摘要：Objectives. We sought to determine the impact of sociodemographic and behavioral factors and state legislation on breastfeeding initiation (child ever fed breastmilk) and duration. Methods. We used data from a nationally representative study of children aged 6 to 71 months (N = 33 121); we calculated unadjusted and adjusted state estimates for breastfeeding initiation and duration. We used logistic regression models to examine factors associated with never breastfeeding or breastfeeding less than 6 months. We conducted a multilevel analysis of state legislation's role. Results. There were wide state variations in breastfeeding initiation and duration. The western and northwestern states had the highest rates. Covariate adjustment accounted for 25% to 30% of the disparity. Multivariate analysis showed that the adjusted odds of not being breastfed were 2.5- to 5.15-times greater in southern states compared with Oregon (reference). Children in states without breastfeeding legislation had higher odds of not being breastfed. Conclusions. Sociodemographic and maternal factors do not account for most breastfeeding rate variation. The association with breastfeeding legislation should be explored and may reflect cultural norms. Exclusive breastfeeding for 6 months—without supplementation from other sources such as water, glucose water, or formula—has been recommended by organizations such as the American Academy of Pediatrics, the American College of Obstetricians and Gynecologists, and the World Health Organization. 1 – 3 Numerous studies have indicated the benefits of increased duration and exclusivity of breastfeeding, including decreases in respiratory tract infections and decreases in gross motor, language, and developmental delays. 4 – 7 It is known that breastfeeding rates vary by demographic and socioeconomic factors and that these factors may impact differently on initiation, defined as whether the child was ever breastfed or fed breast milk, and duration. 8 Studies have indicated that characteristics such as increasing maternal age, education, and income, as well as non-Hispanic White race, being foreign born, and being a nonsmoker are associated with higher rates of breastfeeding. 9 – 13 Additionally, 2 sources of state-level data, the Ross Laboratories Mothers Survey and the National Immunization Survey, have indicated fairly wide variations in breastfeeding rates among states and regions. 10 , 14 , 15 However, neither survey has examined whether these state variations are diminished after multivariate adjustment, although Ryan et al. examined regional variations and found that after they adjusted for sociodemographic characteristics women in the western region of the United States were most likely to breastfeed in the hospital and for at least 6 months. 16 A multivariate examination of geographic variation is important for different reasons. Gaining further understanding of the large geographic variations in breastfeeding rates could lead to more effective interventions that might reduce the disparities. The best-performing states can serve as benchmarks for what can be achieved. The information for all states can help guide state health departments and policymakers in targeting resources and assessing the need for the development of breastfeeding promotion strategies. We sought to examine variations in breastfeeding initiation and duration across the 50 states and the District of Columbia (DC) and to determine the extent to which selected sociodemographic and behavioral factors account for such variation. We also examined the legislation on breastfeeding in each state and DC at the time of the study to determine its possible influence on breastfeeding practices.
