The Original Studies done by Kennell and Klaus helped to form the first doula training organization, DONA International. This document describes the beginning of the research and evidence based care that birth doulas provide. Scroll down to the part where they talk about ‘Research Findings’.
The research has pretty consistently found the nearly the same significant benefits, though the actual numbers may vary. Understanding Research may help you start to figure out what the numbers mean and how to interpret and disseminate them.
In 2012, Hodnett et al. published an updated Cochrane review on the use of continuous support for women during childbirth. They results of 22 trials that included more than 15,000 women. These women were randomized to either receive continuous, one-on-one support during labor or “usual care.” The quality of the studies was good.
Continuous support was provided either by a member of the hospital staff, such as a midwife or nurse (9 studies), women who were not part of the woman’s social network and not part of hospital staff (doula 5 studies; childbirth educators 1 study, retired nurses 1 study), or a companion of the woman’s social network such as a female relative or the woman’s partner (6 studies). In 11 studies, the husband/partner was not allowed to be present at birth, and so continuous support was compared to no support at all. In all the other studies, the husband or partner was allowed to be present in addition to the person providing continuous labor support.
Another interesting piece to get familiar with is the study by Klein et al. on The Life of the (Canadian) Doula. It is relevant to all doulas on career sustainability.