A 40-year-old G1P0 woman at 22 weeks gestation presents to the office with a complaint

A 40-year-old G1P0 woman at 22 weeks gestation presents to the office with a complaint of pelvic pressure. She reports that she had intercourse the night prior to presentation and noted some mucous mixed with blood this morning. Her history is significant for type 1 diabetes and she is on an insulin pump. Her surgical history is significant for a history of cone biopsy for treatment of abnormal Pap smear three years ago. On examination, her BMI is 26. She is noted to have a 2 cm dilated cervix with bulging membranes that rupture upon placing the speculum. Fetal parts are noted in the vagina. What is the most likely cause of this finding