"This is the first study that we are aware of to report an association between prolonged bottle-feeding and iron deficiency among a nationally representative sample of children one to three years of age. Our data suggest that prolonged bottle-feeding among Mexican-American infants may be at least partly responsible for the high prevalence of iron deficiency seen in this group," says Jane Brotanek, M.D., M.P.H., assistant professor of pediatrics at the Medical College. Dr. Brotanek practices at Children's Hospital of Wisconsin.
The study involved more than 2,100 children ages one to three years who took part in the National Health and Nutrition Examination Survey (1988-1994). Among these children, the prevalence of iron deficiency was six percent among whites, eight percent among blacks and 17 percent among Mexican Americans.
Researchers learned that the longer children were bottle-fed, the higher the prevalence of iron deficiency. That was especially true of Mexican American children, who were most likely to be bottle-fed for prolonged periods of time and had very high rates of iron deficiency. At 24 to 48 months of age, 36.8 percent of Mexican American children were still bottle-fed, compared with 16.9 percent of white and 13.8 percent of black children.
"Toddlers who are bottle-fed consume large volumes of non-iron-fortified milk. This results in gastrointestinal blood loss together with a displacement of iron-rich foods from the diet," according to Dr. Brotanek. She says the problem is important because iron-deficiency anemia in infancy and early childhood is associated with behavioral and cognitive delays. Iron deficiency and iron-deficiency anemia affect 2.4 million children in the world, with almost half a million children affected in the United States alone.
Dr. Brotanek points out that because of the harmful long-term effects of iron deficiency, its prevention in early childhood is an important public health issue. The study concluded that screening and nutritional counseling practices should be modified to address the increased risk of iron deficiency among children with prolonged bottle-feeding, especially among Mexican-American toddlers.
"Parents need to be aware that prolonged bottle-feeding and giving large volumes of milk to children older than 12 months can lead to problems with learning and development. Pediatricians need to counsel parents about feeding issues during the first year of life and encourage them to wean children from bottle-feeding by 15 months," Dr. Brotanek says.
The study was supported by the Center for the Advancement of Underserved Children at the Medical College of Wisconsin and the Children's Research Institute of Children's Hospital and Health System; the Department of Epidemiology, Health Policy Institute at the Medical College; and the Center for Child Health Research, Rochester, NY.
Coauthors of the study are Glenn Flores, MD, FAAP, associate professor of pediatrics, epidemiology, and health policy at the Medical College and Director of the Center for the Advancement of Underserved Children, and Peggy Auinger and Drs. Jill Halterman and Michael Weitzman from the University of Rochester School of Medicine and Dentistry. Dr. Weitzman is also with the American Academy of Pediatrics Center for Child Health Research, Rochester, NY.