What causes bleeding during intercourse?

If you want ten good causes they are

Chlamydia
Gonorrhea
Vaginitis
Cervical polyps
Trichononiosis
Yeast infection
Uterine polyps
Fibroid rumors

All ten are common reasons for bleeding during intercourse or it could be, if you noticed new light coloured blood, from rough sex or scratching the vaginal wall with nails during foreplay.