Scientific background: Uncontrolled gestational diabetes mellitus (GDM) is associated with severe maternal and neonatal morbidities. Treatment of GDM is multidisciplinary and includes lifestyle changes and medications. However, the efficacy of these treatments is limited due to poor motivation, daily painful blood tests and multiple injections.

Probiotic supplements were shown to modulate the gut microbiome by reducing the adverse metabolic effects associated with pathogenic microbial colonization. Promising effects on glycemic control and insulin resistance in non-pregnant diabetic patients were reported. However, the effect of probiotics on glycemic control in GDM has not been elucidated.

Objectives: To examine the effect of a mixture of probiotic strains given daily on maternal glycemic parameters, and pregnancy outcomes among women with GDM.

Working hypothesis: Oral administration of probiotics will be effective in glucose control of patients with GDM and their neonates without causing significant adverse effects.

Type of research and methods of data collection: A prospective randomized, double blind, placebo controlled trial. Women newly diagnosed with GDM will be recruited and followed in the GDM clinic and Maternal-Fetal Medicine ward (including the research clinic) at Emek Medical Center. They will be divided into a research group, receiving the probiotic formula Femina II and a control group, receiving a placebo (2 capsules/day) until delivery. Glycemic control will be evaluated by daily glucose charts. After 2 weeks of diet and probiotic/placebo treatment and thereafter, pharmacotherapy will be started in case of poor glycemic control according to the daily glucose charts. Blood tests for glycated molecules will be performed. Fetal well-being and growth will be assessed. The primary outcomes are:

1. The rate of women requiring medications for glycemic control
2. Mean value of the mean daily glucose charts after 2 weeks of treatment with the study products.

Inclusion Criteria:

• Pregnant women who were diagnosed with GDM from 13 to 32.6 gestational weeks
• 18 years old and older
• Singleton pregnancy

Exclusion Criteria:

• Women with pre-gestational diabetes mellitus
• GDM diagnosed ≥ 33 gestational weeks
• Women using prophylactic antimicrobial treatment
• Immunocompromised women
• Multiple pregnancy
• Women taking oral probiotic products who refuse to stop the consumption (food-containing probiotics is not considered an exclusion criterion).