montessorimama, you may have heard of these resources, but if not you may find them very helpful!
Have you read Henci Goer's "The Thinking Woman's Guide to a Better Birth"? If not, it has some really good reasons why not to do many interventions. I don't know if your DH would be willing to read it, but maybe if you just happened to be reading it and read him some quotes that would be a good thing...
Also, "A Guide to Effective Care in Pregnancy and Childbirth" is very useful, and is based on clinical trials. They have a great summary in Ch 50 that distinguishes between Forms of Care Likely to be beneficial, with trade offs, unknown, unlikely to be beneficial, and likely to be ineffective or harmful. Then, if you want to see why something specific is categorized the way it is, you can look in the book for explanations and details. Childbirth Connection has the whole book in pdfs: http://www.childbirthconnection.org/article.asp?ck=10218
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