Table 1.

Representative studies examining maternal and infant microbiomes in pregnancy

Study type	Microbiome niche	Key findings	Clinical relevance	Limitations	Ref
Human cohort (91 pregnant women)	Maternal gut	3rd trimester → ↑Proteobacteria, Actinobacteria; ↓diversity	Associated with insulin resistance, inflammation	Small cohort, observational	[37]
Human cohort (1,500 samples)	Vaginal, gut, saliva	Vaginal microbiota shifts predict preterm birth	Early diagnostic potential	Regional population	[65]
Human cohort (Pregnancy & diet study)	Gut	Women with GDM → ↑ Enterobacteriaceae, ↓ Akkermansia	Links to hyperglycemia, maternal metabolic health	Cross-sectional	[66]
Mouse model	Gut	Dysbiosis induced hypertension and PE-like features	Mechanistic insight for preeclampsia	Translational gap	[67]
Human placental samples	Placental	Detected low-biomass microbes; possible contamination	Debate over placental microbiome existence	Contamination risk	[68]
Human cohort	Gut	Dysbiosis → linked to preeclampsia and systemic inflammation	Suggests gut-immune axis role in PE	Small sample size	[69]
Review + meta-analysis	Maternal gut/vaginal	Vaginal microbiota stability is protective against PTB	Vaginal microbiome as a biomarker	Heterogeneous studies	[36]
RCT	Maternal gut & infant gut (diet + probiotics)	Infant α-diversity is lower in the intervention group; maternal Prevotella ↑	Shows maternal diet/probiotic combo can modulate early gut microbiota	Short follow-up; small sample size	[70]
Cohort (36 mothers, 32 infants)	Maternal & infant stool samples	Mode of delivery, gestational age, and breastfeeding strongly influence infant microbiota; maternal changes postpartum	Helps identify modifiable birth/delivery practices	Small cohort; short duration	[71]
Observational	Maternal stool	Trends that specific nutrients (macro/micro) affect maternal gut diversity; the influence varies with risk status	Points to dietary counselling as an intervention potential	No causality; diversity measures only	[72]