These are excerpts from some of the research quoted in, "Birthing from Within."

This is from a 1976 study of matched low-risk mothers (1046 planning home births with 1046 planning hospital births):

• The hospital birth women were more likely than the home birth mothers to have had the following: five times more likely to have high blood pressure in labor, nine times more likely to have a severe perineal tear, three times more likely to have had postpartum hemorrhage, and three times more likely to have had a Cesarean. 
• The babies born to the hospital birth women also had a higher complication rate than the babies born to home birth women.  In the hospitals, the infants were six times more likely to have had fetal distress before birth, four times more likely to have needed assistance to start breathing, and four times more likely to have developed an infection.  There were no birth injuries at home, but 30 infants in the hospital suffered birth injuries.

This is from a 1991 hospital study.