Regarding the study the author referenced, it was about a certain religious sect that rejected any medical care for childbirth. Here is the citation to the original study:
Kaunitz AM, Spence C, Danielson TS, Rochat RW, Grimes DA. “Perinatal and maternal mortality in a religious group avoiding obstetric care.” Am J Obstet Gynecol. 1984 Dec 1;150(7):826-31.A summer 2003 issue of Midwifery Today had some responses to that study, including these comments:
Midwives who have been working in the freebirth community for these last 25 years have a different story....Many families choosing unassisted birth are highly educated and responsible; their births are a far cry from those that are unattended for reasons of poverty, distrust in medical attendants or ignorance.
~ midwife Jeannine Parvati Baker
There has never been a study done that consisted of data from planned, unassisted births of healthy women who wanted their babies, were in emotionally and physically supportive environments, were somatically aware and comfortable with their bodies, had full access to health care as they needed it and who made the choice freely and gladly. We really don't know (statistically speaking) what happens when the human body is allowed to give birth instinctively and undisturbed under such conditions.