A patient wakes at 3 a.m. with light cramping pains every 25 minutes. At 7 a.m. she notes a clear gush of fluid and calls her provider. She arrives at the hospital at 8:30 a.m. and a vaginal exam shows she is 5 cm dilated and 100% effaced. She continues to labor and at 2 p.m. has an overwhelming need to push. She delivers a healthy boy at 3:30 p.m., and the placenta at 3:45 p.m. How long was the first stage of labor?