Table 3.

Summary of included articles investigating the impact of probiotic supplementation during pregnancy on measures of the intestinal microbiome composition and diversity in their infants (n = 17). Where multiple articles have been published within the same study cohort, these have been grouped together

Author, year	Probiotic	Administration and timing	Infant age	Impact of probiotic supplement on infant microbiome composition and/or diversity
Abrahamsson 2009 81	Lactobacillus reuteri	Mothers: daily from 36 weeks’ gestation until delivery. Infants: daily from 1–3 days until 12 months of age.	5 days 1 month 3 months 6 months 12 months	Lactobacillus reuteri prevalence was significantly higher in the probiotic group compared to placebo at 5 days of age detected in 82% vs 20% (P < .001). After this, the prevalence of Lactobacillus reuteri declined despite continuous supplementation in infants and a high compliance rate.
Avershina 2016,82 Dotterud 2015 83	Lactobacillus rhamnosus GG, Bifidobacterium animalis subsp. lactis Bb-12, and Lactobacillus acidophilus La-5	Mothers: daily from 36 weeks’ gestation until 3 months postpartum.	10 days 3 months 12 months	Lactobacillus rhamnosus GG colonized infants in the probiotic group with greater relative abundance at 10 days (P < .005) and 3 months (P < .005) of age, compared to controls. This difference was not maintained at 12 months (P = .783) or 2 years (P = .511). No statistically significant differences were found between the probiotic and placebo groups in the a- or b-diversity of the total microbiota in infant stool samples at 3 months or 2 years of age.
Bisanz 2015 84	Lactobacillus rhamnosus GR-1	Mothers: daily from 12–24 weeks’ gestation until 1 month postpartum.	3 days 1 week 1 month	Infants aged 10–25 days whose mothers received probiotics had a 3-fold increase in relative abundance of Bifidobacterium and a 16.8-fold decrease in Enterobacteriaceae (P < .05), compared to controls.
Enomoto 2014 85	Bifidobacterium longum BB536 and Bifidobacterium breve M-16 V	Mothers: daily from 36 weeks’ gestation until delivery. Infants: daily from 1 week until 6 months of age.	4 months 10 months	At 4 months of age, the relative abundance of Bacteroidetes was significantly higher in the microbiota of infants in the probiotic group compared to the control group (P = .025). No difference was measured in the stool samples obtained at 10 months of age (P = .770).
Grönlund 2007,86 Grönlund 2011 87	Lactobacillus rhamnosus with Bifidobacterium longum (or) Lactobacillus paracasei with Bifidobacterium longum	Mothers: daily from 15 weeks’ gestation until 6 months postpartum or cessation of exclusive breastfeeding.	1 month 6 months	Correlations between mothers’ and infants’ fecal Bifidobacterial counts determined by quantitative real-time PCR were not affected by probiotics during supplementation at 1 month (P = .11 for Bifdobacterium, P = .40 for B. longum) but were significant at 6 months, after probiotics were ceased (P = .043 for Bifidobacterium, P = .023 for B. longum). Bifidobacterial diversity indexes were not significantly different between infants in probiotic or control groups (P not provided).
Grześkowiak 2012 88	Lactobacillus rhamnosus with B. longum strain BL999 (or) Lactobacillus paracasei with B. longum strain BL999	Mothers: daily from 2 months before delivery until 2 months postpartum.	6 months	At genus level, Bifidobacterium counts were significantly different among the study groups (P = .017), lowest in the Lactobacillus rhamnosus group compared to placebo. The relative abundance of Bifidobacterium was not significantly different between groups (P = .642). In infants whose mothers were supplemented with Lactobacillus rhamnosus compared to placebo, there was a significant difference in the relative abundance of the Lactobacillus-Enterococcus group (P = .003). No other statistically significant differences were found between probiotic and placebo groups regarding the relative abundance of major bacterial groups studied (Prevotella, Clostridium histolyticum and Akkermansia muciniphila).
Gueimonde 2006 89	Lactobacillus rhamnosus GG	Mothers: 2–4 weeks before delivery until 3 weeks postpartum. Frequency of delivery not further specified.	5 days 3 weeks	At 5 days of age, infants whose mothers received L. rhamnosus GG were significantly more likely to be colonized with B. breve (P = .044) compared to the placebo group. This effect did not persist until 3 weeks (P = .069) and there were no other significant differences between groups for other Bifidobacterium species tested. L. rhamnosus GG supplementation in mothers did not significantly increase gut bifidobacterial diversity in infants at 3 weeks (P = .134).
Ismail 2012 90	Lactobacillus rhamnosus GG	Mothers: daily from 36 weeks’ gestation until delivery.	7 days	Prenatal supplementation with Lactobacillus rhamnosus GG had no significant effect on fecal microbial diversity in 7 day old infants, assessed using terminal restriction fragment length polymorphism using restriction enzymes Sau96I and AluI (AluI 14.4 vs. 15.5, P = .17, 95% CI −0.4, 2.5; Sau96I 17.3 vs. 15.8, P = .15, 95% CI −3.5, 0.5).
Korpela 2018 91	Bifidobacterium breve, Propionibacterium freundenreichii subsp. shermanii JS, Lactobacillus rhamnosus and Lactobacillus rhamnosus GG. Infants 1.supplemented with the same probiotic and prebiotic galactooligosaccharides	Mothers: daily from 35 weeks’ gestation until delivery. Infants: daily from birth until 6 months of age.	3 months	The probiotic supplement had a strong overall impact on the microbiota composition, but this depended on the infant’s diet, and the specific effect of maternal probiotic supplementation was not possible to measure. In breastfed infants, those supplemented with probiotics had a greater relative abundance of Lactobacilli (100%) and Bifidobacteria (29%) compared to controls (P < .0001). Other taxa were reduced in abundance in the probiotic group: Clostridia by 66% (P < .0001) and Gammaproteobacteria by 58% (P < .0001). In formula-fed infants, the total abundance of Bifidobacteria was slightly but significantly decreased in those supplemented with probiotics (by 7%, P < .0001). Several Firmicutes and Proteobacteria taxa were also increased in the formula-fed supplemented group compared to the formula-fed control group: Anaerostipes by fourfold (P = .05), Veillonella by sevenfold (P < .0001) and Klebsiella by sixfold (P = .05).
Kukkonen 2007 92	Lactobacillus rhamnosus GG, L rhamnosus, Bifidobacterium breve and Propionibacterium freudenreichii ssp. Shermanii JS Infants supplemented with the same probiotic and prebiotic galactooligosaccharides	Mothers: twice daily from 36–38 weeks’ gestation until delivery. Infants: once daily from birth until 6 months of age.	Meconium 3 months 6 months	At 3 and 6 months, the probiotic group was significantly more frequently colonized with Lactobacilli and Propionibacterium (P < .001). Fecal counts of total Bifidobacteria (P = .001) and Lactobacilli (P < .01) were significantly higher at 6 months. At 2 years, no differences were observed between study groups in fecal bacterial colonization.
Niers 2009,93 Rutten 2015 94	Bifidobacterium bifidum, Bifidobacterium lactis and Lactococcus lactis	Mothers: daily from ~32 weeks’ gestation until delivery. Infants: daily from birth until 12 months of age.	1 week 2 weeks 1 month 3 months 12 months	At time of supplementation, probiotic species had a higher abundance and prevalence in the probiotic group, but this difference was not maintained after supplementation was stopped. Bifidobacteria were significantly higher in the probiotic group at 1 month of age (P = .003) and Lactococcus lactis was significantly higher at 2 weeks (P = .001) and 1 month of age (P = .03). Lactococcus lactis was absent in the placebo group during the intervention period and was significantly higher in abundance at two years (P = .01).
Parnarnen 2018 95	Lactobacillus rhamnosus LPR and Bifidobacterium longum (or) Lactobacillus paracasei and Bifidobacterium longum)	Mothers: daily from 2 months before and 2 months after delivery.	1 month 6 months	No significant changes were observed in the abundance of antibiotic resistance genes in the infants between probiotic and placebo groups.
Rinne 2005,96 Rinne 2006 97	Lactobacillus rhamnosus GG	Mothers: daily from 36 weeks’ gestation until delivery. ± Infants: daily from birth until 6 months of age.	3 months 6 months 12 months	Total bacterial counts in fecal samples showed a decreasing trend from 3 to 12 months of age (P < .0001) which were not different between probiotic and placebo groups (P = .70). At 6 months, there were less Clostridia in feces in the placebo compared with the probiotic group (P = .026). No other statistically significant differences were found between placebo and probiotic groups at 6 months in Bifidobacterium (P = .145), Bacteroides (P = .882), Lactobacillus/Enterococcus (P = .817) and total bacterial counts (P = .125).