Mothers who give birth at NYULMC or Bellevue Hospital and comply with the inclusion and exclusion criteria for exposure to maternal vaginal contents can choose to expose their newborn to samples of their vaginal microbiome just after birth. Such mothers will be tested to confirm that their vaginal pH is acidic (pH ≤ 4), which indicates the dominance of lactic acid bacteria. Testing of vaginal pH will be performed using pH paper. These procedures require of the presence of a study member and will only be performed at NYULMC or Bellevue hospitals.