A response to Daz Eddy:

Your advice to go slowly to avoid hurting the woman is well taken. There are few cases where the penis is fundamentally too large, but if the woman is nervous, insufficiently lubricated, or rushed, her vagina might not stretch comfortably. However, I do not believe that there are many cases where this causes bleeding! The blood-spot that husbands in some cultures proudly display after the consummation of marriage comes from the hymen, a thin piece of tissue that covers the vagina and is harmlessly destroyed the first time the vagina is substantially penetrated. Many women bleed when this happens; others don't; others had thin hymens that wore away throughout their youth or were broken in an accident or during masturbation or oral sex.

This writeup seems to be getting downvoted. If I am factually incorrect, please let me know! I would really hate to be confused about something like this.