Antimicrobial therapies, while important for treating infections in mothers and their newborns, have not reduced PTB rates. In addition, the overuse of antibiotics has been shown to disrupt the transfer of health microbes from the mother to her infant during and after birth. By improving our understanding of haw maternal microbes contribute to fetal and infant health, BLOOM-PTB hopes to identify new strategies for preventing infection-related PTB, while safeguarding the health process of microbial transfer from a mother to her infant.