Written by: Sandeep Ravindran, Ph.D. | Issue # 102 | 2021
- Human milk consumption is known to provide several benefits for children, but it’s unclear if the mode of feeding makes a difference.
- A new study examines some of the long-term effects of feeding expressed milk versus breastfeeding on 6-year-old children.
- The study finds that feeding at the breast may offer clinically meaningful advantages to children’s working memory compared with feeding expressed milk.
- The researchers suggest that breastfeeding may offer some long-term advantages to children’s neurodevelopment compared with expressed milk feeding, although larger follow-up studies are required to clarify these results.
Could how you eat something matter as much as what you eat? At least when it comes to human milk, the answer is still unclear.
Human milk is known to provide several benefits to children. Studies have shown that exclusive breastfeeding and breastfeeding for a longer duration are associated with enhanced cognitive development of children, improved behavioral outcomes related to attention and hyperactivity, and benefits to food-related behaviors such as less food fussiness [1-9]. But researchers still don’t know whether feeding at the breast might confer some advantages over feeding expressed milk.
In the United States, more than 85% of infants fed human milk are fed expressed milk at least sometimes . “Pumping and feeding expressed milk has become extremely common over the past couple of decades in the U.S. and other countries, yet information about whether expressed milk is as beneficial for infants is lacking,” says Dr. Sarah Keim of the Ohio State University.
In a longitudinal study of U.S. mothers and children up to age 6, Keim and her colleagues examined associations between mode of feeding human milk and long-term effects on neurodevelopment and behavior . “We built a cohort of mothers and children with funding from the Ohio State University and the U.S. Centers for Disease Control and Prevention to learn more about the differences between expressed milk feeding and feeding at the breast,” says Keim. “The main challenge with a study like this is encouraging a high response rate among participants after many years,” she says.
The researchers were particularly interested in looking at the effects of breastfeeding versus feeding expressed milk on higher-level cognitive abilities that are predictive of school success, usually grouped under the umbrella-term “executive function” . They also examined long-term outcomes on global cognitive development and eating behaviors.
The researchers found that the mode of feeding human milk may be important to the development of executive function. Among 285 participants included in the analysis, feeding at the breast for longer periods of time was associated with clinically-meaningful advantages in working memory ability—a component of executive function—at 6 years of age. Each additional month of exclusive feeding at the breast decreased the risk of a working memory score compatible with an attention deficit hyperactivity disorder (ADHD) diagnosis by 22%.
However, the mode of human milk feeding did not show any association with global cognitive ability, and only weak associations were observed with eating behaviors. Feeding human milk was associated with increased food enjoyment, and longer exclusive feeding at the breast was associated with a small increase in emotional overeating and food fussiness.
The results suggest that the mode of feeding human milk may be important to the development of executive function. “Expressed milk feeding may not offer all the benefits of feeding at the breast for optimal neurodevelopment,” says Keim.
Executive function develops rapidly during the preschool years. The brain regions involved in executive function require several nutrients that are enriched in human milk, suggesting a potential mechanism by which milk intake could influence their development [1,2,6,13-16]. The researchers suggest that feeding at the breast may also offer infants greater maternal bonding opportunities compared with expressed milk feeding, which could play a role in development of early executive function [17,18].
The researchers note the need for follow-up studies to tease apart how the mode of feeding of human milk influences neurodevelopment. “Larger and more detailed studies are needed,” says Keim. These could include larger prospective studies that incorporate multiple complementary measures of child cognition, including objective laboratory assessments. “We are planning to follow up these results with future, more detailed studies,” says Keim.
The study concludes that feeding at the breast may offer advantages to some aspects of executive function, such as working memory, that expressed milk may not. “It’s difficult to shift clinical recommendations without stronger evidence, but other studies have started to show that expressed milk feeding may be less optimal than feeding at the breast for other child health outcomes as well,” says Keim. “It seems that if there is a choice available, feeding at the breast may be preferred over feeding expressed milk,” she says.
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