The gut microbiota is central to human health, but its establishment in early life has not been quantitatively and functionally examined. Applying metagenomic analysis on fecal samples from a large cohort of Swedish infants and their mothers, we characterized the gut microbiome during the first year of life and assessed the impact of mode of delivery and feeding on its establishment. In contrast to vaginally delivered infants, the gut microbiota of infants delivered by C-section showed significantly less resemblance to their mothers. Nutrition had a major impact on early microbiota composition and function, with cessation of breast-feeding, rather than introduction of solid food, being required for maturation into an adult-like microbiota. Microbiota composition and ecological network had distinctive features at each sampled stage, in accordance with functional maturation of the microbiome. Our findings establish a framework for understanding the interplay between the gut microbiome and the human body in early life.

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Using large cohorts of well-characterized subjects from different centers allowed construction of robust reference ranges for a new automated IGF-I assay. The strict adherence to recent consensus criteria for IGF-I assays might facilitate clinical application of the results.

Highlights d Children gut microbiota mature along similar trajectories but at different speeds d Different microbes follow discrete trajectories in the developing gut microbiota d The effect of c-section on gut microbiota is normalized in 3-5year-old children d The gut microbiota has not yet reached adult complexity in 5years-old children

We present an extensive set of assay-specific age- and sex-adjusted normative data for concentrations of IGFBP-3 and the molar IGF-I to IGFBP-3 ratio and demonstrate distinct sex specific differences across the life span.

Many mothers reported breastfeeding problems that are associated with an early cessation. This is preventable with support, but the timing is crucial. To promote breastfeeding, the support from the child health centres must be tailored with the maternal perspective in mind.

The new reference values for waist circumference and waist-to-height ratio for Swedish preschool children enable future identification of new risk populations for childhood obesity. For clinicians, new reference charts for these two variables are provided for practical use.

Purpose To study the relationship between the tooth-brushing habits during the preschool ages and caries prevalence at the age of 5 years and to investigate a possible association with the mode of delivery. Methods The study population consisted of 336 children that were orally examined at 2, 3 and 5 years. All stages of caries were scored on tooth and surface level. Data on tooth brushing behaviour were collected through semi-structured interviews. Results At 5 years, the attrition rate was 13.1%. The total caries prevalence (cavitated and non-cavitated lesions) was 18.9%. The vast majority of the parents assisted their child with the brushing and 98% used fluoride toothpaste. The relative risk (RR) for caries was significantly (p < 0.05) increased for "tooth brushing less than twice daily" at two (RR 2.1, 95% CI 1.3-3.3, p < 0.01) and 3 years (RR 3.6, 95% CI 2.0-6.7; p < 0.001). Likewise, reporting "major/minor difficulties to perform tooth brushing" at 2 and 3 years was significantly related to caries development at the age of five (RR 1.5, 95% CI 1.0-2.4, p < 0.05 and RR 2.5, 95% CI 1.4-4.3; p < 0.01). We found no significant association between the tooth brushing habits and the mode of delivery. Conclusions Less than twice daily tooth-brushing and difficulties to perform the procedure during the first preschool years were significant determinants of caries prevalence at the age of 5 years. Health professionals should, therefore, give special attention and assist parents to improve and optimize their tooth brushing behaviour during the preschool years.