Well, I found this:
http://www.btinternet.com/~allan_raymond/Schaumburg_Lippe_Royal_Family.htmSee 27.2411 - The early death of Karoline is shrouded in some mystery, some sources say she died in childbirth and other say she took her own life. Her husband Wilhelm Ernst was known to be a sadist and on the day of his abdication was advised he was the "most unpopular prince in Germany".
and this: Citations from this site:
http://thepeerage.com/p10399.htm 1. [S3] Marlene A. Eilers, Queen Victoria's Descendants (Baltimore, Maryland: Genealogical Publishing Co., 1987), page 161. Hereinafter cited as Queen Victoria's Descendants.
2. [S12] C. Arnold McNaughton, The Book of Kings: A Royal Genealogy, in 3 volumes (London, U.K.: Garnstone Press, 1973), volume 1, page 335. Hereinafter cited as The Book of Kings.
3. [S12] C. Arnold McNaughton, The Book of Kings, volume 1, page 336.
4. [S12] C. Arnold McNaughton, The Book of Kings, volume 1, page 253.