Infant formula preparation, handling, and related practices in the United States

To describe practices related to infant formula feeding: diluting and concentrating formula, mixing formula with warm tap water, sterilizing, storing prepared formula, heating in a microwave oven, putting the baby to bed with a bottle, and adding cereal and sweeteners to formula; to analyze characteristics related to compliance with recommended practices; and to examine the relation between formula handling and infant diarrhea.

Subjects were mothers who fed their infants formula (more than 1,000 subjects at each infant age). Data are from the US Food and Drug Administration's Infant Feeding Practices Study (IFPS), a national longitudinal survey with a nonprobability sample. Data were collected by mail, and formula practices were included at infant ages 2, 5, and 7 months.

Logistic regression was conducted and percentages and odds ratios were calculated, adjusting for instruction in preparing formula from a health care professional, education, income, age, parity, work status, and breast-feeding practices.

Failure to comply with recommendations was high for several practices with clear health implications; 33% of mothers mixed formula with warm tap water and up to 48% heated bottles in a microwave oven. Mothers of 2-month-old infants who received instruction from a health care professional and who breast-fed showed increased compliance, but few demographic characteristics, such as education, were related. Diarrhea increased with ambient holding of formula for older infants.

Advice from a health care professional can improve formula-handling behaviors. Dietitians and other health care professionals should provide information on proper preparation and handling of infant formula to all infant caregivers.