding method and the amount of

Dow

nloa

ded

by [

Uni

vers

ity o

f C

ambr

idge

] at

06:

21 1

6 O

ctob

er 2

014

Mother-infant interactions 187

positive interactions the mother and infant display are related. Unlike previous studies that have examined interactions during feeding itself, the focus of this study was on behavior during a play episode, so as to determine the generalized effects, if any, that may be attributed to feeding regimen. It was therefore expected that breastfeeding mothers and their infants would display more positive interactions than those dyads with infants who were bottlefed at the time of observation. However, as the literature also suggests greater irritability on the part of breastfed infants, it was expected that fussing, if present, would favor the bottlefed infants. That is, infants who were still breastfed were expected to display more fussiness during Ihother-infant interaction than those who were bottlefed.

METHOD

Subjects Twenty-seven mother-infant pairs were studied and included 14 male and 13

female infants. The infants ranged in ages from 3 to 12 months, with a mean age of 8.25 months (SD = 2.75 months). All infants were born full-term and were reported by their mothers to be in good health. First born infants made up 85% of the sample. The cross- sectional sample of dyads were drawn from those families who served as pilot subjects for a study of individual differences in infant behavior. That study, which was to be longitudinal in design, required sampling infants of various ages throughout the first year of life (Stifter, 1990). All participating families resided in the predominantly middle-class university community, and were recruited from mailings sent through the local childbirth education organization.

Procedure As part of the pilot procedures, mothers and infants were observed in a 5-minute

free-play session in a laboratory that resembled a homelike setting. The mothers were instructed to play with their infants on the floor as they normally would at home. An infant seat and a basket filled with a variety of toys were available if the mother chose to use them.

The videotaped mother-infant free-play sessions were coded using a time-sampling technique. Given the mean age of the infant sample, a coding scheme developed specifically for babies approximately seven months of age was selected (Mahoney, 1989). The maternal and infant coded behaviors appear in Tables 1 and 2, respec- tively, and include items consonant with most systems for analyzing mother-infant interaction (e.g. Belsky et al., 1984; Price, 1983). At the end of each 15 second interval, all the mother and infant behaviors that had been observed were noted. Thirty percent of the videotaped episodes were coded by two observers to determine reliability, and percent agreement (agreements divided by agreements plus disagree- ments) was greater than 80% for all behaviors.

RESULTS

Behavioral differences by feeding status The present analyses were confined to maternal and infant behaviors that were

considered positive (versus neutral or negative) as directed toward the partner. This

Dow

nloa

ded

by [

Uni

vers

ity o

f C

ambr

idge

] at

06:

21 1

6 O

ctob

er 2

014

188 A. L. Kuzela et al.

Table 1. Descriptions of maternal coded behaviors (adapted from Mahoney, 1989)

Behavior Description

Play Object

Game Non-toy

Touch Affectionate

Soothing Neutral

Caregiving

Vigorous

Vocalizations Contingent

Elicitor Non-contingent

Affect Positive

Neutral

Negative

The mother introduces a toy as an object only. She may place it in front of the infant to look at or to play with without direction. The mother uses a toy in a game or rhythmic fashion. The mother plays with the infant without using a toy, e.g. singing, peek-a- boo, patty-cake, etc.

The mother shows affection toward the infant, e.g. kissing, hugging, patting, stroking, rubbing, etc. The mother pats, strokes, or rubs the infant in response to distress. The mother adjusts the infant or the infant’s clothing with no apparent intention. The mother demonstrates a caregiving action, e.g., wiping face, burping, adjusting clothing for comfort. The mother moves the infant’s limbs or uses forceful movements, e.g. tickling, shaking, pulling, etc.

The mother vocalizes in direct response to the infant’s movements or vocalization. The mother initiates a new action or interaction with the infant. Any utterance made by the mother not directed toward the infant.

The mother’s vocalizations and actions are positively displayed, e.g. rein- forcing comments, “motherese”, smiling, laughing, etc. There is no apparent inflection in the tone of voice or any obvious facial expression. The mother’s vocalizations and actions are negatively displayed, e.g. reprimands, frowns, worried looks, critical tones, etc.

approach was taken in light of our interest in behaviors that would reflect responsivity and sensitivity, which have been shown to be the most facilitative of optimal social development (Ainsworth et al., 1974; Clarke-Stewart, 1973). Maternal behaviors included all of the coded play behaviors (i.e. object, game, non-toy), most categories of touch (i.e. affectionate, caregiving, soothing, vigorous), two levels of vocalization (i.e. contingent, elicitor) and positive affect. Infant behaviors included reach toward mother, contingent vocalization, and smiling affect.

A split-half reliability analysis was undertaken to determine the internal consis- tency of the selected behaviors. In comparing the first half of the observation to the last half (Kolstoe, 1969), the summed maternal behaviors were strongly correlated (r = 0.85, p < O.OOOl), with the comparatively fewer infant behaviors approaching significance (r = 0.29).

Of the 27 mothers who participated in the study, 4 had never breastfed; 12 had breastfed for a few months, but were not at present (M = 3.75 months, SD = 1.75 months); and 11 were currently breastfeeding. Although all of the mothers who had discontinued breastfeeding had done so at least 1 month prior to their participation, it was recognized that having elected to breastfeed, and having nursed for a number

Dow

nloa

ded

by [

Uni

vers

ity o

f C

ambr

idge

] at

06:

21 1

6 O

ctob

er 2

014

Mother-infant interactions 189

Table 2. Description of infant coded behaviors (adapted from Mahoney, 1989)

Behavior Description

Affect Smiling

Neutral Fussing

Crying

ReacWGaze Mother Object Neutral

Vocalizations Contingent

Non-contingent

The infant is smiling, laughing, giggling or is exhibiting some sort of excite- ment. The infant displays no apparent expression. The infant is clearly distressed. This includes uncomfortable, tired, and cranky. The infant’s distress has developed into a full-blown cry.

The infant gazes or reaches directly toward the mother. The infant gazes or reaches directly toward a toy or other object. The infant gazes or reaches to nothing in particular.

The infant vocalizes immediately following an action or utterance made by the mother. The infant’s vocalization is not in immediate response to the mother’s utterance or action.

of months, such mother-infant dyads might resemble the currently breastfed group more than the non-breastfed group. Therefore, a proportion score based on months breastfed/months old was determined for these families, with dyads grouped as above or below 50%.

Due to the truncated nature of the categorical data, a phi coefficient was used to examine the association between the proportion scores and mother-infant behavior, derived by summing the frequencies of the a priori selected behaviors. Its lack of significant (a = 4.04) indicated that mother-infant behavior was not predicted by nursing duration, at least when using half of the caregiving history as a cutoff. Hence, for comparative purposes the 12 mothers who were no longer breastfeeding were categorized as bottlefeeders, and were combined with the never-breastfed group to total 16. A scanning of the babies by age revealed that across the two groups, namely breastfed versus bottlefed, equal numbers of infants (i.e. 3 per group) comprised the youngest (< 6 months) and oldest (> 10 months) subjects.

To determine if mothers with infants who are currently breastfed displayed more positive behaviors during the free-play sessions, a 2 x 2 fixed effect analysis of covariance was computed, with sex and current feeding method as the independent factors. As age may be related to the abilities of infants to perform certain behaviors (e.g. directed reaching, vocalizing, etc.), it was used as the covariate in these analyses.

Analyses were computed for the maternal behaviors, that is, play, touch, vocaliza- tion, and positive affect. As shown in Table 3, breastfeeding mothers touched their infants more frequently than the bottlefeeding mothers [F(4,22) = 3.85, p < 0.021, but no main effects emerged for the other maternal variables. However, an interaction effect for sex and feeding method was revealed [F(1,25) = 3.95, p < 0.051. Mothers of currently breastfed males and bottlefed females displayed more instances of positive affect than mothers of currently breastfed females and bottlefed males (p < 0.05, Newman-Keuls).

Dow

nloa

ded

by [

Uni

vers

ity o

f C

ambr

idge

] at

06:

21 1

6 O

ctob

er 2

014

190 A. L. Kuzela et al.

Table 3. Means and standard deviations of positive mother-infant behaviors by type of current feeding method and gender

Breast N = l l

Bottle N = 1 6

Male Female Male Female

M SD M SD M SD M SD

Mother behaviors Play 17.7 5.6 16.2 2.2 18.4 3.0 16.9 3.2 Touch* 6.5 5.2 4.5 4.8 3.1 2.1 5.3 4.0 Vocalizations 19.5 15.5 16.7 5.8 18.8 10.8 20.3 10.5 Positive affectt 15.2 5.1 12.0 5.8 10.8 7.9 15.5 7.0

Infant behaviors Contingent vocalizationst 2.0 2.7 1.2 2.5 0.9 0.7 4.1 3.5 Reach towardmother 5.4 3.8 3.5 1.9 2.3 2.0 5.1 3.9 Smiling affect 2.8 2.3 1.7 2.9 2.8 3.1 4.0 3.6

*Main effect of feeding. ?Sex by feeding interaction effect.

With respect to infant behavior, bottlefed infants vocalized contingently more often than breastfed infants [F(4,22) = 2.84, p < 0.051. In fact, an inspection of the raw data suggested that bottlefed infants, in general, vocalized more often, as breastfed male infants did not make any non-contingent vocalizations during the observation, a finding unlikely due to chance k2 = 6.20, p < 0.01). Neither reaching toward mother nor smiling was predicted by feeding, sex, or their interaction.

To examine the relationship between feeding method and the amount of fussiness displayed during the free-play session, a chi-square procedure was also chosen. Age was not covaried in these analyses as it was not expected to influence the amount of irritability that the infants would display in this relatively low-stress setting. Although age may be directly related to the attainment of developmental milestones, all infants were well beyond the period at which crying would be expected to peak (Brazelton, 1962). In fact, little fussing was exhibited. Nevertheless, it appeared that currently breastfed infants were more irritable as seen during the mother-infant interaction than were currently bottlefed infants k2 = 5.80, p < 0.02).

DISCUSSION

The relationship between type of feeding method and mother-infant interactions was investigated in this study. Given the limitations inherent in the sampling and design, as well as the modest results of the statistical analyses, the findings of this study are tentative at best. However, the findings do suggest that when age is covaried with sex and feeding method as independent variables, a number of significant differences may exist. Type of current feeding method seems to have an effect on the mother-infant interaction. But sex of the infant also seems to play a role in the type of interactions mother and infant pairs display.

Dow

nloa

ded

by [

Uni

vers

ity o

f C

ambr

idge

] at

06:

21 1

6 O

ctob

er 2

014

Mother-infant interactions 191

Differences between breast- and bottlefed mother-infant pairs It was expected that the currently breastfeeding mother-infant pairs would display

more positive interactions than bottlefeeding mother-infant pairs. Although not all of the comparisons significantly differentiated the groups, breastfeeding mothers touched their infants more frequently and bottlefed infants vocalized more often, but were less irritable.

Although the act of nursing may be too routinized to reveal differences in dyadic interaction within breastfeeding mother-infant pairs (e.g. Carlssonet al., 1979), it has been portrayed as clearly distinguishable from bottlefeeding (e.g. Bernal and Richards, 1970). In most reports, nursing dyads display more reciprocity in the context of feeding than do their bottlefed counterparts (Dunn and Richards, 1977; Walton and Valle- lunga, 1989). The present study did not assess the quality of interactions during feeding episodes, and it is admittedly a presumption that differences favoring breastfeed- ing dyads would have been shown.

Certainly, a myriad of other factors, not the least of which are the predisposing characteristics of mothers who elect to breastfeed in the first place (Newton, 1971; Stein et al., 1987; Switzky et al., 1979), could explain differences shown in behavior. Nevertheless, the results of this study indicate that feeding method may additionally serve to showcase differences across relationships in situations other than feeding. The finding that breastfeeding mothers touched their infants more in a play setting than did the bottlefeeders, many of whom had breastfed earlier as well, raises the possibility that interactions practiced during feeding may generalize to a contempo- raneous non-feeding context.

As predicted, infants who were currently breastfed displayed more irritability than the bottlefed infants. While at first glance this seems paradoxical, the finding is consistent with early descriptions of distress during feeding (e.g. Bernal, 1972) and the recent literature on feeding-based irritability as displayed in other situations (Barr et al., 1989; Worobey, 1990). Whether such irritability is due to hunger or activating agents in human milk, a fussing state likely provides additional opportunities for mother and infant to interact (DiPietro et al., 1987). In other words, although breastfeeding may result in a more irritable infant, the fussing may serve to promote a greater number of interactions between the mother and infant. Beyond mere frequency, however, such interactions have been viewed by some as useful in facilitating sensitive parenting, since appropriate interactive skills are being rein- forced (Carter, 1988; Walton and Vallelunga, 1989).

The role of gender in feeding and mother-infant interactions The results of the analysis of covariance suggest that currently breastfed male

infants may share a different relationship with their mothers (Heinstein, 1963), with the implication that it is somewhat stronger or more intimate than other dyadic relationships. However, behaviors displayed by the bottlefed female mother-infant dyads looked very much like the pattern for the breastfed males, with bottlefed female dyads exchanging the most affection and vocalizations. Indeed, with the exception of maternal play in the bottlefeeding dyads, currently breastfed mother-son pairs and bottlefed mother-daughter pairs exhibited more positive behaviors than did breastfed females or bottlefed males with their mothers (p < 0.05, Newman-Keuls).

While the extant literature led to our prediction that breastfed babies would fare better than bottlefed infants on all measures, the sex by feeding interaction was not

Dow

nloa

ded

by [

Uni

vers

ity o

f C

ambr

idge

] at

06:

21 1

6 O

ctob

er 2

014

192 A. L. Kuzela et al.

anticipated. By most accounts, there are few sex differences that have been found early in life (Phillips et al., 1978). Nevertheless, infants are socialized almost immedi- ately after birth, with mothers regulating the behavior of their boys or girls in a gender appropriate manner throughout their first year (Goldberg and Lewis, 1969). The association between male breastfeeding mother-infant pairs and the display of positive interactions should be further investigated to explore the possibility that males develop a different relationship with their mothers through breastfeeding. At the same time, it will be important to identify the factors that may have contributed to the behavioral pattern shown for bottlefed females. A useful approach would likely incorporate information on maternal attitudes and infant temperament, but addition- ally extend the outcome variables to examine subsequent development (Taylor and Wadsworth, 1984).

CONCLUSION

As stated previously, the limited size of the sample and the wide range in ages of the infants make the implications of these preliminary results necessarily speculative. Certainly a much larger sample of exclusively breastfed and exclusively bottlefed infants, rather than a combined group of ‘mothers who ever with mothers who never’ breastfed, would be closer to ideal. Also useful might be an inclusion of an observation of the mother and infant during an actual feeding episode, although a strength of this investigation lies in the effects seen in the context of play. While every effort was made to make the mothers feel as if they were in their own homes, some mothers may have still felt uncomfortable, and not acted as they normally would in a natural setting (Kulka et al., 1966).

The advantages associated with breast- and bottlefeeding should continue to be studied and explored. Bottlefed infants may prove to be less irritable, but regardless of feeding, opportunities for interaction need not be compromised. Since the results suggest that breastfed males resemble bottlefed females in their behavior, the fact that breastfeeding is but one contributor to the developing mother-infant relationship must be underscored. The practice of breastfeeding offers additional opportunities for intimate interaction that most certainly can be provided through other means (Carter, 1988). As the number of dual-earner families and single working mothers steadily increases (Ryan and Martinez, 1989), however, the benefits of both options remain an important topic to study.

ACKNOWLEDGEMENTS

The authors would like to thank the mothers and infants who participated, and Drs Ann Crouter and Alexander Von Eye for their helpful suggestions. This study was supported in part by a grant to John Worobey from the New Jersey Agricultural Experiment Station.

REFERENCES Ainsworth, M.D.S., Bell, S.M. and’stayton, D.J. (1974). ‘Infant-mother attachment and social

development: socialization as a product of reciprocal responsiveness of signals’. In: Richards, M.P.M. (Ed.) The Integration of a Child into a Social World, Cambridge University Press, London.

Dow

nloa

ded

by [

Uni

vers

ity o

f C

ambr

idge

] at

06:

21 1

6 O

ctob

er 2

014

Mother-infant interactions 193

Barr, R.G., Kramer, M.S., Pless, I.B., Boisjoly, C. and Leduc, D. (1989). ‘Feeding and temperament asdeterminants of early infant cryinglfussingbehavior’, Pediatrics, 84: 514521.

Bell, R.Q. (1966). ‘Level of arousal in breast-fed and bottle-fed human newborns’, Psychoso- matic Medicine, 28: 177-180.

Belsky, J., Taylor, D.G. and Rovine, M. (1984). ‘The Pennsylvania Infant and Family Develop- ment Project 11: the development of reciprocal interaction in the mother-infant dyad’, Child Development, 55: 706-717.

Bernal, J. (1972). ‘Crying during the first 10 days of life and maternal responses’, Developmental Medicine and Child Neurology, 14: 362-372.

Bernal, J. and Richards, M.P.M. (1970). ‘The effects of bottle and breastfeeding on infant development’, Journal of Psychosomatic Research, 14: 247-252.

Blumen, D.G. (1980). ‘Infant-mother bonding’. In: Freier, S. and Eidelman, A.I. (Eds), Human Milk: Its Biological and Social Value, pp. 277-282, Elsevier North-Holland, New Ylork.

Brazelton, T.B. (1962). ‘Crying in infancy’, Pediatrics, 29: 579-588. Brody, S. (1976). Patterns of Mothering, International Universities Press, New York. Carlsson, S.G., Fagerberg, H., Horneman, G.,Hwang, C.P., Larsson, K., Rodholm, M., Schaller,

J., Danielsson, B. and Gundewall, C. (1979). ‘Effects of various amounts of contact between mother and child on the mother’s nursing behavior: a follow-up study’. Znfant Behavior & Development, 2: 209-214.

Carter, C.S. (1988). ‘Patterns of infant-feeding in mother-infant interaction and stress manage- ment’. In: Field, T., McCabe, P. and Schneiderman, N. (Eds) Stress and Coping Across Development, pp. 27-46, Erlbaum, Hillsdale, NJ.

Clarke-Stewart, K.A. (1973). ‘Interactions between mothers and their young children: charac- teristics and consequences’, Monographs of the Society for Research in Child Development,

DiPietro, T.A., Larson, S.K. and Porges, S.W. (1987). ‘Behavioral and heart-rate pattern differences between breast-fed and bottle-fed neonates’, Developmental Psycholcgy, 23: 467-474.

Dunn, J.B. and Richards, M.P. (1977). ‘Observations on the developing relationship between mother and baby in the neonatal period’. In: Schaffer, H.R. (Ed.) Studies in Mother--Infant Interaction, Academic Press, New York.

Goldberg, S. and Lewis, M. (1969). ‘Play behavior in the year-old infant: early sex differences’, Child Development, 40: 21-32.

Guthrie, H. (1989). Introductory Nutrition, Times Mirror/Mosby, St. Louis. Heinstein, M.I. (1963). ‘Behavioral correlates of breast-bottle regimes under varying

parent-infant relationships’, Monographs of the Society for Research in Child Development, 28(4).

Holt, G. and Wolkind, S. (1983). ‘Early abandonment of breast feeding: causes and effects’, Child Care, Health, and Development, 9: 349-355.

Hunziker, U.A. and Barr, R.G. (1986). ‘Increased carrying reduces infant crying: a randomized controlled trial’, Pediatrics, 77 641-648.

Jones, D.A. (1986). ‘Attitudes of breast-feeding mothers: a survery of 649 mothers’. Social Science and Medicine, 23: 1151-1156.

Kolstoe, R.H. (1969). Introduction to Statistics for the Behavioral Sciences, Dorsey Press, Homewood, IL.

Kulka, A.M., Walter, R.D. and Fry, C.P. (1966). ‘Mother-infant interaction as measured by simultaneous recording of physiological processes’, Journal of the American Academy of Child Psychiatry, 5: 496.

Mahoney, N. (1989). ‘The effects of prematurity on seven-month mother-infant interaction’. Unpublished master’s thesis, University of Maryland, College Park.

Martin, J. and Monk, J. (1982). Infant Feeding 1980, OPCS Social Survey Division, London. Martinez, G. and Krieger, F. (1985). ‘1984 milk-feeding patterns in the United States’,

Murray, A.(1979). ‘Infant crying as an elicitor of parental behaviour: An examination of two

Newton, N. (1955). Maternal Emotions, Hoeber, New York. Newton, N. (1971). ‘Psychologic differences between breast and bottle feeding’, American

38: 6-7.

Pediatrics, 76: 1004-1008.

models’, Psychological Bulletin, 8 6 191-215.

Journal of Clinical Nutrition, 24: 993-1004.

Dow

nloa

ded

by [

Uni

vers

ity o

f C

ambr

idge

] at

06:

21 1

6 O

ctob

er 2

014

194 A. L. Kuzela et al.

Osofsky, J.D. (1976). ‘Neonatal characteristics and mother-infant interaction in two observa- tional studies’, Child Development, 47: 1138-1147.

Phillips, S., King, S. and DuBois, L. (1978). ‘Spontaneous activities of female versus male newborns’, Child Development, 44: 182-186.

Price, G.M. (1983). ‘Sensitivity in mother-infant interactions: the AMIS scale’, Znfant Behavior & Development, 6 353-360.

Richards, M.P.M. and Bernal, J.F. (1971). ‘An observational study of mother-infant interac- tion’. In: Blurton-Jones, H. (Ed.) Ethological Studies of Child Behavior, Cambridge Univer- sity Press, Cambridge.

Ryan, A.S. and Martinez, G.A. (1989). ‘Breast-feeding and the working mother: a profile’, Pediatrics, 8 3 524-531.

Shand, N. (1981). ‘The reciprocal impact of breast-feeding and culture form on maternal behavior and infant development’, Journal of Biosocial Science, 13: 1-17.

Spietz, A.L. (1978). ‘Why look at the feeding?’ In: Barnard, K. (Ed.) The Nursing Child Assessment Feeding Scales, pp. 5-16, NCAST-University of Washington, Seattle.

Stein, A., Cooper, P., Day, A. and Bond, A. (1987). ‘Social psychiatric factors associated with the intention to breastfeed’, Journal of Reproductive and Infant Psychology, 5: 165-171.

Stifter, C.A. (1990). ‘Infant colic and its effect on parent perception and later behavior’, Infant Behavior & Development, 13: Special ICIS Issue, 207.

Switzky, L., Vietze, P. and Switzky, H. (1979). ‘Attitudinal and demographic predictors of breast-feeding and bottle-feeding behavior by mothers of six-week-old infants’, Psychologi- cal Reports, 45: 3-14.

Taylor, B. and Wadsworth, J. (1984). ‘Breastfeeding and child development at five years’, Developmental Medicine and Child Neurology, 26 73-80.

Walton, M.D. and Vallelunga, L.R. (1989). ‘The role of breast-feeding in establishing early mother-infant interaction, Abstracts of the Society for Research in Child Development, 7: 393.

Wiesenfeld, A.R., Malatesta, C.Z., Whitman, P.B., Grandose, C. and Uili, R. (1985). ‘Psy- chophysiological response of breast- and bottle-feeding mothers to their infant’s signals’, Psychophysiology, 22: 70-85.

Woollett, A. (1987). ‘Who breastfeeds? The family and cultural context’, Journal of Reproduc- tive and Infant Psychology, 5: 127-131.

Worobey, J. (1989). ‘Mother-infant interaction: protocommunication in the developing dyad. In: Nussbaum, J.F. (Ed.) Life-span Communication: Normative Processes, pp. 7-25, Erlbaum, Hillsdale, NJ.

Worobey, J. (1990). ‘Method of feeding and early reactivity’, Infant Behavior & Development, 13: Special ICIS Issue, 208.

Dow

nloa

ded

by [

Uni

vers

ity o

f C

ambr

idge

] at

06:

21 1

6 O

ctob

er 2

014