Umbrella review of the effectiveness of probiotic supplementation on oxidative stress markers, inflammatory biomarkers, and pregnancy outcomes in pregnant women

Probiotics are considered safe for reducing oxidative stress and inflammation in pregnancy, but meta-analytic findings are inconsistent. This study summarizes evidence on the effects of probiotic/synbiotic on oxidative stress, inflammatory markers, and pregnancy outcomes. An umbrella review was conducted using PRISMA guidelines. PubMed, Scopus, and Web of Science were searched up to April 2025. Outcomes assessed included malondialdehyde (MDA), total antioxidant capacity (TAC), glutathione (GSH), nitric oxide (NO), interleukin‑6 (IL‑6), tumor necrosis factor‑alpha (TNF‑α), C-reactive protein (CRP), high-sensitivity CRP (hs‑CRP), GDM, preeclampsia, preterm birth, cesarean section, birth weight, and gestational age. Thirty-eight meta-analyses involving 37,195 participants were included. Probiotic supplementation consistently reduced MDA and improved antioxidant capacity (TAC, GSH), though findings for NO were mixed. Several meta-analyses reported significant reductions in IL-6, TNF-α, and hs-CRP. However, probiotics showed no consistent effect on clinical outcomes such as GDM, preeclampsia, preterm birth, cesarean section, or birth weight. Considerable heterogeneity was observed across probiotic strains, dosages, and intervention durations. Probiotic supplementation during pregnancy appears to improve several biomarkers of oxidative stress and inflammation. However, current evidence does not consistently demonstrate beneficial effects on major clinical pregnancy outcomes. These findings suggest that while probiotics may influence biological pathways related to oxidative balance and inflammation, further high‑quality randomized controlled trials are needed to determine whether these biochemical effects translate into meaningful clinical benefits for maternal and neonatal health. Not applicable.