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Background Human milk contains a diverse community of bacteria believed to play a role in breast health and inoculation of the infant's gastrointestinal tract. The role of maternal nutrition and infant feeding practices on the human milk microbiota remains poorly understood. Objective Our aim was to explore the associations between maternal diet (delivery to 3 mo postpartum), infant feeding practices, and the microbial composition and predicted function in milk from women with varied metabolic status. Methods This was an exploratory analysis of a previously completed prospective cohort study of women with varying degrees of gestational glucose intolerance (NCT01405547). Milk samples (n = 93 mothers) were collected at 3 mo postpartum. Maternal dietary information (validated food-frequency questionnaire) and infant feeding practices (human milk exclusivity, frequency of direct breastfeeding per day) were collected. V4-16S ribosomal RNA gene sequencing (Illumina MiSeq) was conducted to determine microbiota composition. Results Intake of polyunsaturated fat [β estimate (SE): 0.036 (0.018), P = 0.047] and fiber from grains [0.027 (0.013), P = 0.048] were positively associated with ɑ-diversity (Shannon index) of human milk. Overall microbial composition of human milk clustered based on human milk exclusivity (weighted UniFrac R2 = 0.034, P = 0.015; Bray-Curtis R2 = 0.041, P = 0.007), frequency of direct breastfeeding per day (Bray-Curtis R2 = 0.057, P = 0.026), and maternal fiber intake from grains (Bray-Curtis R2 = 0.055, P = 0.040). Total fiber, fiber from grains, dietary fat, and infant feeding practices were also associated with a number of differentially abundant taxa. The overall composition of predicted microbial functions was associated with total fiber consumption (Bray-Curtis R2 = 0.067, P = 0.036) and human milk exclusivity (Bray-Curtis R2 = 0.041, P = 0.013). Conclusions Maternal consumption of fiber and fat, as well as mother's infant feeding practices, are important determinants of the human milk microbiota. Understanding whether these microbial changes impact an infant's overall health and development requires future study.

Background Data on how baseline characteristics, acuity, morbidity, and nutrition work in combination to affect the growth of very-low-birth-weight (VLBW, <1500 g) infants are limited. Objective We aimed to determine factors associated with in-hospital weight, length, and head circumference (HC) trajectories of VLBW infants. Methods VLBW infants (n = 316) from the GTA-DoMINO trial were included. Linear mixed-effects models assessed relations of baseline characteristics, acuity (at birth, across hospitalization), major morbidities, and nutrition (enteral feeding type, macronutrient/energy intakes) with changes in anthropometrics over hospitalization (days 1–8, 9–29, 30–75). Results Specific factors and the strength of their associations with growth depended on in-hospital time interval. Small-for-gestational-age infants experienced weight gain (4.3   g · kg−1 · d−1; 95% CI: 2.0, 6.5   g · kg−1 · d−1) during days 1–8, versus weight loss (−4.6     g · kg−1 · d−1; 95% CI: −5.6, −3.7     g · kg−1 · d−1) among appropriate-for-gestational-age infants (P < 0.001). Positive-pressure ventilation (versus oxygen/room air) was associated with slower weight (−1.8    g · kg−1 · d−1) and HC (−0.25 cm/wk) gain during days 9–29 (P < 0.001). Morbidities were negatively associated with growth after days 1–8, with patent ductus arteriosus (PDA) showing negative associations with weight (−2.7     g · kg−1 · d−1), length (−0.11 cm/wk), and HC (−0.21 cm/wk) gain during days 9–29 (P < 0.001). Macronutrient/energy intakes were associated with weight across hospitalization (P ≤ 0.01), with greater weight gain (1.3–3.0 g  ·  kg−1  ·  d−1) among infants achieving macronutrient/energy recommendations during days 9–29 and 30–75. Macronutrient/energy intakes were associated with HC during the first month (P = 0.013–0.003), with greater HC gain (0.07–0.12 cm/wk) among infants achieving protein, lipid, and energy recommendations during days 9–29. Conclusions Baseline characteristics, acuity, morbidity, and nutrition factors were independently associated with VLBW infant growth. A focus on achieving macronutrient/energy recommendations and improving nutrient delivery to PDA-diagnosed infants may yield improvements to their growth. This trial was registered at www.isrctn.com as ISRCTN35317141.