Maternal birthplace and breastfeeding initiation among term and preterm infants: a statewide assessment for...

Among premature infants, formula feeding increases the risk for necrotizing enterocolitis, delayed brainstem maturation, decreased scoring on cognitive and developmental tests, and delayed visual development. With this in mind, many interventions are designed to increase breast milk consumption in preterm infants. Breastfeeding initiation rates among US premature infants are not collected nationally, however, and published data on breastfeeding rates in this population are limited. In addition, national surveys calculate breastfeeding rates among term infants according to maternal race/ethnicity, but maternal birthplace is not recorded. This is likely to be important, because breastfeeding is the cultural norm in the countries of origin for many non-US-born US residents. Massachusetts has a diverse racial/ethnic population, including many non-US-born women. The goals of this study were to compare breastfeeding initiation rates among preterm and term infants in Massachusetts in 2002 and to determine the effect of maternal race/ethnicity and birthplace on breastfeeding initiation rates among term and preterm infants.

Massachusetts Community Health Information Profile, an online public health database that was created by the Massachusetts Department of Public Health, includes breastfeeding initiation data that are obtained from the electronic birth certificate, which we used to compare breastfeeding rates among preterm and term infants. Birth-linked demographics and data that also were accessed were maternal age, race/ethnicity, birthplace, and health insurance (public or private) as an indicator of socioeconomic status and infant's gestational age. We assessed the association between breastfeeding initiation and maternal birthplace, as well as race/ethnicity and the other potential confounders, using logistic regression.

There were 80,624 births in Massachusetts in 2002, and 8.2% (6611) of newborns had a gestational age <37 weeks. The state's overall breastfeeding initiation rate was 74.6%. We excluded records of mothers who were younger than 15 years and older than 39 years, nonsingleton births, infants with a gestational age <24 weeks and >42 weeks, and records with missing data. Of the total births in Massachusetts, 67,884 (84%) met inclusion criteria for this study. Breastfeeding initiation rates were lowest among preterm infants of the youngest gestational ages. Breastfeeding initiation was 76.8% among term infants born at 37 to 42 weeks, 70.1% among infants born at 32 to 36 weeks, and 62.9% among infants born at 24 to 31 weeks. In univariate analysis, among preterm infants, a lower proportion of US-born black, Asian, and Hispanic mothers initiated breastfeeding than US-born white mothers; non-US-born black and non-US-born Hispanic mothers had the highest breastfeeding initiation rates. Among term infants, US-born black mothers had the lowest initiation rates, and non-US-born black and non-US-born Hispanic mothers had the highest. In multivariate logistic regression, however, after controlling for mother's age, race, birthplace, and insurance, US-born white mothers were least likely to breastfeed either term or preterm infants when compared with any other racial/ethnic group, including US-born black mothers. The likelihood that non-US-born Hispanic mothers would breastfeed was almost 8 times greater than that for US-born white mothers for a preterm infant and almost 10 times greater for a term infant. In multivariate logistic regression analysis stratified by gestational age for both preterm and term infants, older mothers and mothers with private health insurance were most likely to breastfeed.

In Massachusetts, preterm infants were less likely to receive breast milk than term infants, and the likelihood of receiving breast milk was lowest among the youngest preterm infants. In multivariate logistic regression, mothers who were born outside the United States were more likely than US-born mothers to breastfeed either term or preterm infants in all racial and ethnic groups. In an unexpected finding, US-born white mothers were less likely to breastfeed term or preterm infants than US-born black mothers or mothers of any other racial or ethnic group.