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Breastfeeding behavior and related factors in low-income and ethnically diverse mother-infant dyads

ProQuest Dissertations and Theses, 2009
Dissertation
Author: Therese Hong-Dung Doan
Abstract:
Breastfeeding (BF) is a health-promoting behavior and exclusive BF has proven economic and ecologic benefits to individuals and societies. Yet Healthy People 2010 BF objectives for exclusive BF remain unmet and prevalence is lowest for low-income populations. The purpose of this descriptive longitudinal study of 126 predominantly low income and ethnically diverse mother-infant dyads was to compare maternal and infant factors associated with nighttime BF behavior between exclusive BF dyads and supplemented dyads. Descriptive statistics, repeated measures ANOVA, independent t-tests, and Chi-square tests were used for analysis. BF behavior was categorized as either (1) exclusive BF , defined as 100% BF or breastmilk feeding on all three nights, or (2) supplementation , defined as any formula during any of the three nights. Compared to women in supplementation (n=59), women in exclusive BF (n=67) were older, more likely Caucasian, working at 36 weeks pregnant but not working at 1 month postpartum, in a relationship, and getting less help with baby at night. There was no group difference in objective sleep at the last month of pregnancy assessment. At one month postpartum, women in the supplementation group averaged 30 minutes less night sleep compared to women in the exclusive BF group. Compared to infants who were supplemented (n=54), infants who were exclusively breastfed (n=66) were significantly more likely to room-in with mothers in hospital and receive a home visit. They were statistically larger at birth, although the difference in size may not be clinically relevant. Assessment of sleep in new mothers is important for BF maintenance and more effort is needed to promote exclusive BF among younger women, African Americans and women of Asian descent. Rooming-in practice in the hospital after birth should be encouraged, as it was significantly associated with exclusive BF behavior at one month postpartum in this diverse sample of new families. Future research using a qualitative approach would be ideal to discover how nighttime feeding for new mothers evolves over time, their motivation for BF, and their network of influence in support of BF behavior. Findings from qualitative research will be useful in developing an effective intervention for BF maintenance.

Table of Contents Title Page .......................................................................................................................i Copyright ......................................................................................................................ii Acknowledgements ...................................................................................................... iii Abstract ........................................................................................................................ v Table of Contents ........................................................................................................ vii

CHAPTER ONE ........................................................................................................... 1   Purpose ............................................................................................................................. 3   Theoretical Approaches in Human Lactation ................................................................... 4   The Role of Theory .......................................................................................................... 6   Components of Theory ..................................................................................................... 6   Conceptualization of BF Maintenance ............................................................................. 8   Breast .................................................................................................................... 8   Feed ....................................................................................................................... 9   Breastfeeding ........................................................................................................ 9   Breastfeeding Maintenance ................................................................................. 10   Evaluation of Social Contextual Model for BF Maintenance ........................................ 10   Paradigmatic Origin ............................................................................................ 11   Model Description .......................................................................................................... 12   Sociodemographic Characteristics ...................................................................... 12   Modifying Conditions ......................................................................................... 13   Mediating Mechanisms ....................................................................................... 13   Modifying versus Mediating ............................................................................... 14   Health Behaviors & Health Outcomes ................................................................ 15   Culture................................................................................................................. 15   Critique of Social Contextual Model .............................................................................. 15   Lactation Physiology Theory ......................................................................................... 17   Lactogenesis ........................................................................................................ 17   Galactopoiesis ..................................................................................................... 18   The Role of Hormones ........................................................................................ 18   The Clinical Importance of the Fourth Trimester ........................................................... 20   Proposed Conceptual Model for BF Maintenance ......................................................... 22   Modifying Conditions ......................................................................................... 22   Mediating Mechanisms ....................................................................................... 25   Culture................................................................................................................. 26   Summary ......................................................................................................................... 30   CHAPTER TWO: Interventions for BF Maintenance ................................................ 32   Abstract ........................................................................................................................... 32   The State of the Science on BF Maintenance ................................................................. 36   Search Strategy ................................................................................................... 36   Results ................................................................................................................. 37   Organization of the Review ............................................................................................ 37   Individual Factors and Early BF Success ....................................................................... 38  

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Dyad Interventions .............................................................................................. 39   Maternal Factors: Interventions for Breast and Nipple Pain .............................. 41   Infant Factors: Artificial Nipples and Sleep Location ........................................ 43   Interpersonal Factors and Support for BF Maintenance ................................................. 46   Peer Support ................................................................................................................... 48   Professional Support ....................................................................................................... 50   Perception of Mothers and Fathers ..................................................................... 52   Organizational Factors and BF Maintenance ................................................................. 53   Baby-Friendly Hospital Initiative ....................................................................... 54   Special Supplemental Nutrition Program for Women, Infants and Children (WIC) ............................................................................................................................. 54   Discussion ....................................................................................................................... 58   CHAPTER THREE: BF Behavior and Sleep of New Mothers .................................. 63   Abstract ........................................................................................................................... 63   Introduction .................................................................................................................... 64   Participants & Design ..................................................................................................... 66   Measures ......................................................................................................................... 66   BF Behavior ........................................................................................................ 66   Sociodemographic Characteristics ...................................................................... 67   Data Analysis .................................................................................................................. 69   BF Behavior .................................................................................................................... 71   Sample Description ........................................................................................................ 71   Objective Sleep ............................................................................................................... 72   Perception of Sleep ......................................................................................................... 73   Discussion ....................................................................................................................... 74   CHAPTER FOUR ....................................................................................................... 78   Infant Factors Associated with Nighttime Feeding Behavior ........................................ 78   Method ............................................................................................................................ 83   Procedure ............................................................................................................ 83   Results ............................................................................................................................ 86   Sample Description ............................................................................................. 86   Infant Factors Associated with Night-time Feeding Methods ............................ 88   Discussion ....................................................................................................................... 89   CHAPTER FIVE ........................................................................................................ 93   Clinical Implications .................................................................................................... 100   References ................................................................................................................. 101

List of Tables Table 1 - Summary of Theories Frequently Used in Human Lactation Research ........ 129   Table 2 - Critique of Theory Using Criteria Proposed by Meleis (2005) .................... 130   Table 3- Grouping of the 21 Studies for Review by Type of Interventions ................. 131   Table 4 - BF and Sociodemographic Characteristics by Night Feeding Group ........... 132   Table 5 – Comparison of Sleep Quantity & Quality by Time and Group .................... 133   Table 6 – Mother Sociodemographic, BF and Labor Characteristics by Group .......... 134   Table 7 – Infant Characteristics by Feeding Group ...................................................... 135

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List of Figures Figure 1 – Conceptual model of health behavior change (Sorensen et al. 2007/2003) 136   Figure 2 - Conceptual Model of a Moderator Effect .................................................... 137   Figure 3 - Conceptual Model of a Mediator Effect ...................................................... 138   Figure 4 - Hormonal Preparation of Breast for Lactation (Lawrence & Lawrence, 2005) ...................................................................................................................................... 139 Figure 5 - Conceptual Model of BF Maintenance ........................................................ 140   Figure 6 - Comparison of Nocturnal Sleep by Time and Night Feeding Group .......... 141   Figure 7 – Revised Conceptual Model of BF Maintenance ......................................... 142

Appendix A: Summary of Studies by Modifying Conditions ................................. 143

UCSF Library Release .............................................................................................. 150

1 CHAPTER ONE BF (BF) has been proven to be highly beneficial for the health and well-being of infants, mothers, families, and society at large. Among the prominent benefits for infants, breast milk protects against infection and illness (Coovadia et al., 2007; Heinig, 2001; Silverdal, Ekholm, & Bodin, 2007), decreases risk of obesity (Araujo, Victora, Hallal, & Gigante, 2006), reduces risk of childhood leukemia (Bener, Hoffmann, Afify, Rasul, & Tewfik, 2008), and optimizes cognitive development in infancy and childhood (Tanaka, Kon, Ohkawa, Yoshikawa, & Shimizu, 2008) as well as early adulthood (Mortensen, Michaelsen, Sanders, & Reinisch, 2002). For mothers, short-term benefits of BF include more rapid postpartum recovery (Labbok, 2001) and weight homeostasis (Jelliffe & Jelliffe, 1978). Associated with increased duration of lactation, long-term benefits for women include decreased risks for certain types of breast cancer (Collaborative Group on Hormonal Factors in Breast Cancer, 2002; Lord et al., 2008), and decreased risk for cardiovascular disease (Schwarz et al., 2009). BF is important to public health and the economy (Bonuck et al., 2002) since its duration for the first six months of life is commensurate with annual savings in the United States (US) of $3.6 billion in health care costs (Gartner et al., 2005). To achieve optimal benefits, it is recommended that all infants be exclusively breastfed in the first six months of life, with the gradual introduction of complementary food and continued BF thereafter for at least one year (American Academy of Pediatrics, 2005) or longer (WHO, 2001), as long as both mother and child desire. The original BF objectives of Healthy People 2010 (HP2010) were to increase the proportion of mothers who breastfeed their babies to 75% in the early postpartum period, 50% at 6 months, and

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25% at one year. However, BF behavior (exclusive or any BF) was not specified. Thus in 2007, HP2010 BF objectives were updated to specify exclusivity at 60% for infants born in the US through age 3 months and 25% through age 6 months [objectives 16-19d and 16-19e] (US Department of Health and Human Services, 2007). Currently, objectives for exclusive BF remain unmet with an exclusive BF rate of 30.5% at 3 months and 11.3% at 6 months postpartum among US infants born between 2005 and 2006 (CDC, 2008). BF initiation and duration is shown to be less prevalent in low-income and ethnically diverse populations (CDC, 2006; Celi, Rich-Edwards, Richardson, Kleinman, & Gillman, 2005). BF behaviors exhibited in these families include early introduction of breast milk substitutes such as infant formula and other solids and subsequent early weaning (Ertem, Votto, & Leventhal, 2001; Tender et al., 2009) with an overall low prevalence of exclusive BF (CDC, 2007; Tender et al., 2009). However, other than non- modifiable sociodemographic characteristics, the reasons why women from lower income and ethnically diverse backgrounds have lower rates of EBF are not well documented. I am interested in studying factors related to mother and infant that may affect BF outcome, especially exclusive BF, among low-income and ethnically diverse women. Lactation, the establishment and maintenance of a full milk supply, is considered the physiological completion of gestation (Lawrence & Lawrence, 2005). The completion of gestation includes not only healthy postpartum recovery for the mother but also healthy transition for her infant by BF or the provision of breast milk. BF has been viewed as an invaluable continuum for the transition of a fetus to a healthy human being (Bostock, 1962). BF is also a preventive health behavior (Dodgson, Duckett, Garwick, & Graham,

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2002) since the causes of certain health problems, particularly eating disorders, can be traced back to infancy and are usually related to early infant feeding. This dissertation research examined the following questions: 1) What happens in the first three months postpartum that may affect such a profound drop in BF rate for low-income women? 2) Why are certain undesirable BF behavior, such as early use of supplementation, exhibited more in women from lower income and ethnically diverse backgrounds than from women in higher income status? 3) What interventions have been tested and how effective are they in helping women to continue to breastfeed after the first three months of life? 4) When would be the most appropriate time to intervene to promote exclusive BF for low-income and ethnically diverse women?

Purpose The purpose of this dissertation is to add to current knowledge in human lactation about factors associated with the mother and infant affecting BF behavior, particularly when these dyads are predominantly low-income and ethnically diverse. The first chapter includes a description of various theoretical approaches used in human lactation studies and the role of theory, a conceptualization and definition of BF maintenance, and a critique of the Social Contextual Model by Sorensen and colleagues (2003). This chapter concludes with a description of a new conceptual model for BF maintenance. Based on this model, the second chapter presents a review of the literature on BF intervention categorized by factors (e.g., individual, interpersonal, and organizational) that

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influence BF behavior in low-income populations and will be submitted as a manuscript. The third chapter is a manuscript in review that describes maternal factors that affect BF behavior and compares these factors between mothers who exclusively breastfeed and mothers who use formula supplementation during the night. The fourth chapter is a manuscript describing infant factors that affect night-time infant feeding method and compares infants who receive exclusive breast milk to infants who get formula supplementation during the night. The fifth chapter provides a synthesis of findings, implications for nursing practice, and direction for future research.

Theoretical Approaches in Human Lactation Various theoretical frameworks have been used in human lactation studies to address different aspects of BF. Of the more abstract theories, the Freudian Theory of Body Ego has been used to study the metapsychological and neurophysiological aspects of BF (Lehtonen et al., 2006). Attachment Theory (Bowlby, 1969; Schore, 2005) has been used to study maternal responsiveness or maternal-infant bonding in full-term infants (Drake, Humenick, Amankwaa, Younger, & Roux, 2007; Pridham, Schroeder, Brown, & Clark, 2001), premature infants undergoing Kangaroo care (Tessier et al., 1998), and effects of early skin-to-skin care on BF behavior/outcome, and psychological adaptation in healthy mother-newborn dyads (Moore, Anderson, & Bergman, 2007). The Theory of Planned Behavior (Aizen, 2006; Ajzen, 1985) has been used to study young people’s attitudes toward BF (Giles et al., 2007), factors influencing BF initiation (DiGirolamo, Thompson, Martorell, Fein, & Grummer-Strawn, 2005; Khoury, Moazzem, Jarjoura, Carothers, & Hinton, 2005) and BF continuation (Carrere et al., 2005; Dodgson,

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Duckett, Garwick, & Graham, 2002; Dodgson, Henly, Duckett, & Tarrant, 2003; Rempel, 2004; Wambach, 1997). Social Cognitive Theory (Bandura, 1977) has been used to develop instruments to assess self-efficacy for BF during pregnancy (Noel-Weiss, Bassett, & Cragg, 2006) and postpartum (Creedy et al., 2003; Dai & Dennis, 2003). Theory of Reasoned Action (Ajzen & Fisbein, 1980) has been used to study nurses’ attitudes toward BF support (Bernaix, 2000). Organizational theories have been used in the establishment of BF accommodation in the work place (Beyer & Trice, 1978; Heinig, 2007; Huberman & Miles, 1984). Grounded theory approaches have been utilized in qualitative studies about BF and “becoming a mother” (Flacking, Ewald, Nyqvist, & Starrin, 2006), and pain associated with BF problem (Kvist, Larsson, & Hall-Lord, 2006). Psychoanalytic theory as well as phenomenology have been employed to explore the meaning of BF experience (Friedman, 1996; Locklin, 1995). Table 1 contains a summary of theories frequently used in human lactation research and the time frame for childbearing women. To examine BF maintenance, the conceptual model proposed by Sorensen et al. (2003) was selected for its ability to guide intervention research for health behavior change. Theory of Reasoned Action and Social Cognitive Theory (Ajzen & Fisbein, 1980; Bandura, 1977) are embedded in the model, but to better understand BF maintenance, an integration of a bio-cultural understanding of lactation within a socio-contextual approach to the mother-infant dyad is also required. BF maintenance depends on lactation establishment as much as social context of the dyad. Since human lactation is fundamentally a physiologic interaction or process, it is necessary to include physiologic

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theory in the model so that it could be adapted effectively to study BF maintenance. In the next section, the role and components of theory in the context of BF is presented.

The Role of Theory Meleis (2005) noted that “theory is the goal of all scientific work, theorizing is a central process in all scientific endeavors, and theoretical thinking is essential to all professional undertakings” (page 8). Theory helps to identify the focus, means, and goals of practice. Theory and conceptual models have been used synonymously since they both contain a set of interrelated concepts and propositions that are employed as guiding frameworks to describe, explain, and predict phenomena. Concepts and propositions are developed in the process of theorizing. Theoretical thinking involves identifying and defining phenomena important to the nursing discipline as well as society at large, evaluating theories or conceptual models to describe phenomena and guide research, and interpreting research findings in relationship to the selected theory. Based on these findings, suggestions to further refine, modify or extend theory are considered. Components of Theory Theories consist of assumptions, concepts, descriptions, propositions, and exemplars (Meleis, 2005). Assumptions are “statements that describe concepts or connect two concepts that are factual, accepted as truth, and represent values, belief, or goals” (Meleis, 2005, page 12). Assumptions connect aspects of knowledge that are usually derived from empirical evidence, observation, and experience. When assumptions are founded on philosophy, they may or may not represent the shared belief of the discipline (Meleis, 2005). For example, the assumption that BF is an invaluable continuum for the

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transition of a fetus to a healthy human being may not represent the shared belief of the nursing discipline for several reasons. The assumption may be based on philosophy and Aristotle’s inductive-deductive method (all mammals suckle their young, all humans are mammals therefore infants are suckled by their mothers), or an evolutionary approach (BF is the true completion of gestation). In addition, the term BF is not without controversy. Therefore, unless supported by empirical data, assumptions remain vulnerable to criticism. For instance, women who cannot breastfeed because of medical, psychological or psychiatric problems, and infants who suffer from rare medical conditions, may be part of the dyad for which mother’s milk is not advised. When assumptions are challenged, they become testable propositions. According to Meleis propositions are “the crux of a theory” where questions that guide exploration and research emerge (Meleis, 2005) (page 250). Considering the questions posed for this dissertation, the first question inquires about a phenomenon (i.e., a profound drop in rate of BF) as well as its temporality (i.e., period between first and sixth month), the second question inquires further by addressing specifically BF behaviors of low-income and ethnically diverse women compared to women with higher income, the third question follows with inquiry about what has been done to address the concerns in the first two questions, and the fourth question inquires about the most appropriate time for intervention. The next logical step would be to describe the phenomenon or concept from which operational definitions derive to determine what variables should be included and how they are best examined. Concept is a term that describes a particular phenomenon or a group of phenomena. A concept provides a more concise and efficient way of communicating an idea related to

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the phenomenon and facilitates further analysis and development of the phenomenon (Meleis, 2005). For example, the concept of “sleep deprivation” describes the phenomenon of what happens to people who are not getting enough sleep on a continual basis by detailing their sleep disturbances, changes in mood, and changes in behavior or interactions. For lactating mothers, sleep deprivation is also associated with a drop in prolactin secretion that may have an effect on milk production after birth (Bowen, 2003). Yet milk production, whether abundant or insufficient, does not guarantee that a mother will continue to breastfeed under all circumstances. Although it is receiving more attention on a national level (CDC, 2007), what exactly constitutes BF maintenance as a concept has not been clearly delineated in the literature. Conceptualization of BF Maintenance For centuries, and especially since the successful commercialization of artificial breast milk (i.e., infant formula), BF has been viewed with controversy (Lapham, 1987). The controversy has evolved into a conundrum, particularly in the speculation of BF as crucial for human species survival or simply a means of nutrient provision for infants. To address this conundrum, a careful examination of the concept “breast” and the concept “feed” for their definitions and meanings in society will be presented. Breast The word breast has many definitions. Breast is defined anatomically as “either of the pair of mammae occurring on the chest in humans and having a discrete areola around the nipple, … enlarged and softened by hormonally influenced mammary-gland development and fat deposition and which secrete milk after the birth of a child: the breasts of males normally remain rudimentary”(breast, n.d.). Breast can be both noun

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and verb. As a noun, breast is defined as “a source of nourishment” and “the center of affection and emotion.”

As a verb, breast is defined as an “encounter or advance against resolutely,” “confront boldly,” “contend with,” and “overcome or succeed against” (breast, n.d.; The American Heritage dictionary of the English language, 2006), page 228). Thus, based on these descriptions, breast connotes a food source, a center of affection, and a way of overcoming or succeeding against adversity. Feed The word feed is used as a verb or noun. As a verb, feed is defined as “to give food to,” “serve as food for,” “to provide the necessary material for development, maintenance, or operation,” “to gratify,” or simply “to eat” and “to be nourished or supported.” As a noun, feed is defined as “food,” “an allowance, portion, or supply of such food,” and “the act of eating” (feed, n.d.; The American Heritage dictionary of the English language, 2006), page 647). Therefore, feed means giving as well as receiving nourishment. Breastfeeding Based on the above definitions as well as current knowledge of human lactation, BF henceforth can be defined as: 1) A woman’s act of overcoming or succeeding against certain conditions to provide nourishment, which she produces from her breast or center of affection, for her infant’s growth and development; and 2) an infant’s act of being nourished and supported by receiving food coming from mother’s breast (breast, n.d.; feed, n.d.; Lawrence & Lawrence, 2005; The American Heritage dictionary of the English language, 2006), pp 228 & 647). As such, BF can be conceptualized as an interaction between mother and baby during which mother gives, and infant receives, food produced by the maternal body from her center of affection and emotion. The

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concept of giving and receiving within the dyad is important in BF, for one cannot be completed without the other. Therefore, in the context of BF, the mother-infant dyad should be operationalized as the unit of analysis. Breastfeeding Maintenance To maintain is defined as “to keep in existence or continuance,” “to support by aid, influence, protection.” (maintain, n.d.) From these definitions, maintaining BF is synonymous with supporting by aid, influence, and protection. As a concept, BF maintenance is comprised of three crucial components: 1) early BF success associated with physiological interaction between mother and infant, 2) BF support associated with social context, and 3) temporality or the time frame determined as crucial for BF continuation. The temporal aspect of BF maintenance will be discussed as part of lactation physiology. For the purpose of this dissertation research, the outcome of BF maintenance is dependent on exclusive BF behavior during the first three months. The following section includes description and evaluation of the selected conceptual model for its fit and potential to contribute to studying BF maintenance in low income and ethnically diverse populations. Evaluation of Social Contextual Model for BF Maintenance Sorensen and colleagues (2003) proposed a conceptual framework for addressing social contextual factors in health behavior interventions for working-class, multiethnic populations based on two assumptions: 1) Health behaviors are significant determinants of patterns of risk, and 2) Both patterns of health behaviors and patterns of risk differ by race/ethnicity and social class (Sorensen et al., 2003). BF maintenance can be considered a health behavior and thus this model holds potential to support this scientific inquiry.

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Paradigmatic Origin Sorensen et al. (2003) borrowed from the rich tradition of behavioral research and theories in creating this conceptual framework to address the social context of health behaviors (Sorensen et al., 2003). In predicting behavior change, the authors applied the individual psychosocial factors embedded in Cognitive Theory (Bandura, 1977), Theory of Reasoned Action (Ajzen & Fisbein, 1980), and Transtheoretical Model of Behavior Change (Prochaska & DiClemente, 1983). From these theories, concepts such as self- efficacy, attitudes and beliefs, and beliefs about the benefits and costs of behavior performance were extracted and employed in the model as individual factors which comprise the mediating variables. Self-efficacy, defined as a person’s confidence in his/her perceived ability to perform a specific task or behavior (Bandura, 1977), has been demonstrated to be a prominent influence on health behavior change (Dennis, 1999). Attitudes toward a behavior have been theoretically linked to intention to perform that behavior by a reasoned action approach that assumes behavior follows from beliefs, attitudes and intentions, and beliefs are a strong determinant of performing a specific behavior (Ajzen & Fisbein, 2005). In explicating the pathway by which income and race may influence health outcomes and risk-related behaviors, the authors used insight from social epidemiology (Sorensen et al., 2003). They used a social ecological framework from their previous research (Peterson et al., 2002) to conceptualize social contextual modifiers and mediators that cut across multiple levels of influence (Figure 1).

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Model Description The conceptual framework has been used by Sorensen and colleagues (Sorensen, Barbeau, Hunt, & Emmons, 2004; Sorensen et al., 2003; Sorensen et al., 2007) to guide the development of survey research and intervention research. Based on a social ecological model, this framework defines the overarching role of social context in behavior change that could be used to develop other interventions involving health behavior. In fact, interventions developed from the conceptual model have been utilized in research to address dietary and activity patterns of low-income postpartum women (Peterson et al., 2002) and to evaluate cancer prevention intervention aimed at increasing fruit and vegetable consumption of working-class multiethnic populations (Sorensen et al., 2007). The framework serves to illuminate the social contextual pathways by which race/ethnicity and social class may affect health behaviors (Sorensen et al., 2003). The diagram links sociodemographic characteristics, modifying conditions, mediating factors, health behaviors, and health outcomes. Sociodemographic Characteristics Sociodemographic characteristics are mainly social class, income, and race/ethnicity. Within the conceptual framework, social class is defined as “social relationship premised on people’s structural location within the economy” (Sorensen 2003, p. 189). Social class can exert control over a person’s outlook on life, access to educational and economic resources, and exposure to life stressors. Thus, social class can have a profound effect on health such that low-income populations exhibit not only increased health behavioral risks (e.g., smoking, obesity) but also less access to healthy

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food (e.g., fresh fruits and vegetables) and medical care (Sorensen et al., 2007; U.S. Department of Health and Human Services, 2000). Race and ethnicity are not only major determinants of social class, but have important implications for health outcomes (Sorensen et al., 2003). Race and ethnicity become a social contextual factor that shapes cultural norms, patterns of resource utilization, patterns of interpersonal interactions and expectations for individual behaviors. In turn, these patterns affect availability of social resources, culturally sensitive facilitators, and assets that can improve health outcomes (Sorensen et al., 2003). Modifying Conditions A moderator is an independent variable that affects the strength or direction of the relationship between a predictor variable and an outcome variable (Rose, Holmbeck, Coakley, & Franks, 2004). Also known as modifying factors, moderators are situated along the pathway between intervention and outcome. Modifying conditions comprise of modifying factors that independently impact an outcome, but are not likely to be influenced by intervention (Sorensen et al., 2007). Mediating Mechanisms Mediating mechanisms are defined as factors along the causal pathway between intervention and outcome (Sorensen et al., 2003). Mediating variables can be manipulated by intervention to affect outcome. Often a mediator variable is conceptualized as the mechanism through which one variable (predictor) influences another variable (outcome) (Rose, Holmbeck, Coakley, & Franks, 2004). In the model, mediating mechanisms are psychosocial factors conceptualized from behavioral theories and demonstrated by empirical evidence to influence intention to change behavior (Sorensen et al., 2003).

Full document contains 160 pages
Abstract: Breastfeeding (BF) is a health-promoting behavior and exclusive BF has proven economic and ecologic benefits to individuals and societies. Yet Healthy People 2010 BF objectives for exclusive BF remain unmet and prevalence is lowest for low-income populations. The purpose of this descriptive longitudinal study of 126 predominantly low income and ethnically diverse mother-infant dyads was to compare maternal and infant factors associated with nighttime BF behavior between exclusive BF dyads and supplemented dyads. Descriptive statistics, repeated measures ANOVA, independent t-tests, and Chi-square tests were used for analysis. BF behavior was categorized as either (1) exclusive BF , defined as 100% BF or breastmilk feeding on all three nights, or (2) supplementation , defined as any formula during any of the three nights. Compared to women in supplementation (n=59), women in exclusive BF (n=67) were older, more likely Caucasian, working at 36 weeks pregnant but not working at 1 month postpartum, in a relationship, and getting less help with baby at night. There was no group difference in objective sleep at the last month of pregnancy assessment. At one month postpartum, women in the supplementation group averaged 30 minutes less night sleep compared to women in the exclusive BF group. Compared to infants who were supplemented (n=54), infants who were exclusively breastfed (n=66) were significantly more likely to room-in with mothers in hospital and receive a home visit. They were statistically larger at birth, although the difference in size may not be clinically relevant. Assessment of sleep in new mothers is important for BF maintenance and more effort is needed to promote exclusive BF among younger women, African Americans and women of Asian descent. Rooming-in practice in the hospital after birth should be encouraged, as it was significantly associated with exclusive BF behavior at one month postpartum in this diverse sample of new families. Future research using a qualitative approach would be ideal to discover how nighttime feeding for new mothers evolves over time, their motivation for BF, and their network of influence in support of BF behavior. Findings from qualitative research will be useful in developing an effective intervention for BF maintenance.