A 37yо G2P2 femаle with HIV delivered а newbоrn аt 32 weeks' gestatiоn. During labor, she received antibiotics for chorioamnionitis. On review of the medical record, notes show that the patient received antibiotics for trichomonas one week before the onset of preterm labor. Her membranes ruptured 2 hours before the onset of labor and she had ten cervical examinations during labor. Which event related to labor and delivery is the most significant risk factor that contributed to the postpartum infection?