Peer-reviewed article
Longitudinal modelling of microbiome subcommunities reveals parity-dependent dynamics during pregnancy and postpartum.
K M Kennedy, S Fernando, S A Atkinson, M G Surette, P Jeganathan et al. ·
Summary
Written by AI, not yet AICS's view · claude-haiku-4-5-20251001This is a microbiome research study examining how pregnant women's gut bacteria change during pregnancy and after birth, with focus on how pre-pregnancy weight and number of previous pregnancies affect these changes. The study collected stool samples from 52 pregnant participants across pregnancy trimesters and postpartum, plus infant samples at 6 months. The research found that the gut microbiome maintains stable bacterial communities while their proportions shift differently in first-time mothers versus experienced mothers, and that higher pre-pregnancy weight was associated with less microbiome change.
Key points
- Seven distinct microbial subcommunities were identified that remained taxonomically stable throughout pregnancy but varied in proportion within individuals
- Multiparous women showed greater microbiome shifts early in pregnancy, while primiparous women showed progressive shifts with largest changes after birth
- High pre-pregnancy BMI was associated with reduced microbiome remodelling, particularly in multiparous individuals
- Maternal SCFA-producing bacteria in late pregnancy were positively associated with infant Bifidobacterium dominance at 6 months
- Pre-pregnancy BMI > 25 was independently associated with lower infant Bifidobacterium abundance
Limitations
This is a basic science study of microbiome dynamics and does not evaluate interventions to improve child well-being or health outcomes. The study does not measure clinical child health outcomes, only microbiome composition associations, and therefore cannot demonstrate whether these microbiome differences translate to actual benefits or harms for infant health.
Abstract
BACKGROUND: Dysregulation of maternal adaptations to pregnancy due to high pre-pregnancy BMI (pBMI) is associated with worsened health outcomes for mothers and children. The role of the gut microbiome in these adaptations remains unclear. METHODS: Stool samples were collected from pregnant participants (n = 52) enrolled in the Be Healthy in Pregnancy study (NCT01689961) during first, second, and third trimesters, and 6-months postpartum, along with samples from their infants at 6 months of age. Following 16S rRNA gene sequencing, we implemented time-aligned LDA (TALDA) using a time-weighted sampling strategy with exponentially decaying weights to construct time-proximal cohorts, applied LDA to each cohort independently, and aligned resulting topics using the alto R package. Infant samples were analyzed using standard LDA. RESULTS: Seven distinct subcommunities were identified, one of which represented perineal contamination and was excluded from further analysis. Remaining subcommunities had distinct taxonomic definitions which remained stable throughout pregnancy (mean cross-cohort stability 0.899) while subcommunity proportions within individuals varied. Multiparous individuals showed greater shifts in subcommunity proportions during early pregnancy, while primiparous individuals displayed progressively increasing shifts with the largest changes during the transition from pregnancy to postpartum. High pBMI was associated with reduced microbiome remodelling, particularly among multiparous individuals. In exploratory analyses, maternal SCFA-producing subcommunity abundance at late pregnancy was positively associated with infant Bifidobacterium-dominated subcommunity proportions at 6 months, while pBMI > 25 was independently associated with lower infant Bifidobacterium. CONCLUSION: TALDA effectively distinguished between stable subcommunity definitions and dynamic subcommunity proportions, revealing that the microbiome maintains functional organization while subcommunity proportional contributions shift over the course of pregnancy and postpartum. These maternal dynamics may have intergenerational consequences through their influence on infant gut colonization. This work demonstrates that maternal factors modify microbiome trajectories and supports the existence of an ecological memory of pregnancy history within the maternal gut microbiome.