To assess the association between duration of breastfeeding and infant infections, investigators from the Netherlands collected data from a population-based prospective cohort study of infants born in Rotterdam. Mothers of study children completed questionnaires at age 6 and 12 months regarding duration and exclusivity of breastfeeding and whether any infectious diseases occurred. Breastfeeding at different ages was categorized as exclusive or partial based on whether the infant received any formula or food in addition to breast milk prior to that time. Results were adjusted for important confounders such as maternal age, education, ethnicity, smoking, number of siblings, day care attendance, and family history of asthma and allergies. Infections were categorized as upper respiratory tract infection (URTI) for a serious cold, ear, or throat infection; lower respiratory tract infection (LRTI) for pneumonia, bronchitis or bronchiolitis; and gastrointestinal tract infection (GI).
Information on 4,164 infants was available. Compared to children who were never breastfed, in the first six months of life those who were breastfed exclusively until the age of 4 months and partially thereafter had a 35% lower risk of URTI, 50% lower risk of LRTI, and 59% lower risk of GI (all differences statistically significant). These children also had a 54% lower risk of LRTI between ages 7 and 12 months. Infants who were breastfed exclusively for six months also had significantly lower rates of URTI than those who were never breastfed. Overall, the length of exclusive breastfeeding was significantly associated with fewer URTI, LRTI, and GI in the first year of life. Partial breastfeeding, even for six months, did not significantly lower infection rates. Also, four months of exclusive breastfeeding without any later breastfeeding did not reduce rates of these infections.
The authors conclude that exclusive breastfeeding in developed countries should be recommended for at least four months, but preferably six months.
Previous studies have documented that breastfeeding results in improved infant and maternal health outcomes in both developed and developing countries.1–4 Although the World Health Organization has recommended that all children be exclusively breastfed for six months instead of four months, supporting studies have had methodological concerns such as varying duration and/or exclusivity of breastfeeding.5 Recent US breastfeeding initiation rates have approached the 2010 Healthy People Goals, but both duration of breastfeeding and exclusive breastfeeding fall short of the 2010 goals.6 The importance of duration and exclusivity are documented quite dramatically in the current study. Six months of partial breastfeeding or four months of exclusive breastfeeding without breastfeeding afterwards did not lower infection rates. However, significant reductions in rates of infection were obtained with exclusive breastfeeding for four months and partial thereafter. Exclusive breastfeeding for six months tended to be even more protective.
Several limitations of this study must be noted....