Metabolism, Breastmilk, and Microbiome

The incidence of both obesity and diabetes are on a staggering rise. Many studies suggest
that by 2030, 40-50% of the population will be obese. The prevalence of gestational diabetes
(GDM) is also increasing, and was recently reported to be 9%. GDM increases risk of obesity
and impaired glucose tolerance in their children, but the mechanisms by which this occurs are
not well defined.

The benefits of breastfeeding are numerous, including protection from sudden infant death and
infection, positive cognitive outcomes, reduced prematurity complications, and decreased risk
of cancer, as well as some evidence of protection against child obesity. One area that has
yet to be thoroughly explored is whether there are differences in breast milk composition in
women with diabetes as compared to non-diabetic women after adjusting for obesity and other
diabetes co-morbidities, and how these differences could affect infant metabolic health and
body composition. Experimental studies argue strongly for a causal relationship of the gut
microbiome to the risk of obesity and diabetes. Breast milk strongly shapes the gut
microbiome, as it contains unique oligosaccharides as well as hormones and immunologic
factors that cultivate the growth of specific microbiota in the infant gut. Indeed over 90%
of early infant fecal bacteria are Bifidobacteria, where in most formula-fed infants
Bifidobacteria are non-detectable, which has been linked to the rapid growth and greater
adiposity in formula-fed versus breastmilk-fed infants. Given that most pregnant women in the
United States are now either overweight, obese, or diabetic, our study has high public health
significance in that it seeks to understand how maternal metabolic factors such as these
hinder the development of a healthy gut microbiome during the critical period of infancy.

In this study, the following study questions will be examined:1) does maternal metabolic
state relate to the milk microbiome (bacterial and fungal diversity and abundance
relationships, and microbiome function) and how they are transmitted to the infant gut? 2)
does maternal metabolic state relate to the concentration of appetite and growth-regulating
hormones and cytokines present in breast milk?; 3) are maternal serum concentrations of
hormones and milk microbiomes associated with each other?; and 4) are milk hormones and/or
milk microbiomes related to infant growth and body composition in the first 6 months of life?

Amplicon-based and deep (shotgun) metagenomic sequencing will be utilized to characterize
species and strain level characteristics of maternal milk and infant fecal microbiomes. ELISA
assays will be used to quantify adipose-tissue derived hormones (leptin, adiponectin) and
immune factors (CRP, IL-6, TNF-α) as well as insulin/growth axis hormones (insulin, IGF-1,
IGFBP-3) in breast milk. Infant body composition will be assessed using air displacement
plethysmography and dual energy x-ray absorptiometry.

The above work will involve new recruitment enrollment, and pregnancy data collection from 50
diabetic mothers recruited through the Maternal Fetal Medicine and Women's Health Specialists
at M Health. The pregnant non-diabetic (normal weight and obese) woman cohorts (and their
infants and samples) for this study already exist as part of Clinical Trial NCT03301753
(Maternal Obesity, Breast Milk Composition, and Infant Growth (MILK) study), which is
currently in the sample collection phase. The current study will form the first comprehensive
comparison of multiple aspects of breastmilk composition in women with pregnancy diabetes as
compared to non-diabetic women.

Inclusion Criteria:

(For new enrollment of 50 pregnant women with gestational diabetes and their infants.
Enrollment of normal weight and obese cohort comparators already accomplished under
ClinicalTrial NCT03301753):

1. Pregnant women

2. age 21-45 at time of delivery

3. report during enrollment procedures that they have social support for and intention to
exclusively breastfeed for at least 3 months (breastfeeding intentions are known to be
correlated with actual behavior), and if parity >1, that they successfully breastfed
after a previous pregnancy for at least 3 months

4. singleton pregnancy

5. known gestational diabetes Definition of Gestational Diabetes: 1) an elevated glucose
challenge test >200 mg/dL or 2) two abnormal values on the glucose tolerance test
according to Carpenter-Coustan criteria.

Exclusion Criteria:

1. alcohol consumption >1 drink per week during pregnancy/lactation

2. tobacco consumption during pregnancy/lactation,

3. inability to speak/understand English

4. known congenital metabolic, endocrine disease, or congenital illness affecting infant
feeding

5. planned delivery at a site other than the University of Minnesota Medical Center- West
Bank campus.

6. preexisting diabetes