A 41-Year-Old Woman, Gravida 1 Para 0, at 21 Weeks

A 41-year-old woman, gravida 1 para 0, at 21 weeks gestation comes to the emergency department due to several hours of vaginal spotting.  She has also had increased vaginal discharge and pelvic pressure over the past few days but no cramping or leakage of fluid.  The patient first felt fetal movement last week and has an occasional headache without visual changes or epigastric pain.  She has chronic hypertension and type 2 diabetes mellitus.  The patient had an abnormal Pap test in her 20s that required a cone biopsy.  She has a 20-pack-year smoking history but quit 2 years ago.  Temperature is 36.7 C (98.1 F) , blood pressure is 130/84 mm Hg, and pulse is 78/min.  BMI is 24 kg/m².  The abdomen is soft and nontender with no palpable contractions.  On pelvic examination, minimal blood is present in the vaginal vault.  The cervix is visibly dilated to 2 cm, with smooth, shiny membranes bulging through the os.  Deep tendon reflexes are 2+ at the knees.  Transabdominal ultrasound reveals the fetus in a cephalic presentation with a low-lying anterior placenta.  Fetal heart rate is 150/min.  Urinalysis shows no protein.  Which of the following is the most likely contributing factor to this patient's clinical presentation?

A) Advanced maternal age
B) Chronic hypertension
C) Cone biopsy
D) Placental location
E) Tobacco use
F) Type 2 diabetes mellitus