Feeding behaviour problems in infants born preterm - a psychological perspective. Preliminary report*

Problemy w zachowaniach związanych z karmieniem u niemowląt urodzonych przedwcześnie - perspektywa psychologiczna. Doniesienie wstępne

Grażyna Kmita1,2, Wanda Urmańska2, Eliza Kiepura2, Krystyna Polak3
1Department of Clinical Psychology of Child and Family
Head: Prof. M. Zalewska
Faculty of Psychology, University of Warsaw
Dean: Prof. E. Czerniawska
2Early Psychological Intervention Department
Head: G. Kmita, PhD
3Neonatology and Neonatal Intensive Care Clinic
Head: Prof. E. Helwich, MD, PhD
Institute of Mother and Child
Director: S. Janus

* This project was supported by the Ministry of Science and Higher Education grant N N 106045734

Abstract
Aim: The study was aimed at exploring feeding behaviour problems reported by parents of premature infants during the first 12 months corrected age. Material and methods: A subsample of families enrolled in a larger, prospective project on psychological and biological predictors of self-regulation in preterm children participated in the study. The material consisted of data collected from 40 families of preterm infants in the first and fourth and then at six and twelve months corrected age. The children were divided into two groups according to their gestational age: group 1 – 22 children born before 29th week (mean gestational age 26 Hbd and mean birth weight 905 g) and group 2 – 18 children born between 29th and 34th week (mean gestational age 31 Hbd and mean birth weight 1531 g). Semi-structured interviews and daily activity diaries were used. Qualitative, exploratory analysis of parental descriptions of child’s feeding behaviour was performed. Results: No feeding behaviour problems were reported in 31.8% infants in group 1 and 44.4% in group 2, whereas chronic feeding behaviour problems – in the case of 5 infants in group 1 (22.7%) and just in one child in group 2 (5.6%). There was a significant association between “gastrointestinal complications of prematurity” and parental reports of feeding behaviour problems at two and more evaluation times. No relationship was found with such variables as: group, child’s gender, method of feeding, mother’s postnatal depression, or other complications of prematurity. Six major categories of feeding problems were identified: 1) early regulatory problems, 2) pain and/ or excessive spitting, 3) insufficient weight gain, 4) poor eater, 5) difficulties introducing new taste or consistency, and 6) difficulties with introducing self-feeding. These categories occurred with varying frequencies depending on the child’s gestational age and the assessment time. Conclusion: The results point to an interesting diversity and dynamics of feeding behaviour difficulties in babies born preterm. It was shown that extremely low gestational age as well as gastrointestinal complications of prematurity may contribute to increased parental reports of feeding behaviour difficulties. Further research is needed to disentangle divergent underlying mechanisms of different feeding behaviour problems and describe possible challenges they may imply to the child, parents and their relationship.

Key words: infant, premature, feeding behaviour, parents

Streszczenie
Cel: Celem pracy była analiza eksploracyjna problemów w zachowaniach związanych z karmieniem, zgłaszanych przez rodziców niemowląt urodzonych przedwcześnie. Materiał i metoda: Badaniami objęto podgrupę rodzin uczestniczących w większym projekcie na temat biologicznych i relacyjnych uwarunkowań samoregulacji u dzieci urodzonych przedwcześnie. Materiał badawczy stanowiły nagrania semi-ustrukturowanych wywiadów z rodzicami i dziennika aktywności dziecka 40 niemowląt. Dzieci zostały podzielone na dwie grupy: 22 niemowlęta urodzone przed 29 tygodniem ciąży (średni wiek ciążowy 26 Hbd i średnia masa urodzeniowa 905 g) – grupa 1, oraz 18 niemowląt urodzonych pomiędzy 29 i 34 tygodniem (średni wiek ciążowy 31 Hbd i średnia masa urodzeniowa 1531 g) – grupa 2. Materiał zbierano w pierwszym i czwartym miesiącu a następnie na etapie 6 i 12 miesięcy wieku korygowanego. Wyniki: U 7 (31,8%) dzieci z grupy 1 oraz u 8 (44,4%) dzieci z grupy 2 rodzice nie zgłaszali żadnych problemów związanych z karmieniem. Problemy długotrwałe, o większym nasileniu zgłosili rodzice pięciorga dzieci z grupy 1 (22,7%) i tylko u jednego dziecka z grupy 2 (5,6%). Stwierdzono istnienie istotnej zależności pomiędzy wystąpieniem gastrologicznych powikłań wcześniactwa a zgłaszaniem co najmniej na dwóch spotkaniach problemów związanych z karmieniem. Nie udało się odrzucić hipotezy zerowej o braku związku pomiędzy zgłaszaniem problemów co najmniej na 2 spotkaniach a takimi zmiennymi jak: grupa, płeć dziecka, sposób karmienia, wystąpienie u matki depresji poporodowej czy inne powikłania wcześniactwa. Empirycznie wyodrębniono 6 kategorii problemowych zachowań związanych z karmieniem o zróżnicowanych częstościach na poszczególnych etapach badania i w zależności od wieku ciążowego dziecka. Były to: 1) wczesne trudności regulacyjne, 2) dolegliwości bólowe i/lub nadmierne ulewanie, 3) za mały przyrost masy ciała, 4) niejadek, 5) trudności z wprowadzaniem nowych smaków/konsystencji, 6) trudności z podejmowaniem prób samodzielnego jedzenia. Wnioski: Wyniki wskazują na interesujące zróżnicowanie zgłaszanych przez rodziców trudności w zachowaniach związanych z karmieniem u dzieci urodzonych przedwcześnie. Wskazują również na to, że ekstremalnie mały wiek ciążowy noworodka i gastrologiczne powikłania wcześniactwa mogą mieć istotne znaczenie dla zgłaszania przez rodziców problemów związanych z karmieniem dziecka. W dalszych badaniach warto podjąć próbę opisania zróżnicowanych patomechanizmów zaburzeń ze strony układu pokarmowego występujących u niemowląt przedwcześnie urodzonych oraz wyzwań jakie problemy związane z karmieniem mogą stanowić dla rodziców, dla dziecka i ich relacji.

Słowa kluczowe: wcześniak, zachowania związane z karmieniem, rodzice

INTRODUCTION
Feeding constitutes one of the early developmental tasks that are essential for the newborn and infant survival. According to Herman and Polivy (1), it can be regarded as a highly regulated activity requiring multi-level coordination of different biological/physiological, behavioural and social systems in order to serve its biological function in an efficient way. In terms of behavioural systems, feeding requires well coordinated and adjusted to the child’s signals of hunger and satiation behaviours on the part of a caregiver (2). No neonate and no infant could do without an adult (usually mother or mothering figure) providing food (breast milk or infant formula) in the course of everyday social interactions. It is beyond the scope of this paper to discuss complex neurological and physiological foundations of the process of feeding. Instead, the focus will be on psychological phenomena related to feeding and behavioural aspects of feeding difficulties and disorders in the youngest children. The very notion of “feeding disorder” is quite complex with different definitions depending on the author’s specialty(pediatrics, physiotherapy, psychology, psychiatry, etc.). For the purposes of this paper a definition proposed in the Diagnostic Classification: 0-3R (3, 4) is adopted. According to DC:0-3, the diagnosis of feeding behaviour disorders of infancy and early childhood “should be considered when an infant or young child has difficulty establishing regular feeding patterns – that is, when the child does not regulate his feeding in accordance with physiological feelings of hunger and fullness” (3, p. 35). Additional criteria are also emphasized including the absence of such precipitants as hunger, trauma, prolonged separation and structural/organic/medical problems that compromise the child’s ability to eat or digest food. In the case of medical problems it is recommended not to give a primary diagnosis of the feeding behaviour disorder until it becomes clear that symptoms persist despite the fact of having cured the initial problem of structural or organic nature (3, 4). The overall prevalence of severe and chronic feeding behaviour disorders is estimated to be 1-2%, while minor difficulties occur in 25-35% of young children (2). Six specific subtypes of feeding behaviour disorders have been distinguished: feeding disorder of state.
regulation, feeding disorder of caregiver – infant reciprocity, infantile anorexia, sensory food aversion, feeding disorder associated with concurrent medical condition, feeding disorder associated with insults to the gastrointestinal tract (3, 4, 5, 6). The respective diagnostic criteria are beyond the scope of this paper and can be found elsewhere (3, 4, 5). It is a widely accepted fact that feeding can be particularly challenging to premature infants and their families (7). Preterm birth with all its consequences often inflicts considerable risks or challenges to the process of feeding (7). With the developments of medical technology babies survive long before they are ready to digest food, breathe on their own, suckle or be able to co-ordinate breathing, sucking and swallowing which means that they may need total parenteral nutrition, then gastric tube feeding and only gradually learn how to eat independently when bottle-nursed or breastfed (7). Child’s neurological immaturity and specific oral experiences may have long-term consequences not even to mention the impact of severe gastrointestinal complications of prematurity such as necrotizing enterocolitis, intestinal perforation, etc. Witnessing the above mentioned early problems may exert long-lasting effects on how parents perceive their child and interact with him/her, which may in turn affect feeding processes in later months of life. Many parents of premature infants attribute special meaning to child’s appropriate weight gain, effective feeding and competent eating. Apart from that, less optimal patterns of social interactions are often reported as characteristic for many mother- preterm child dyads (8).
The aim of this study was to explore parental experience of feeding behaviour problems in preterm infants up to the corrected age of 12 months. The following questions were asked:
1. Are feeding behaviours reported as problematic by parents of preterm infants?
2. Are feeding behaviour problems persistent over the course of the first 12 months child’s corrected age?
3. Are feeding behaviour problems reported by the parents related to the child’s gestational age, method of feeding, mother’s postnatal depression, and different medical complications of prematurity?
4. What categories of feeding behaviour problems can be discerned from parental reports and what their dynamics is over the course of infancy?

METHOD
Subjects
This study was conducted on a subsample of families enrolled in a larger, prospective project on psychological and biological predictors of self-regulation in preterm children. Out of 90 participating families 40 (66.7% of the original sample of premature children) were selected according to the following criteria: gestational age below 35 weeks (Hbd) and complete data from at least four scheduled meetings with the family available by mid November 2010. The children were divided into two groups according to their gestational age: group 1 – 22 children born before 29th week and group 2 – 18 children born between 29th and 34th week. The families were recruited in two different tertiary care hospitals in Warsaw from July 2008 till December 2009. For each child both parents signed the informed consent forms, and willingness of both mother and father to participate in the study was the primary criterion of inclusion. Exclusion criteria were teenage parenting and congenital malformations/genetic syndromes. Sample characteristics are presented in table I.

MATERIAL AND PROCEDURE
The study comprised 4 meetings with each family – in the first and fourth month corrected age at home and then at six and twelve months – at a baby lab. For purposes of the analyses presented in this paper the material comprised semi-structured interviews with both parents on topics related to parent-child relationship and child development, including feeding behaviour concerns. Apart from that a specially elaborated diary of everyday activities was collected approximately a week before the last meeting. The diary consisted of 24 hours records of child’s activities for three days and additional open-ended questions about child’s feeding behaviour, bedtime practices,play, etc. Medical records of each participating child were analysed by a neonatologist and a neonatal nurse. Child’s developmental status and temperament as well as parental mood at 3 and 6 month meeting were also controlled for.
Data analysis
Feeding behaviour was considered one of a number of indices of child’s self-regulatory competence. Qualitative, exploratory analysis was performed. Data obtained during each of the meetings were inspected and all information regarding feeding was retrieved. In the interviews utterances and passages describing the child’s feeding behaviour (including problematic behaviour) and feeding interactions were identified, analysed thematically and categorised. Thus the categories were empirically derived. Categorisation was done by two independent raters with inter-rater agreement measured by Cohen’s kappa as high as 0.9084 (with 0.95 Confidence Interval between 0.8463 and 0.9705; Vassar College Kappa Calculator by R. Lowry was used). Proportion of agreements for the category “feeding behaviour difficulties+” (FBD+), i.e. the sum of feeding problems reported by parents in all subcategories congruently categorised by the two judges(CFBD) divided by the sum of CFBD and the number of problems in all subcategories that were not categorised congruently, was 0.8961(0.95 CI from 0.8003 to 0.9509). For statistical analysis STATISTICA PL 8.0 was used.

RESULTS
Data on feeding behaviour problems reported by the parents are shown in table II and presented according to child’s gestational age in the following intervals: 22-24, 25-26, 27-28, 29-30, 31-32 and 33-34 weeks. The first three intervals represent group 1, whereas the remaining three intervals – group 2. As can be easily discerned from table II, parents of 15 children (7 from group 1, and 8 from group 2, which comprised 31.8% and 44.4% respectively) reported no problems with feeding behaviour at all. In the case of 19 subjects the problems were reported during one or two meetings with the family and were rather mild (10 infants in group1 and 9 – in group 2, 45.5% and 50.0% respectively).
Only 6 children: 5 in group 1 (22.7%) and 1 in group 2 (5.6%) were reported to exhibit feeding behaviour di­culties of more severe and persistent nature (i.e. observed on at least three meetings or – as in the case of one child of group 1 – very severe on two consecutive ones). Out of the 5 children of group 1, diagnosed as having more severe feeding di­culties throughout the ‑rst year of life, two had periventricular leucomalacia (PVL) and were diagnosed to have cerebral palsy (one of those subjects had also IVH grade IV). One child was diagnosed with intrauterine growth retardation, two had severe gastrointestinal complications of prematurity (NEC and intestinal perforation) and one – gastroesophageal reux. All were also diagnosed as having bronchopulmonary dysplasia (BPD). In the only child with chronic feeding problems in the second group, severe gastrointestinal complications of prematurity in the neonatal period were observed and intrauterine growth retardation. At the corrected age of 12 months 3 children with chronic problems received developmental index (DI) of 5 and more stens in Infant Developmental Scale (9) (DI within an average range – 2 children of group 1 and DI above the average – 1 girl from group 2). In the case of three remaining children, delayed development was observed (developmental index of 4 stens and less; in the case of one boy – only functional assessment). Interestingly, as many as 28.6% (4 out of 14) children born at or before 26th gestational week were perceived by their parents as having chronic feeding difficulties, as compared to only 12.5% (2 out of 16) born between 27 and 30 weeks and 0% between 31 and 34 weeks.
From parental perspective, even relatively mild difficulties but lasting for a substantial amount of time as expressed by their presence on at least two of the scheduled meetings (i.e. for two-three months at the minimum), may constitute a major challenge to the quality of family life. There were 11 families meeting this criterion, which comprised 27.5% of all participants, 6 in group 1 (27.3%) and 5 in group 2 (27.8%). Relevant data are presented in table III. Presence of problems on at least two scheduled meetings as opposed to no problems at all or problems reported on just one meeting (dichotomized, nominal variable) was significantly related to dichotomous variable “gastrointestinal complications of prematurity” (necrotizing enterocolitis, gastrointestinal perforation, etc.) (Chi˛yat=5.177, df=1, p=0.02289). No such relationship was found with the following variables: group, child’s gender, method of feeding, mother’s postnatal depression, or other complications of prematurity (see table III). One point requires an explanation here. 20 children were breastfed at least to the corrected age of 6 months (10 in each of the groups, 45.5% of group1 and 55.6% of group 2), but in the case of many breastfed babies of group 1 this way of feeding was supplemented with formula feeding. As to the remaining 20 infants who were formula fed (12 in group1 and 8 in group2, 54.5% and 44.4% respectively), instances of bottle feeding with mother’s expressed milk were also included (3 babies from groups 1 and one child from group 2).
In the process of qualitative analysis twelve groups of difficulties reported by the parents were empirically discerned, and then in the process of further analysis, six broader categories of problems were identified. They were as follows: 1) “early regulatory problems”, i.e. initial problems with the quality of sucking- swallowingbreathing coordination and mastering each of the three basic processes as well as regulating own state of arousal; in this broader category parents reported child’s poor sucking, easily getting tired when being fed, instances of apnea, necessity to take additional measures in order to calm the baby so that he/she can be fed, etc., 2) painful crying during or after feeding, colic, excessive spitting and vomiting, 3) worries about child’s weight gain, 4) complaints that the child does not eat enough or refuses to be fed; in this category instances of prolonged feeding sessions and very small food portions were also included, 5) difficulties related to introducing new, solid foods and new textures and tastes (refusal, vomiting, difficulties with swallowing or biting and chewing food, etc.), 6) refusal to try to eat independently. The last two categories taken together could easily be regarded as “transition problems”, i.e. difficulties in a transition from infantile to more adult-like food and eating. The distribution of the six categories with reference to gestational age is provided in table II, whereas relative frequencies of children with problems of each of the six categories, at each of the four scheduled meetings is given in figure 1. What was interesting, the first and second broad categories were typical for the first month corrected age and sometimes were also noted in the two following months, whereas the 5th and 6th categories were mainly observed at the end of the study which can be easily explained developmentally (see table II and figure 1). The 5th category was often observed at the 6 months meeting but at that time was not treated as a sign of disordered behaviour and therefore these instances had been excluded. As to categories 3 and 4, such complaints were reported at all scheduled meetings, although small amounts of food and longer feeding time was more characteristic of the younger infants. In the case of one girl from group 1 quite an opposite problem was noted at the corrected age of 6 months, namely gaining too much weight according to pediatric evaluation, which was nonetheless differently perceived by the parents who continued to feed the child when asleep and still used apnea monitor. It is worth emphasizing that the smallest number of parental concerns was reported at the 3 months meeting, whereas the biggest – at the first and last meeting (see table II). Taking into account the child’s gestational age, there was a clear distinction between parental reports in the case of children born before 29th week and during later weeks of pregnancy (group 1 versus group 2). As shown in table II, except for the two children born extremely early (22-24 weeks), children born between 25 and 28 weeks were reported to exhibit not only “early regulatory” and “transition” problems as in the case of children of group 2, but also relatively more often – difficulties of categories 2, 3 and 4. This means that their parents were quite concerned with child’s weight gain, worried that their child was a poor eater and might have interpreted their child’s cry as a sign of abdominal pain. In addition, the analysis of parental narratives revealed that feeding is attributed special meaning in many families of extremely premature infants and feeding behaviour difficulties may greatly affect family interactions and well-being in general.

DISCUSSION
The results of this study clearly show that a substantial percentage of infants born preterm in our sample presented some kind of feeding behaviour difficulties in the first year of life, at least as experienced by their parents. This is in line with the results of other studies (7). Also in congruence with other reports (10), more severe and pervasive problems were observed in children with co-existing gastrointestinal or neurological conditions. Interesting differences occurred in the frequency and persistence of different categories of feeding behaviour problems depending on child’s gestational age. Quite surprisingly, in two infants with lowest gestational age only minor feeding problems were reported at one evaluation time (one child in the first and the other in the fourth month corrected age). This can be explained by either their exceptionally good health status as for the considered gestational week, or by specific experience of the parents who might perceive their child’s functioning in terms of a miracle and attribute different meaning to feeding behaviours than parents of children with higher chances for survival. In the case of other children born before 29th gestational week, definitely more persistent problems were identified than in children born between 29 and 34 weeks. This can be easily attributed to such factors as higher frequency of gastrointestinal, neurological and pulmonary complications in extremely premature babies, their specific feeding experiences, immaturity affecting early social interactions (including feeding interactions), but also traumatic experiences of parents, for whom feeding a baby efficiently means saving his life long after any threat to survival exists.
Qualitative analysis showed interesting changes in the reported problems over the first twelve months after expected date of the child’s birth. The first of the six major categories distinguished in this study covers a range of problems that can be regarded as signs of transient regulatory difficulties resembling DC:0-3 category of “feeding behaviour disorder of state regulation” (3, 4, 5), although in most cases of the sample under study it probably does not reach the level of a “disorder” in terms of neither intensity nor duration. What is more, the dynamics of change in the manifestations of feeding behaviour problems in the sample may lead one to a conclusion that after a relatively less problematic time “captured” at the 3 months meeting the next challenge to the developing “feeding regulatory system” is the time of introducing new foods, and especially new textures of food. If the difficulties of the child are limited to these of category 1 and later on 5 and even 6 then it is quite likely that they reflect only transient, regulatory problems as part of managing new developmental tasks. As to category 4, i.e. “refusal to eat or eating too little”, it is close to infantile anorexia (3, 4, 5, 11), especially when accompanied by insufficient weight gain and is present for a substantial time. This category may imply deregulation at the level of parent-child interactions, which would be worth addressing in future studies. Although it is widely recognized that feeding difficulties in prematures are best managed by a multidisciplinary team (10), especially in the case of the longer-lasting difficulties of the above described nature without underlying medical conditions the use of finely attuned psychological intervention focused on interactive behaviours may be worth recommendation.
Finally, it is necessary to point out the limitations of the presented study. First, it should be treated as a preliminary report as the original broader project is still in progress (as of December 2010). The sample size is small and the group may be not representative on such dimensions as parents’ educational level and socio-economic status, which seem to be higher than average for the population of families of preterm children. In addition, our sample was also exceptional in terms of high fathers’ involvement in their children’s lives. Our results are based on parental reports which can be quite biased and may not reflect actual “feeding behaviour disorders” as diagnosed by a professional team. Apart from that, feeding was not the main focus of the original project, which means that questions regarding feeding behaviour and practices were asked in the context of other developmentally appropriate tasks and challenges. This can be a disadvantage as some parents might have underreported, but on the other hand – can be an advantage as only real and not “suggested” parental concerns were identified. It should be also borne in mind that this was a relatively healthy sample. Further research is needed on children with identified feeding behaviour disorders in order to check how many of them are prematures. As the reasons for feeding behaviour difficulties in infancy may reside within a child, his/ her parents or specific features of their interactive behaviours, future analyses should be focused not only on parental reports but also on the characteristics of parent-child interactions.

CONCLUSIONS
The results of this study based on parental reports collected prospectively over the course of infancy point to interesting diversity and dynamics of feeding behaviour difficulties in babies born preterm. It was shown that extremely low gestational age as well as gastrointestinal complications of prematurity may contribute to increased parental reports of feeding behaviour difficulties. Our hypothesis to be checked in further studies is that different categories of problems described in this paper may represent divergent underlying mechanisms and challenges to a child, parents and their relationship. An approach based on treating feeding and eating processes as complex multilevel regulatory tasks seems to be very promising.

Acknowledgments
The authors would like to express their gratitude to all families participating in the project. Special thanks go to members of the research team, and particularly to: Bozena Cieslak-Osik, Dorota Lewandowska, and Magda Winiarska-Smoczynska, and to students: Katarzyna Badziak, Aleksandra Jezewska, Magdalena Kania, Anna Majos, Alicja Niedzwiecka, Justyna Ołdak, and Karolina Suchocka.

REFERENCES
1. Herman C.P., Polivy J.: The self-regulation of eating. Theoretical and Practical Problems. In: R.F.Baumeister, K.D. Vohs (eds.). Handbook of Self-Regulation. Research, Theory and Applications. The Guilford Press, New York, 2007.
2. Liu Y.H., Stein M.T.: Feeding behaviour of infants and young children and its impact on child psychosocial and emotional development. In: Tremblay R.E., Barr R.G., Peters R. (eds.) Encyclopedia on Early Childhood Development (online). Montreal, Quebec: Centre of Excellence for Early Childhood Development; 2005:1-7. Available at: http:// www.child-encyclopedia.com/documents/Liu-SteinANGxp. pdf. Accessed (11 October 2010).
3. Zero to Three. Diagnostic classification of mental health and developmental disorders of infancy and early childhood: Revised edition (DC:0-3R). Zero to Three Press, Washington DC, 2005.
4. Klasyfikacja Diagnostyczna DC:0-3R. Klasyfikacja diagnostyczna zaburzeń psychicznych i rozwojowych w okresie niemowlęctwa i wczesnego dzieciństwa. Oficyna Wydawnicza „Fundament”, Warszawa, 2007.
5. Chatoor I., Getson P., Menvielle E., Brasseaux C., O’Donnell R., Rivera Y.: A feeding scale for research and clinical practice to assess mother–infant interactions in the first three years of life. Infant Ment Health J, 1997, 18 (1), 76- 91.
6. Jagielska G.: Zaburzenia odżywiania u niemowląt i małych dzieci. Przegląd Lekarski, 2009, 66 (1-2), 110-113.
7. Dodrill P., Donovan T., Cleghorn G., McMahon S., Davies P.S.W.: Attainment of early feeding milestones in preterm neonates. J Perinatol, 2008, 28, 549-555.
8. Schmucker G., Brisch K-H., Kohntop B., Betzler S., Osterle M., Pohlandt F., Pokorny D., Laucht M., Kachele H., Buchheim A.: The influence of prematurity, maternal anxiety, and infant’s neurobiological risk on mother-infant interactions. Infant Ment Health J, 2005, 26, 5, 423-441.
9. Matczak A., Jaworowska A., Ciechanowicz A., Fecenec D., Stanczak J., Zalewska E.: Dziecięca Skala Rozwojowa DSR. Pracownia Testów Psychologicznych. Warszawa, 2007.
10. Schädler G., Süss-Burghart H., Toschke A. M., von Voss H., von Kries R.: Feeding disorders in ex-prematures: causes – response to therapy – long term outcome. Eur. J. Pediatr., 2007, 166, 803-808.
11. Ammaniti M., Lucarelli L., Cimino S., D’ Olimpio F., Chatoor I.: Maternal Psychopathology and Child Risk Factors in Infantile Anorexia, Int. J. Eat Disord., 2010, 43, 233-240.

Adres do korespondencji / Address for correspondence::
Grazyna Kmita
Institute of Mother and Child
ul. Kasprzaka 17a, 01-211 Warszawa
grazyna.kmita@imid.med.pl
grazyna.kmita@psych.uw.edu.pl