Sibship size, birth order and risk of asthma and allergy: protocol for a systematic review and meta-analysis.

ABSTRACT:

Introduction

The hygiene hypothesis suggests that reduced exposure to microbes might have contributed to the increase in prevalence and incidence of asthma and allergy observed during the second half of the last century. Following this proposal, several studies have investigated the role of sibship size and birth order in the development of asthma and allergic diseases, but the underlying evidence is conflicting. The objective of the present systematic review will be to identify, critically appraise and synthesise previous primary studies investigating the association of sibship size and birth order with the risk of asthma and allergic diseases.

Methods and analysis

The following databases will be searched: AMED, CABI, CINAHL, Embase, Google Scholar, OAIster, Open Access The

SUBMITTER: Lisik D 

PROVIDER: S-EPMC8383851 | biostudies-literature | 2021 Aug

REPOSITORIES: biostudies-literature