PREVENT 1 is a nationwide prospective Swedish infant cohort established to characterise gut microbiome development during the first 2 years of life and relate microbial trajectories to feeding, infections, growth and everyday well-being, successfully recruiting 253 infants with high retention through three phases of data collection completed in December 2024.
PREVENT 1 successfully enrolled 253 infants nationwide in Sweden from September 2023 through targeted digital channels.
The cohort demonstrated high retention across all three data collection phases.
At enrolment, 42.3% of infants were older than 7 months of age.
At enrolment, 73.9% of infants had weight-for-length z-scores in the normal range.
Exclusive breastfeeding at 4 months was reported for 58.9% of enrolled infants.
The study design integrates repeated infant stool sampling with shotgun metagenomics analysis alongside aligned parental questionnaires, stool photographs, and infant cry recordings.
Future analyses are planned to examine microbiome features, resistome profiles and functional pathways in relation to antibiotic exposure, feeding, growth and infant health outcomes.
This research describes the setup and baseline characteristics of PREVENT 1, a large Swedish study tracking how bacteria in babies' guts develop during the first two years of life. Researchers recruited 253 babies from across Sweden and collected poop samples along with detailed questionnaires from parents at three time points spaced roughly three months apart. The study also gathered stool photographs and recordings of babies crying. Analysis of the poop samples uses advanced DNA sequencing to identify all the microorganisms present, not just specific ones. Nearly all families who enrolled stayed in the study through all three collection phases, which is considered very high retention for this type of research. At the start of the study, the researchers recorded that about 59% of babies had been exclusively breastfed up to 4 months of age, and about 74% had normal weight-for-length measurements. Parents answered detailed questions about pregnancy, birth, feeding, infections, gut symptoms, and general well-being. These baseline characteristics help describe who is in the study and will allow future researchers to account for differences between families when analyzing results. This research matters because the community of microorganisms living in a baby's gut during early life may have lasting effects on health, including risk of infections, growth, and well-being. By following a large group of babies over time and combining microbiome data with detailed health information, this cohort will help scientists understand how factors like breastfeeding, antibiotic use, and diet shape the gut microbiome — and how those microbial patterns connect to health outcomes. The researchers also plan to link study data to Swedish national health registers and to analyze antibiotic resistance genes found in the babies' gut bacteria, which could have broader public health relevance.
Orwa S, Vlajic M, Cavani E, Devall A, Hugerth L, Brusselaers N, et al.. (2026). PREVENT 1, a nationwide Swedish infant cohort for longitudinal gut microbiome profiling and early-life health outcomes: cohort profile.. BMJ open. https://doi.org/10.1136/bmjopen-2026-118233