Sinha Anushua, Madden Jeanne, Ross-Degnan Dennis, Soumerai Stephen, Platt Richard
Channing Laboratory, Department of Medicine, Harvard Medical School and Brigham and Women's Hospital, Boston, Massachusetts 02115, USA.
Pediatrics. 2003 Oct;112(4):e303. doi: 10.1542/peds.112.4.e303.
The effect of breastfeeding on community-acquired neonatal infections has not been well studied, although the neonatal period is one of special vulnerability to infectious pathogens. Respiratory tract infections are the neonatal infection most commonly diagnosed after nursery discharge. We therefore chose respiratory tract infections diagnosed after nursery discharge as representative of neonatal community-acquired infection and studied the impact of breastfeeding on this neonatal infection syndrome.
An unmatched nested case-control study was performed within a previously defined study cohort of 13 224 mother-infant pairs delivering between October 1, 1990, and March 31, 1998. Infants who were delivered at < 37 weeks' gestation were excluded. Neonatal respiratory tract infections were defined using modified National Nosocomial Infections Surveillance System criteria and were included in the case series when diagnosed after nursery discharge and at age < or =30 days. Infant feeding status during the first month of life was ascertained using automated text search of electronic medical records and was categorized as exclusive breastfeeding, mixed feeding, or exclusive formula feeding.
A total of 241 neonatal respiratory tract infections were found, and 1205 control subjects were selected. Compared with control subjects, case infants were more often born during the winter respiratory syncytial virus season (48% vs 33%), more likely to have a sibling present (70% vs 54%), and more likely to be a member of a socioeconomically at-risk family (24% vs 18%). Case patients were less likely to be exclusively breastfed (38% vs 44%) and equally likely to be exposed to mixed feeding (35% vs 34%) relative to control subjects. When compared with formula feeding only, the odds ratio (OR) of exclusive breastfeeding was 0.70 (95% confidence interval [CI]: 0.49-0.99) and that of mixed feeding was 0.83 (95% CI: 0.58-1.2). However, when stratified by infant sex, the inverse association between breastfeeding and risk of neonatal respiratory tract infection was confined to neonatal girls, for whom the unadjusted ORs associated with breastfeeding only and mixed feeding were 0.5 (95% CI: 0.29-0.78) and 0.6 (95% CI: 0.35-0.93), respectively. There was no meaningful association between breastfeeding and risk of neonatal respiratory tract infection among neonatal boys, for whom the unadjusted ORs associated with breastfeeding only and mixed feeding were 1.1 (95% CI: 0.63-1.8) and 1.3 (95% CI: 0.74-2.1), respectively. After adjustment for year of birth, season of birth, siblings, and socioeconomic status, both exclusive breastfeeding and mixed feeding remained protective among girls, with ORs of 0.5 (0.29-0.78) and 0.6 (0.34-0.93), respectively. The corresponding ORs for boys were 1.1 (0.64-2.0) and 1.4 (0.78-2.4).
Breastfeeding was inversely associated with reduced risk of neonatal respiratory tract infections in girls but not in boys. Breastfeeding may confer protection against some community-acquired infections as early as the first month of life.
尽管新生儿期是对感染性病原体特别易感的时期之一，但母乳喂养对社区获得性新生儿感染的影响尚未得到充分研究。呼吸道感染是出院后最常诊断出的新生儿感染。因此，我们选择出院后诊断出的呼吸道感染作为新生儿社区获得性感染的代表，并研究母乳喂养对这种新生儿感染综合征的影响。
在先前定义的1990年10月1日至1998年3月31日期间分娩的13224对母婴队列中进行了一项非匹配巢式病例对照研究。排除孕周小于37周分娩的婴儿。新生儿呼吸道感染采用改良的国家医院感染监测系统标准进行定义，在出院后且年龄小于或等于30天时诊断的纳入病例系列。通过对电子病历的自动文本搜索确定出生后第一个月的婴儿喂养状况，并分为纯母乳喂养、混合喂养或纯配方奶喂养。
共发现241例新生儿呼吸道感染，并选择了1205名对照。与对照相比，病例婴儿更常在冬季呼吸道合胞病毒季节出生（48%对33%），更有可能有兄弟姐妹（70%对54%），更有可能是社会经济风险家庭的成员（24%对18%）。与对照相比，病例患者纯母乳喂养的可能性较小（38%对44%），接受混合喂养的可能性相同（35%对34%）。与仅配方奶喂养相比，纯母乳喂养的优势比（OR）为0.70（95%置信区间[CI]：0.49 - 0.99），混合喂养的优势比为0.83（95%CI：0.58 - 1.2）。然而，按婴儿性别分层时，母乳喂养与新生儿呼吸道感染风险之间的负相关仅限于新生儿女孩，纯母乳喂养和混合喂养的未调整OR分别为0.5（95%CI：0.29 - 0.78）和0.6（95%CI：0.35 - 0.93）。在新生儿男孩中，母乳喂养与新生儿呼吸道感染风险之间没有有意义的关联，纯母乳喂养和混合喂养的未调整OR分别为1.1（95%CI：0.63 - 1.8）和1.3（95%CI：0.74 - 2.1）。在对出生年份、出生季节、兄弟姐妹和社会经济地位进行调整后，纯母乳喂养和混合喂养在女孩中仍具有保护作用，OR分别为0.5（0.29 - 0.78）和0.6（0.34 - 0.93）。男孩的相应OR为1.1（0.64 - 2.0）和1.4（0.78 - 2.4）。
母乳喂养与女孩新生儿呼吸道感染风险降低呈负相关，但与男孩无关。母乳喂养可能早在出生后第一个月就对某些社区获得性感染具有保护作用。
