Prospective Cohort Study of Breastfeeding and the Risk of Childhood Asthma

Anne Kristine Lossius, Maria Christine Magnus, Jon Lunde, Ketil Størdal*

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

7 Citations (Scopus)
252 Downloads (Pure)


Objectives To study whether the duration of breastfeeding and time for introduction of complementary foods was associated with the risk of childhood asthma. Study design We used data from the Norwegian Mother and Child Study, a nationwide prospective cohort study that recruited pregnant women from across Norway between 1999 and 2008. Children with complete data of breastfeeding up to 18 months and current age >7 years were eligible (n = 41 020). Asthma as the primary outcome was defined based on ≥2 dispensed asthma medications at age 7 years registered in the Norwegian Prescription Database. We used log-binomial regression models to obtain crude relative risks (RRs) in the main analysis, and adjusted for selected confounders in multivariable analyses. Results For duration of any breastfeeding, 5.9% of infants breastfed <6 months (adjusted RR [aRR] 1.05, 0.93-1.19) and 4.6% breastfed 6-11 months (aRR 0.96, 0.87-1.07) had dispensed asthma medications at age 7 years compared with 4.6% of infants breastfed ≥12 months (Ptrend .62). Infants still breastfed at 6 months, but introduced to complementary foods <4 months and 4-6 months, had an aRR of 1.15 (0.98-1.36) and 1.09 (0.94-1.27) respectively, compared with infants fully breastfed for 6 months (Ptrend .09). Ages at introduction of solids or formula separately were not significant predictors (Ptrend .16 and .08, respectively). Conclusions We found no association between duration of breastfeeding or age of introduction to complementary foods and asthma at age 7 years.
Original languageEnglish
Pages (from-to)182-189.e2
Number of pages10
JournalJournal of Pediatrics
Early online date1 Feb 2018
Publication statusPublished - 1 Apr 2018


  • complementary feeding
  • allergy
  • protection
  • atopy

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