Care must be taken in searching for information on the Internet. Unlike both the print resources found in the library and the electronic databases provided by the library, freely available Internet resources have not necessarily been published by reputable academic publishers nor have they been selected by librarians with expertise in their subject area. Nearly anything can be posted on a website, and just because it is available online does not mean it is valid or authoritative.
However, this does not mean that you cannot find good resources on the Internet; the key to doing so is to carefully evaluate what you find on the web. If you use web resources, be sure to ask these questions:
Turn to these free online primary sources:
Medical Heritage Library
A consortium of medical libraries, including Yale, have put parts of their collections available online. Over 300,000 freely downloadable primary source books, many from 1780-1923. On the Medical Heritage Library website, you can find access to American and State medical society journals.
National Library of Medicine (NLM) Historical Collections
Great primary history of medicine material, including digitized books, images, archives, and moving images (aka movies).
Home to a huge variety of resources, including Moving Pictures, for free use. Not limited to history of medicine, but lots of possible primary sources here. Examples include books you can download or borrow (signing up for a free account) on Christian Science, or Mary Baker Eddy, and others. Make sure, if you pick a source from here, that it's uploaded by a library or other institution!
A huge online repository of freely downloadable books and journals, from a collaboration of libraries including Yale. Not limited to history of medicine, but lots of possible primary sources here on childbirth in America.
Digital Public Library of America
This site pulls in sources and archives (like letters and diaries) from many libraries, museums, and other institutions, as well as big databases like Hathi Trust and Internet Archive.
This is a selected list of sites related to topics involving the history of reproductive health. This is by no means everything!