Antibiotics-use in utero and early-life and risk of chronic childhood conditions in New Zealand: a methods protocol using linked data

Abstract Background The incidence of many common chronic childhood conditions has increased globally in the past few decades. A potential role for antibiotic-(over)-use has been suggested with dysbiosis of the gut microbiome hypothesised to play a key role. This linkage study aims to assess the role of antibiotic-use in utero and in early-life in the development of Type 1 Diabetes (T1D), Attention Deficit Hyperactive Disorder (ADHD) and Inflammatory Bowel Disease (IBD). Methods The study design involves several retrospective cohort studies using linked administrative health and social data from Statistics New Zealand’s Integrated Data Infrastructure. It uses data for all children, and their mothers, born in New Zealand between October 2005 and December 2010 (n = 334,204). Children’s antibiotics-use are identified for four time periods (pregnancy, ≤ 1 year, ≤ 2 years, and ≤ 5 years) and the development of T1D, ADHD, and IBD is measured from the end of the antibiotics-use periods until death, emigration, or the end of the follow-up period (2021), whichever came first. Children who emigrated or died before the end of the antibiotics-use period are excluded. Cox proportional hazards regression models are used whilst adjusting for a range of potential confounders. Discussion These studies, using detailed, complete, and systematically collected antibiotic prescription data, will provide critical new knowledge regarding the role of antibiotics in the development of common chronic childhood conditions. Thus, it has the potential to contribute to the development of primary prevention strategies, through, for example, targeted changes in antibiotic-use.