Michelle R. Asbury

Understanding how human milk composition, particularly the milk microbiota, shapes infant gut microbial colonization and health is a rapidly evolving area of investigation. Normalized absolute abundance data is increasingly used in gut microbiome research to accurately reflect community dynamics and avoid compositional artifacts associated with relative abundance data. With relative abundance data, a change in one microbial taxa can significantly affect the apparent abundance of others, resulting in erroneous interpretation of findings. Here, we validated a method for quantifying normalized abundances from human milk 16S rRNA gene sequencing data using a spike-in control, a more efficient and cost-effective alternative to separately performing quantitative polymerase chain reaction. We compared both methods on 30 milk samples from 27 mothers and found no significant differences in community profiles in terms of diversity metrics and total microbial loads. These findings advance normalization strategies to more accurately reflect biological changes in the human milk microbiota.

Background: A disrupted gut microbiome during an infant’s first 1000 days of life can lead to long-lasting negative effects on child health. Cesarean delivery and formula feeding are two factors that can detrimentally impact infant microbiome development as well as maternal mental health. Donor human milk may be a superior supplementation alternative to formula. Research Aim: To examine donor human milk supplementation compared to formula supplementation in full-term infants born via Cesarean section and the impact on the infant gut microbiome, infant health outcomes, breastfeeding outcomes, and maternal mental health. Methods and Planned Analyses: We are conducting a pilot clinical randomized controlled trial, comparing donor human milk to formula supplementation for 187 full-term infants born via Cesarean section who are breastfeeding and require supplementation in the first postnatal week of life. Infant stool samples, breastfeeding outcomes, maternal mental health, and child health outcomes will be measured at 1-week, 3-, 6-, and 12-months postpartum. Additionally, child health and maternal mental health are being assessed at 18- and 36-months postpartum. Discussion: This study will generate essential data on the association between supplementation types and the full-term infant microbiome, breastfeeding exclusivity and duration, and infant health. It will also provide preliminary data to inform a multi-site, longitudinal mixed-methods randomized controlled trial that will assess longer term child health outcomes. This evidence may be used to inform guidelines and policies that will increase accessibility to and raise awareness of donor human milk as a supplementation option in this population.

Background: Processing speed is a foundational skill supporting intelligence and executive function, areas often delayed in preterm‐born children. The impact of early‐life nutrition on gray matter facilitating processing speed for this vulnerable population is unknown.Methods: Magnetic resonance imaging and the Wechsler Preschool and Primary Scale of Intelligence‐IV Processing Speed Index were acquired in forty 5‐year‐old children born preterm with very low birth weight. Macronutrient (grams per kilogram per day) and mother's milk (percentage of feeds) intakes were prospectively collected in the first postnatal month and associations between early‐life nutrition and the primary outcome of brain regions supporting processing speed were investigated.Results: Children had a mean (SD) gestational age of 27.8 (1.8) weeks and 45% were male. Macronutrient intakes were unrelated, but mother's milk was positively related, to greater volumes in brain regions, including total cortical gray matter, cingulate gyri, and occipital gyri.Conclusion: First postnatal month macronutrient intakes showed no association, but mother's milk was positively associated, with volumetric measures of total and regional cortical gray matter related to processing speed in preterm‐born children. This exploratory analysis suggests early‐life mother's milk supports processing speed by impacting structural underpinnings. Further research is needed on this potential strategy to improve preterm outcomes.

Background: The impact of suboptimal intakes on neurodevelopment of very low‐birth‐weight (VLBW, +0 weeks were collected prospectively from VLBW infants (n = 302) enrolled in a previous trial (ISRCTN35317141). Neurodevelopment was assessed by the Bayley‐III at 18 months’ corrected gestational age. Relationships between quartiles of macronutrient/energy intakes, growth, and neurodevelopment were assessed.Results: Infants born P < 0.05). Higher quartiles of energy, lipid, and carbohydrate intakes were positively associated with growth velocity (P = P = 0.001–0.004); however, intakes within the second and third quartiles were generally associated with the highest cognitive scores. No nutrient intakes were associated with language or motor scores across the entire study period.Conclusion: Smaller, more immature VLBW infants and those with morbidity have the greatest risk of poor nutrition and growth. Increasing macronutrient/energy intakes are generally associated with improved weight gain, but not necessarily improved neurodevelopment.

Background: Few studies have examined how maternal body mass index (BMI), mode of delivery and ethnicity affect the microbial composition of human milk and none have examined associations with maternal metabolic status. Given the high prevalence of maternal adiposity and impaired glucose metabolism, we systematically investigated the associations between these maternal factors in women ≥20 years and milk microbial composition and predicted functionality by V4-16S ribosomal RNA gene sequencing (NCT01405547; https://clinicaltrials.gov/ct2/show/NCT01405547). Demographic data, weight, height, and a 3-h oral glucose tolerance test were gathered at 30 (95% CI: 25–33) weeks gestation, and milk samples were collected at 3 months post-partum (n = 113). Results: Multivariable linear regression analyses demonstrated no significant associations between maternal characteristics (maternal BMI [pre-pregnancy, 3 months post-partum], glucose tolerance, mode of delivery and ethnicity) and milk microbiota alpha-diversity; however, pre-pregnancy BMI was associated with human milk microbiota beta-diversity (Bray-Curtis R² = 0.037). Women with a pre-pregnancy BMI > 30 kg/m² (obese) had a greater incidence of Bacteroidetes (incidence rate ratio [IRR]: 3.70 [95% CI: 1.61–8.48]) and a reduced incidence of Proteobacteria (0.62 [0.43–0.90]) in their milk, compared to women with an overweight BMI (25.0–29.9 kg/m²) as assessed by multivariable Poisson regression. An increased incidence of Gemella was observed among mothers with gestational diabetes who had an overweight BMI versus healthy range BMI (5.96 [1.85–19.21]). An increased incidence of Gemella was also observed among mothers with impaired glucose tolerance with an obese BMI versus mothers with a healthy range BMI (4.04 [1.63–10.01]). An increased incidence of Brevundimonas (16.70 [5.99–46.57]) was found in the milk of women who underwent an unscheduled C-section versus vaginal delivery. Lastly, functional gene inference demonstrated that pre-pregnancy obesity was associated with an increased abundance of genes encoding for the biosynthesis of secondary metabolites pathway in milk (coefficient = 0.0024, P_FDR < 0.1). Conclusions: Human milk has a diverse microbiota of which its diversity and differential abundance appear associated with maternal BMI, glucose tolerance status, mode of delivery, and ethnicity. Further research is warranted to determine whether this variability in the milk microbiota impacts colonization of the infant gut.

Data on how baseline characteristics, acuity, morbidity, and nutrition work in combination to affect the growth of very-low-birth-weight (VLBW, 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). 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. 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.

Background: Pasteurized donor milk is the recommended supplement for preterm infants when mother's milk volumes are insufficient. Compared with mother's milk, the macronutrient content of donor milk is thought to be lower due to pasteurization and additional container changes during processing. Given that poor growth is concerning for preterm infants, it is important to understand how processing and feeding methods influence the nutrition composition of donor milk feeds. The research aim of this study was to determine the effects of pasteurization and feeding method on the macronutrient and energy composition of donor milk. Ten donor milk pools were pasteurized, prepared according to neonatal practices, and infused through nasogastric tubes to simulate 4 feeding methods: bolus, 30 minutes, 60 minutes, and continuous feeding over 4 hours. Macronutrient concentrations were assessed after pasteurization, preparation, and each feeding method using a mid‐infrared human milk analyzer. Results: There were no significant decreases in macronutrient content after pasteurization or bolus feeding. However, energy and fat losses increased with slower infusion rates. After continuous feeding for 4 hours, energy and fat concentrations decreased by a mean of 17.3 (15.8–18.8) kcal/dL and 2.08 (1.90–2.25) g/dL (P < .0001), respectively. Conclusions: Pasteurization did not significantly reduce donor milk macronutrient and energy content; however, feeding method significantly impacted the final delivery of energy and fat.

Background: Serious morbidity may elevate nutrient requirements and affect adherence to feeding guidelines for very low birth weight (VLBW) infants. An understanding of factors affecting nutrient intakes of VLBW infants will facilitate development of strategies to improve nutrient provision. Our aim was to examine the impact of neonatal morbidity count on achieving recommended nutrient intakes in VLBW infants. Methods: VLBW infants enrolled in the Donor Milk for Improved Neurodevelopmental Outcomes trial (ISRCTN35317141, n = 363) were included. Serious morbidities and daily parenteral and enteral intakes were collected prospectively. Results: Median intakes of infants with and without ≥1 morbidity met protein recommendations (3.5–4.5 g/kg/d) by week 2, although not maintained after week 4. Infants with ≥1 morbidity (vs without) were 2 weeks slower in achieving lipid (4.8–6.6 g/kg/d; week 4 vs 2) and energy (110–130 kcal/kg/d; week 5 vs 3) and 1 week slower in achieving carbohydrate recommendations (11.6–13.2 g/kg/d; week 4 vs 3). Adjusted hazard ratios of first achieving recommendations on any given day in infants with any 1 or 2 morbidities were 0.6 (95% confidence interval [CI], 0.5–0.9) and 0.6 (0.4–0.9), respectively, for protein; 0.5 (0.4–0.7) and 0.3 (0.2–0.5) for lipid; and 0.5 (0.4–0.7) and 0.3 (0.2–0.4) for energy. Conclusion: Morbidity is associated with a decreased likelihood of achieving lipid and consequently energy recommendations. This and the decline in protein intakes after the early neonatal period require further investigation to ensure optimal nutrition in this vulnerable population.