Early life as a window to future respiratory health: rationale and design of the NELA birth cohort study

Abstract

Introduction: The Nutrition in Early Life and Asthma (NELA) study was designed to unravel the prenatal and the early postnatal life course factors that predict children’s respiratory health. We postulate that the interface between early life and future respiratory health involves offspring immune system alterations, microbiome adaptations, epigenetic mechanisms, and changes in the profile of volatile organic compounds (VOCs) in exhaled air. Methods: The ongoing NELA study, which started in March 2015, is a prospective population-based birth cohort set up in Spain enrolling pregnant women at 20 weeks of gestation. Several face-to-face questionnaires, tests and collections of biospecimens will be performed to 1000 mother-infant pairs at different time-points: 20, 24, and 32 weeks of gestation; birth; 3 and 18 months; and 4 and 7 years. Clinical outcomes comprise respiratory infections, atopic eczema, wheeze, newborn spirometry, multiple breath washout technique, and asthma. Assessments include fetal growth, maternal diet (including nutritional biomarkers) and adiposity, residential air pollution, endocrine disruptors, and infections (including microbial exposure). The exposures will be put in relation to the outcomes exploring several mechanisms, such as newborn Th1/Th2 unbalance, maternal and offspring microbiome adaptations, DNA methylation changes, and VOCs in exhaled breath. Results: Since March 2015, the study has recruited 160 women with a participation rate of 56%. At birth, 95% of the mother-child pairs initially recruited had been followed. At 3 months of age, 90% of the infants are still actively participating in the cohort. Conclusions: This prospective birth cohort consists of objective phenotyping, detailed exposure assessments, and biobanking. The cohort applies a system biology approach to unravel clinical and mechanistic insights of the early-life origins of respiratory diseases and to develop evidence-based prevention strategies.