BACKGROUND AND PURPOSE:

• WHO probiotics definition: “live microorganisms which when administered in adequate amounts confer a health benefit on the host”
• There are various probiotics with specific species and strains
• Most common probiotics used are members of Lactobacillus,  Bifidobacterium, and Enterococcus genera
• In an update to a 2014 review, Davidson et al. (Cochrane Database for Systematic Reviews, 2021) assessed the effects of probiotic supplements used either alone or in combination with pharmacological and non-pharmacological interventions on the prevention of GDM

METHODS:

• Systematic review and meta-analysis
• Data sources
  • Cochrane Pregnancy and Childbirth’s Trials Register | ClinicalTrials.gov | WHO International Clinical Trials Registry Platform (ICTRP)
  • References of studies also reviewed  
  • Through to March 2020
• Study inclusion criteria
  • Randomized and cluster‐randomized trials
  • Studies that compared the use of probiotic supplementation with either placebo or diet for the prevention of GDM
• Study design
  • Two independent review authors: Assessed study eligibility, extracted data and assessed risk of bias of included studies
• Primary outcomes
  • GDM diagnosis
  • Hypertensive disorders of pregnancy
  • Cesarean delivery
  • Large for gestational age (LGA) neonate
  • Mortality or morbidity composite

RESULTS:

• 7 trials | 1647 participants
  • Some variability in studies based on inclusion related to maternal weight
  • All studies compared probiotics with placebo
• Risk of bias
  • Generally low risk of bias | One study had an unclear risk of bias

Probiotics and Maternal Outcomes Including Risk Of GDM, Hypertensive Disorders of Pregnancy, and Cesarean Delivery

• GDM: Uncertain if probiotics have any effect
  • Mean risk ratio (RR) 0.80 (95% CI, 0.54 to 1.20)
  • 6 studies | 1440 participants
  • Low‐certainty evidence
• Preeclampsia: Probiotics increase risk
  • RR 1.85 (95% CI, 1.04 to 3.29)
  • 4 studies | 955 women
  • High‐certainty evidence
• Hypertensive disorders of pregnancy: Probiotics may increase risk  
  • RR 1.39 (95% CI, 0.96 to 2.01)
  • 4 studies | 955 women
  • However, wide CI indicates that probiotics may have no effect
• Cesarean: Probiotics make little to no difference
  • RR 1.00 (95% CI, 0.86 to 1.17)
  • 6 studies | 1520 women
  • High‐certainty evidence
• Maternal weight gain during pregnancy: Probiotics make little to no difference
  • MD 0.30 kg (95% CI, –0.67 to 1.26)
  • 4 studies | 853 women
  • Moderate‐certainty evidence

Probiotics and Neonatal Outcomes Including Risk of LGA, Mortality and Morbidity

• LGA incidence: Probiotics probably make little to no difference   
  • RR 0.99 (95% CI, 0.72 to 1.36)
  • 4 studies | 919 infants
  • Moderate‐certainty evidence
• Neonatal adiposity: Probiotics may make little to no difference
  • Adiposity as fat mass: MD –0.04 kg (95% CI, –0.12 to 0.04)
  • 2 studies | 320 infants
  • Data not pooled; low‐certainty evidence

Additional Outcomes

• Probiotics have an unknown effect on
  • Perinatal mortality 
  • A composite measure of neonatal morbidity 
  • Neonatal hypoglycemia 
• No included studies reported on perineal trauma, postnatal depression, maternal and infant development of diabetes or neurosensory disability

CONCLUSION:

• There was no clear effect of probiotics on GDM risk (low-certainty evidence)
• However, there was a clear link between probiotics and an increased risk for preeclampsia (high-certainty evidence)
• The authors suggest caution in taking probiotics in pregnancy, due to the risk of harm and limited evidence of benefit

Learn More – Primary Sources:

Probiotics for preventing gestational diabetes

Related ObG Topics:

Does Probiotic Use Reduce Risk of GDM in Obese Pregnant Women?

Could Probiotic Milk Reduce Pregnancy Risks?

Does Folic Acid Supplementation Before Pregnancy Reduce Risk of Gestational Diabetes?