Prolonged breastfeeding and protective effects against the development of allergic rhinitis: a systematic review and meta-analysis.

Background: There is insufficient evidence to confirm the protective effects of prolonged breastfeeding against the development of allergic rhinitis (AR).

Methodology: A systematic review and meta-analysis was performed to assess the associations between prolonged breastfeeding and AR symptoms later in life. Comparisons were conducted between breastfeeding durations less than 6 months and 6 months or more and between less than 12 months and 12 months or more. Exclusive breastfeeding and nonexclusive breastfeeding were analysed separately. Outcomes were risks of AR development later in life.

Results: Twenty-three observational studies (161,611 children, age 2-18 years, 51.50% male) were included. Two studies (9%) were with high quality. Both exclusive and nonexclusive prolonged breastfeeding (6 months or more) decreased the risk of AR. The long-term (12 months or more) nonexclusive breastfeeding lowered the likelihood of AR compared to the 12 months or fewer. The long-term exclusive breastfeeding did not show the same protective effect; however, this result was restricted to only one study.

Conclusions: Exclusive breastfeeding and nonexclusive breastfeeding for 6 months or more may have protective effects against the development of AR up to 18 years of age. The findings should be interpreted with caution given the limitation of low-quality observational studies.