ELECTRONIC ARTICLE |
Reduced Risk of Neonatal Respiratory Infections Among Breastfed Girls but Not Boys
,
,||
* Channing Laboratory, Department of Medicine, Harvard Medical School and Brigham and Women’s Hospital, Boston, Massachusetts
Department of Ambulatory Care and Prevention, Harvard Medical School and Harvard Pilgrim Health Care, Boston, Massachusetts
HMO Research Network Center for Education and Research in Therapeutics, Boston, Massachusetts
|| Centers for Disease Control Eastern Massachusetts Prevention Epicenter, Boston, Massachusetts
Objective. 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.
Methods. 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 
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.
Results. 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).
Conclusions. 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.
Key Words: neonatal respiratory tract infections • breastfeeding, girls
Abbreviations: BWH, Brigham and Women’ • Hospital • HMO, health maintenance organization • HPHC, Harvard Pilgrim Health Care • HVMA, Harvard Vanguard Medical Associates • NNIS, National Nosocomial Infections Surveillance System • OR, odds ratio • CI, confidence interval
Received for publication Mar 14, 2003; Accepted May 22, 2003.
CiteULike 
Connotea 
Del.icio.us 
Digg 
Facebook 
Reddit 
Technorati 
Twitter What's this?
This article has been cited by other articles:
|
|
 |
|
  G. Nagel, G. Buchele, G. Weinmayr, B. Bjorksten, Y-Z. Chen, H. Wang, W. Nystad, Y. Saraclar, L. Braback, J. Batlles-Garrido, et al. Effect of breastfeeding on asthma, lung function and bronchial hyperreactivity in ISAAC Phase II Eur. Respir. J., May 1, 2009; 33(5): 993 - 1002. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 I U Ogbuanu, W Karmaus, S H Arshad, R J Kurukulaaratchy, and S Ewart Effect of breastfeeding duration on lung function at age 10 years: a prospective birth cohort study Thorax, January 1, 2009; 64(1): 62 - 66. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 K. Freeman, K. A. Bonuck, and M. Trombley Breastfeeding and Infant Illness in Low-Income, Minority Women: A Prospective Cohort Study of the Dose-Response Relationship J Hum Lact, February 1, 2008; 24(1): 14 - 22. [Abstract] [PDF]
|
|
|
|
 |
|
 T. W. Guilbert, D. A. Stern, W. J. Morgan, F. D. Martinez, and A. L. Wright Effect of Breastfeeding on Lung Function in Childhood and Modulation by Maternal Asthma and Atopy Am. J. Respir. Crit. Care Med., November 1, 2007; 176(9): 843 - 848. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. B. Wolf Is Breast Really Best? Risk and Total Motherhood in the National Breastfeeding Awareness Campaign Journal of Health Politics Policy and Law, August 1, 2007; 32(4): 595 - 636. [Abstract] [PDF]
|
|
|
|
 |
|
 K. A. Bonuck, K. Freeman, and M. Trombley Randomized controlled trial of a prenatal and postnatal lactation consultant intervention on infant health care use. Arch Pediatr Adolesc Med, September 1, 2006; 160(9): 953 - 960. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Recent References J Hum Lact, February 1, 2004; 20(1): 106 - 112. [PDF]
|
|
|
|
 |
|
 Minerva BMJ, October 11, 2003; 327(7419): 878 - 878. [Full Text] [PDF]
|
|
