- 1. History of preterm birth and taking progesterone. Progesterone may influence the microbiota and metabolites so therefore these women will not be eligible for the study. However, if the women fit other inclusion criteria and have a history of preterm birth but are not on progesterone they will be eligible for enrollment 2. History of antibiotic use in the last month (includes pre-biotics and probiotics). These medications will change the baseline microbiota.