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Session: Nutrient Status and Supplementation in Life's Beginnings (Oral 30)

(OR30-06-24) Heat Stress and Micronutrient Insufficiency Effects on the Gut Microbiome and Associations With Maternal-Fetal Outcomes

Monday, July 1, 2024
5:00 PM – 5:12 PM CT
Location:  W375A
Objectives: Micronutrient deficiencies are prevalent in pregnant women worldwide and associated with diminished fetal growth. Climate change (e.g. heat stress) also impacts human health and food supply, which further exacerbates the effects of poor nutrition on maternal-child health. The objective of this study was to examine the interactions between marginal depletion of micronutrients and modest heat during pregnancy on the maternal gut microbiome and its impact on fetal growth.

Methods: C57BL6/J mice (n=6-8/group, 8-week-old) were fed AIN-93G (CON) or a modified AIN-93 diets containing 70% mineral, micronutrient, and vitamin mix (70MMV) ad libitum for 4 weeks. Plug positive females were housed at either 22⁰C or 33⁰C in an environmental chamber during pregnancy, with their respective diets. Samples were collected at dpc 17.5. Cecal microbiome was assessed via 16S rRNA amplicon sequencing. Serum micronutrients were assessed via ICP-MS. Genus level taxa were associated to maternal and fetal outcomes using sparse partial least squares (sPLS) modeling.

Results: Mildly reduced serum K, Fe, Zn, and Se levels showed either diet or temperature effects (p≤0.05). Fetal and placental weights showed a significant diet and temperature interaction, with the 70MMV-33C group having significantly lower weights. The 70MMV-33C group also showed the lowest alpha diversity relative to other groups. Beta diversity showed significant diet and temperature effects. In addition, within the combination group (70MMV-33C), lower abundance of Dorea, Lactobacillus, Dehalobacterium, Ruminomoccus, Lactococcus, and Bacteroides genera was observed. Lastly, modest negative correlations were identified with Ruminococcus and Bacteroides with fetal weights and fetal/placental ratio. Lactobacillus showed a modest positive correlation with serum Zn levels.

Conclusions: Our results show an interaction between modest heat and marginal depletion of micronutrients during pregnancy with changes in the maternal gut microbiome and fetal growth restriction, highlighting an emerging connection between maternal nutrition and heat stress. Data also show a potential role of the maternal gut microbiome and fetal growth.

Funding Sources: CU-Department of Pediatrics, NIH/NCATS Colorado CTSA, & USDA-ARS