# The association between early-life respiratory infections and childhood asthma: a meta-analytic perspective

## TL;DR

Early-life viral infections and allergen exposure are strongly linked to childhood asthma and allergies, while nutritional and probiotic interventions show mixed results.

## Contribution

A meta-analysis identifying specific early-life factors that consistently influence asthma and allergic disease development in children.

## Key findings

- Early-life respiratory viral infections increase the risk of wheeze and asthma (OR = 1.59).
- Viral prophylaxis with maternal influenza vaccination reduces the risk of wheeze and asthma (OR = 0.78).
- Allergen and environmental exposures are linked to asthma and atopy (OR = 1.40 and 1.34 respectively).

## Abstract

Early-life exposures and interventions establish essential pathways which determine children’s development across respiratory, allergic, and growth pathways. The scientists conducted a systematic review and meta-analysis which combined multiple studies to examine how nutritional interventions and viral prophylaxis and probiotics and environmental exposures and allergen exposures and clinical factors in infants affect asthma and wheeze and atopy and growth outcomes.

The research team examined 51 studies which they categorized into eight different research areas. The researchers conducted random effects meta-analyses with inverse variance method to calculate pooled odds ratios (ORs) which included 95% confidence intervals (CIs). The researchers used I2 statistics to measure heterogeneity while they used funnel plots and Egger’s test to assess publication bias.

The nutritional interventions during pregnancy (OR = 0.89, 95% CI: 0.74–1.07, I2 = 68%) and early probiotics/microbiota modulation (OR = 1.10, 95% CI: 0.84–1.43, I2 = 96%) failed to show any significant results. The combination of viral prophylaxis with maternal influenza vaccination protected against wheeze and asthma and LRTI development (OR = 0.78, 95% CI: 0.72–0.85, I2 = 68%). The presence of early-life respiratory viral infections raised the likelihood of developing wheeze and asthma (OR = 1.59, 95% CI: 1.39–1.82, I2 = 90%) which accompanied allergen/atopy exposures (OR = 1.40, 95% CI: 1.30–1.50) and environmental exposures (OR = 1.34, 95% CI: 1.27–1.42) and infant clinical factors (OR = 1.29, 95% CI: 1.13–1.46, I2 = 82%). The long-term cohort studies established that early-life risk factors maintain a consistent impact on the development of asthma and allergic conditions (OR = 1.41, 95% CI: 1.35–1.48). The studies on viral prophylaxis and respiratory infections and allergen exposure demonstrated evidence of publication bias.

Research shows that early-life exposure to viral infections and allergens and environmental pollutants and infant clinical factors establishes strong links to the development of respiratory disorders and allergic diseases in children. The nutritional and probiotic treatments produced restricted and unstable results which demonstrate the requirement for specific preventive methods that should be implemented during early life.