Item No. 1 of 1

INVESTIGATOR: Rasmussen, K. M.

PERFORMING INSTITUTION:
NUTRITIONAL SCIENCES
CORNELL UNIVERSITY
ITHACA, NY 14853

WHY DO OBESE WOMEN BREASTFEED FOR LESS TIME THAN NORMAL-WEIGHT WOMEN

NON-TECHNICAL SUMMARY: More than half of American women of reproductive age are overweight and almost 30 percent are obese. Based on data collected in New York, we have shown that overweight and obese women breastfeed for less time than normal-weight women and are particularly likely to cease all breastfeeding soon after delivery and, thus, to fall short of national health recommendations for the duration of breastfeeding. These observations are important for the health of both mothers and their infants. Women who breastfeed only briefly retain more weight postpartum and miss the opportunity to take advantage of the other benefits of breastfeeding for their own later health. Infants who are breastfed only briefly are more likely to suffer from various illnesses and to become obese as children or adolescents than those who are breastfed for the recommended time. In the proposed research, we will use data on about 3000 pregnant women and their infants from the Infant Feeding Practices Study (IFPS) II, which was conducted recently by the Centers for Disease Control and the Food and Drug Administration. While pregnant, these women provided data about their motivations for breastfeeding. After the births of their babies, these women provided detailed information about how and why they fed their babies they way that they did. In the proposed research, we will use standard statistical techniques to test a series of hypotheses about how the psychosocial and sociocultural characteristics of women, the characteristics of their employment and their use of breast pumps might modify how obesity affects the duration of breastfeeding. The results of this research will be applicable both to the residents of New York and women living elsewhere in the United States. The long-term objective of this research is to learn more about why the duration of breastfeeding is shorter among obese than among normal-weight women. This is an essential step in developing ways to assist these women in meeting national recommendations for optimal breastfeeding.

OBJECTIVES: The long-term objective of this research is to develop a more comprehensive understanding of why the duration of breastfeeding is shorter among obese than among normal-weight women. This is an essential step in developing interventions to assist them in meeting national recommendations for optimal breastfeeding. More than half of American women of reproductive age are overweight and almost 30 percent are obese. Based on data collected in New York, we have shown that overweight and obese women breastfeed for less time than normal-weight women and are particularly likely to cease all breastfeeding soon after delivery and, thus, to fall short of national health recommendations for the duration of breastfeeding. These observations are important for the health of both mothers and their infants. Women who breastfeed only briefly retain more weight postpartum and miss the opportunity to take advantage of the other benefits of breastfeeding for their own later health. Infants who are breastfed only briefly are more likely to suffer from various illnesses and to become obese as children or adolescents than those who are breastfed for the recommended time. In the proposed research, we will use a newly released, nationally representative dataset that contains relevant information on about 3,000 women: the Infant Feeding Practices Study (IFPS) II, which was conducted by the Centers for Disease Control and the Food and Drug Administration. While pregnant, these women provided data about their motivations for breastfeeding. They also provided data nearly every month about their actual infant feeding practices and their reasons for adopting these practices. The results of the analyses proposed will be applicable both to the residents of New York and women living elsewhere in the United States. In the proposed research, we will determine whether (1)the psychosocial and sociocultural characteristics, knowledge about breastfeeding and intention to breastfeed of the respondents modify the association between obesity and duration of breastfeeding,(2) the duration of breastfeeding in minority women is as negatively affected by obesity as it is in white women (to the extent permitted by the racial/ethnic distribution of the participants in IFPS II),(3) postpartum factors, such as the experience with breastfeeding and pumping milk as well as the adequacy of maternity leave and workplace support for breastfeeding of the respondents, modify the association between obesity and duration of breastfeeding, and (4)characteristics of the infants of the respondents affect the duration of breastfeeding.

APPROACH: We will analyze data from about 3000 pregnant women and their infants in the IFPS II. They will be categorized by their pre-pregnant BMI and their racial/ethnic group. Many variables are available for control of possible confounding. Objective 1:To determine whether the psychosocial and sociocultural characteristics, knowledge about breastfeeding and intention to breastfeed of the respondents modify the association between obesity and duration of breastfeeding. Two hypotheses will be investigated: (a) the association between high pre-pregnant BMI and the duration of breastfeeding is modified by the psychosocial and sociocultural characteristics of the respondents and (b) the association between high pre-pregnant BMI and the duration of breastfeeding is mediated by the psychosocial and sociocultural characteristics of the respondents. We will use the same statistical approach used in our previous, more limited study on this issue. Objective 2:To determine whether the duration of breastfeeding in minority women is as negatively affected by obesity as it is in white women. The IFPS II study design included oversampling of minority women. Nonetheless, the proportion of minority respondents included was below that desired, so we may have to combine women into lighter and heavier categories of pre-pregnant BMI. We will use proportional hazards regression analysis to determine whether lighter women differ from heavier women in the duration of exclusive or any breastfeeding among black and Hispanic women. We will use logistic regression analysis to determine if these 2 groups within each minority population group differ in the whether they ever tried to breastfeed. Objective 3:To determine whether postpartum factors, such as experience with breastfeeding and pumping milk as well as the adequacy of maternity leave and workplace support for breastfeeding of the respondents, modify the association between obesity and duration of breastfeeding. Three hypotheses will be studied: (a) the association between high pre-pregnant BMI and the duration of breastfeeding is modified by characteristics of the employment of the respondents, (b) the association between high pre-pregnant BMI and the duration of breastfeeding is mediated by these characteristics, and (c) the use of breast pumps by respondents modifies the association between prepregnant BMI and the duration of breastfeeding. We will use the same statistical approach used in our prior study on the role of maternal psychosocial characteristics. Objective 4: To determine whether characteristics of the infants of the respondents affect the duration of breastfeeding. Infants will be characterized by the weight-for-gestational age compared to a reference. LGA infants will be compared to AGA and small-for gestational age babies. The pattern of exclusive and any breastfeeding in these 3 groups will be described with the use of unadjusted Kaplan-Meier survival analyses. Statistical differences among these 3 groups will be evaluated using proportional hazard analysis. These analyses will be stratified for maternal pre-pregnant BMI and normal-weight women delivering AGA infants will serve as the comparison group.

PROJECT CONTACT:

Name: Hoffmann, M. P.
Phone: 607-255-2224
Fax: 607-255-9499
Email: cuaes@cornell.edu