MRC Epidemiology Resource Centre, University of Southampton, Southampton SO16 6YD, UK.
Matern Child Nutr. 2011 Jan;7(1):61-70. doi: 10.1111/j.1740-8709.2010.00241.x.
A number of studies in developed countries suggest that breastfeeding protects against infections in infancy. However, the choice to breastfeed is often related to maternal characteristics, and many of these studies are limited in the extent to which they can take account of confounding influences. In a prospective birth cohort study, we assessed the relationship between the duration of breastfeeding and the prevalence of lower respiratory tract infections, ear infections and gastrointestinal morbidity during the first year of life in 1764 infants. We considered the duration of all breastfeeding, including mixed feeding. Eighty-one per cent of the infants were breastfed initially, and 25% were breastfed up to 6 months. There were graded decreases in the prevalence of respiratory and gastrointestinal symptoms between birth and 6 months as breastfeeding duration increased; these were robust to adjustment for a number of confounding factors. The adjusted relative risks (95% confidence interval) for infants breastfed for six or more months compared with infants who were never breastfed were 0.72 (0.58-0.89), 0.43 (0.30-0.61) and 0.60 (0.39-0.92) for general respiratory morbidity, diarrhoea and vomiting, respectively. Duration of breastfeeding in the second half of infancy was less strongly related to diagnosed respiratory tract infections and gastrointestinal morbidity, although important benefits of breastfeeding were still seen. Our data provide strong support for a protective role of breastfeeding against respiratory and gastrointestinal infections in infancy. The graded inverse associations with breastfeeding duration suggest that current efforts to promote breastfeeding and increase duration will have important effects in reducing morbidity in infancy.
一些发达国家的研究表明，母乳喂养可预防婴儿期感染。然而，母乳喂养的选择通常与产妇的特征有关，而且许多此类研究在多大程度上能够考虑混杂因素的影响是有限的。在一项前瞻性出生队列研究中，我们评估了 1764 名婴儿在生命的第一年中母乳喂养持续时间与下呼吸道感染、耳部感染和胃肠道发病率之间的关系。我们考虑了所有母乳喂养的持续时间，包括混合喂养。最初有 81%的婴儿母乳喂养，25%的婴儿母乳喂养至 6 个月。随着母乳喂养时间的增加，出生至 6 个月期间呼吸道和胃肠道症状的患病率逐渐下降；这些结果在调整了许多混杂因素后仍然稳健。与从未母乳喂养的婴儿相比，母乳喂养 6 个月或以上的婴儿的调整相对风险（95%置信区间）分别为 0.72（0.58-0.89）、0.43（0.30-0.61）和 0.60（0.39-0.92），分别用于普通呼吸道疾病、腹泻和呕吐。婴儿在婴儿期后半期母乳喂养的持续时间与诊断出的呼吸道感染和胃肠道发病率的相关性较弱，但仍能看到母乳喂养的重要益处。我们的数据为母乳喂养对婴儿期呼吸道和胃肠道感染的保护作用提供了有力支持。母乳喂养持续时间呈梯度反比关系，这表明目前促进母乳喂养和增加母乳喂养持续时间的努力将对降低婴儿期发病率产生重要影响。
