Pregnancy is a critical window for metabolic health, and early changes in blood sugar regulation can increase the risk of gestational diabetes mellitus (GDM), which affects both maternal and infant health. At the same time, the maternal gut microbiome changes throughout pregnancy and may play a role in glucose metabolism and insulin resistance. Kefir, a fermented milk drink containing beneficial bacteria and yeasts, may be a simple dietary strategy to support metabolic health during pregnancy, but its role in preventing GDM has not been well studied.
This study will test whether drinking kefir daily from mid-pregnancy until routine GDM screening can improve glucose and insulin regulation, reduce the incidence of GDM, and modulate the maternal gut microbiome and metabolites, among other outcomes.
Pregnant individuals will be randomly assigned to either a kefir group or a control group receiving usual prenatal care. Researchers will collect blood glucose and insulin measures, dietary information, stool samples, and body composition data across pregnancy and postpartum to evaluate metabolic and microbiome-related changes.
As one of the first studies to examine kefir as an early pregnancy intervention for GDM prevention, this study will help clarify whether a practical, food-based approach can improve maternal metabolic health. The findings may support future nutrition strategies aimed at reducing GDM risk and improving pregnancy outcomes.
Pregnant individual with a singleton pregnancy
19 years and older of age
Gestational age 14,3 weeks or less at enrolment
Able and willing to attend four in-person study visits at the PEADS Laboratory: baseline, 18-20 weeks' gestation, 26-28 weeks' gestation, and 1 month postpartum
Pre-existing metabolic disease affecting glucose regulation, including type 1 diabetes or type 2 diabetes
Current use or first trimester use of medications known to alter glucose metabolism, such as metformin or semaglutide
Gastrointestinal or inflammatory disease, including Crohn's disease, ulcerative colitis, celiac disease, or diagnosed irritable bowel syndrome
Allergy, intolerance, or other contraindication to dairy or components of kefir
Parallel
Kefir
Dietary supplementKefir is a fermented dairy beverage containing a complex host of live bacteria and yeasts. In this study, participants assigned to the intervention group will consume 250 mL of kefir daily from approximately 14 weeks' gestation until the routine GDM screening window at 26-28 weeks' gestation. Participants will otherwise continue their usual prenatal care and habitual diet.
Maternal Fasting Glucose Concentrations
Between-group difference in maternal fasting glucose concentrations measured at baseline (14 weeks' gestation) and during pregnancy via glucose challenge testing conducted within the respective screening window (18-20 weeks' gestation for high-risk or 24-28 weeks' gestation for high-risk and/or low-risk).
Maternal hbA1c Concentrations
Between-group difference in maternal hbA1c concentrations measured at baseline (14 weeks' gestation) and during pregnancy conducted within the respective screening window (18-20 weeks' gestation for high-risk or 24-28 weeks' gestation for high-risk and/or low-risk).
Maternal Fasting Insulin Concentrations
Between-group difference in maternal fasting insulin concentrations measured during pregnancy at the respective screening window (18-20 weeks' gestation for high-risk or 24-28 weeks' gestation for high-risk and/or low-risk).
Maternal Insulin Area Under the Curve
Between-group difference in maternal insulin area under the curve measured during pregnancy at the respective screening window (18-20 weeks' gestation for high-risk or 24-28 weeks' gestation for high-risk and/or low-risk).
Gut Microbiome Diversity and Composition
Gut microbiome diversity and taxa will be assessed using metagenomic sequencing of stool samples collected from participants. Alpha diversity metrics (e.g., Shannon index, Chao1) and beta diversity metrics (Bray-Curtis dissimilarity) will quantify within- and between-sample microbial diversity. Taxonomic composition at phylum, family, and genus levels will be examined.
Gut Microbiome Metabolites
Microbial metabolite profiles relevant to inflammation and metabolic regulation such as short-chain fatty acids will be examined.
Maternal Weight
Maternal weight will be measured at each study visit.
Maternal Height
Maternal height will be measured at baseline.
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