(1) Metabolites shaped by the maternal microbiome may enter the fetal circulation and affect early neurodevelopment of the fetus during gestation. (2) Metabolites shaped by the maternal microbiome contained in the milk may be ingested by offspring during lactation. (3) Maternal microbiota could affect mothering behavior via the mother’s brain during the early neonatal period. (4) Maternal microbiota could be directly vertically transferred to offspring at birth, and reinforced through coprophagia during the neonatal period. In addition, there are complex interactions between the microbiome, metabolome, immune system, brain, and behavior within offspring as shown in Fig. 2.