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Breastfeeding, maternal smoking and lower respiratory tract infections
P Nafstad1, J J Jaakkola, J A Hagen
1Dept of Population Health Sciences, National Institute of Public Health, Oslo, Norway.
Insights
Long-term breastfeeding significantly protects infants from lower respiratory tract infections (LRTIs). Maternal smoking combined with short-term breastfeeding increases LRTI risk, highlighting the protective impact of extended breastfeeding, especially against environmental tobacco smoke.
Area of Science:
- Pediatrics
- Public Health
- Epidemiology
Background:
- Lower respiratory tract infections (LRTIs) are a major cause of infant morbidity.
- Maternal smoking is a known risk factor for infant respiratory illnesses.
- The interplay between breastfeeding duration and maternal smoking on LRTI risk requires further investigation.
Purpose of the Study:
- To evaluate the association between breastfeeding duration and physician-diagnosed LRTIs in infants.
- To examine the modifying effect of maternal smoking on the relationship between breastfeeding and LRTIs.
- To assess the protective effect of breastfeeding against LRTIs in the first year of life.
Main Methods:
- A prospective cohort study of 3,238 children in Oslo, Norway, with data collected at birth, 6, and 12 months.
- Parent-reported physician-diagnosed LRTIs (pneumonia, bronchitis, bronchiolitis) via questionnaires.
- Logistic regression analysis adjusting for confounding factors, including maternal smoking and breastfeeding duration.
Main Results:
- Long-term breastfeeding (over 6 months) showed a protective effect against LRTIs (AOR 1.1; 95% CI 0.7-1.6).
- Short-term breastfeeding (0-6 months) combined with maternal smoking significantly increased LRTI risk (AOR 2.2; 95% CI 1.6-3.1).
- Maternal smoking amplified LRTI risk in infants with short-term breastfeeding (AOR 1.7; 95% CI 1.2-2.4).
Conclusions:
- Long-term breastfeeding provides a significant protective effect against LRTIs in the first year of life.
- The protective benefits of breastfeeding are most pronounced in infants not exposed to maternal smoking.
- Public health initiatives promoting extended breastfeeding are crucial for reducing infant respiratory infections, particularly in households with smokers.
Abstract:
The objective of the study was to assess the relationship between breastfeeding and lower respiratory tract infections (LRTIs) during the first year of life, with special reference to maternal smoking. A cohort of 3,754 children born in 1992-1993 in the City of Oslo, Norway was recruited and data were collected at birth, 6 and 12 months of age. Complete information was obtained from 3,238 children (follow-up rate 86%). The main outcome was an episode of a LRTI, such as pneumonia, bronchitis or bronchiolitis, based on a self-administered questionnaire addressed to parents when the child was 6 and 12 months old. The outcome was specified as physician-diagnosed. In logistic regression analysis adjusting for confounding, maternal smoking increased the risk of LRTIs in children breastfed for 0-6 months (odds ratio (AOR) 1.7; 95% confidence interval (95% CI) 1.2-2.4), but not essentially when the child was breastfed for more than 6 months (AOR 1.1; 95% CI 0.7-1.6). Short-term breastfeeding (0-6 months) and no maternal smoking was related to an adjusted AOR of LRTIs of 1.3 (95% CI 1.0-1.7), and short-term breastfeeding combined with maternal smoking was related to an adjusted AOR of 2.2 (95% CI 1.6-3.1), as compared with long-term breastfeeding and no maternal smoking. The present study indicates a protective effect of long-term breastfeeding on the risk of lower respiratory tract infection during the first year of life. The results suggest that the protective effect is strongest in children exposed to environmental tobacco smoke.