Abstract
Establishment of low birth weight (LBW) infant gut microbiota may have lifelong implications for the health of individuals. However, no longitudinal cohort studies have been conducted to characterize the gut microbial profiles of LBW infants and their influencing factors. Our objective was to understand how the gut bacterial community structure of LBW and normal birth weight (NBW) infants varies across the first 3 months of life and assess the influencing factors. In this observational cohort study, gut bacterial composition was identified with sequencing of the 16S rRNA gene in fecal samples of 69 LBW infants and 65 NBW controls at 0 day, 3 days, 2 weeks, 6 weeks, and 3 months (defined as stages 1–5) after birth. Alpha-diversity of both groups displayed a decreasing trend followed by slight variations. There were significant differences on the Shannon index of the two groups at stages 1 to 3 (P = 0.041, P = 0.032, and P = 0.014, respectively). The microbiota community structure of LBW infants were significantly different from NBW infants throughout the 3 months (all P < 0.05) but not at stage 2 (P = 0.054). There was a significant increase in abundance in Firmicutes while a decrease in Proteobacteria, and at genus level the abundance of Enterococcus, Klebsiella, and Streptococcus increased while it decreased for Haemophilus in LBW group. Birth weight was the main factor explaining the observed variation at all stages, except at stage 2. Delivery mode (4.78%) and antibiotic usage (3.50%) contributed to explain the observed variation at stage 3, and pregestational BMI (4.61%) partially explained the observed variation at stage 4. In conclusion, gut microbial communities differed in NBW and LBW infants from birth to 3 months of life, and were affected by birth weight, delivery mode, antibiotic treatment, and pregestational BMI.
Highlights
Low birth weight, defined as less than 2,500 × g, is a common but serious event, despite improvements in healthcare (Franz et al, 2018)
Sixty-nine low birth weight (LBW) infants and 65 normal birth weight (NBW) infants were enrolled in this prospective observational cohort study and the inclusion criteria were as follows: All the pregnant women were admitted to the Beijing Obstetrics and Gynecology Hospital before delivery, the LBW infants were immediately hospitalized in the Neonatal Intensive Care Unit (NICU) of the Beijing Obstetrics and Gynecology Hospital after delivery, and the NBW infants were immediately placed in the newborn nursery with their mother after delivery
Mothers of LBW infants did not differ in age or pregestational body mass index (BMI) from mothers of NBW infants but they were more likely to be diagnosed with gestational diabetes mellitus (GDM) and gestational hypertension
Summary
Low birth weight, defined as less than 2,500 × g, is a common but serious event, despite improvements in healthcare (Franz et al, 2018). The importance of gut microbiota in the LBW infants is clearly evident in considering the risks of developing late-onset sepsis (Keunen et al, 2015) and necrotizing enterocolitis (NEC) (O’Connor et al, 2016). The gut microbiota of infants undergoes rapid dynamic changes in the first few months to years of life and these changes are hypothesized to affect their health (Madan et al, 2012; Carlson et al, 2018). LBW infants have distinct gut microbiota with lower diversity and greater abundance of potential pathogens (Brooks et al, 2018) such as Enterococcus spp., Staphylococcus aureus, Klebsiella spp., Acinetobacter spp., Pseudomonas aeruginosa, and Enterobacteriaceae, which are the most frequent cause of nosocomial infections (Hu et al, 2015). Such research is important as the ethnic origin of individuals may be a key factor to consider in microbiota research (Deschasaux et al, 2018)
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