The rate of breastfeeding differs substantially by demographic, according to information from the Centers for Disease Control and Prevention. Because poorer women are least likely to nurse, Dr. Colen was interested in other factors that could play into negative health benefits normally blamed on formula feeding. She realized that previous studies may have suffered from selection bias: not considering factors such as race, age, family incomes, mother’s employment — all of which will affect breastfeeding as well as health outcomes. Mothers with higher incomes and more education remain the most likely to breastfeed.
Researchers analyzed a total of 8237 children made up of 7319 siblings and 1773 “discordant” sibling pairs, where one was breastfed and the other given the bottle. The study measured the children’s body mass index, obesity, asthma, hyperactivity, parental attachment, and behavior as well as academic achievement including vocabulary, reading, math, intelligence, and scholastic competence.
The breastfed children had better outcomes in body mass, hyperactivity, math, reading, vocabulary, scholastic competence and obesity, but when restricted to sibling pairs fed differently within the same family, scores on these indicators were balanced and not statistically significant: meaning that any differences could have occurred by chance. The researchers concluded that the siblings who were breastfed probably performed better because of other factors including socioeconomic status. Dr. Colen explains “For example, poorer kids have higher rates of obesity because their diets are worse.” The most surprising finding was that breastfed children had a greater risk for asthma.
Other research has found positive links between breastfeeding and good outcomes for children, Dr. Colen’s study simply suggests that children’s long-term health may have less to do with nursing than previously thought. “We need to look at other factors as well: adequate housing, type of parental employment, and a more detailed look at what happens that first year of life,” she said. She added that it’s a matter of being realistic about what breastfeeding can — and cannot — do.
