I think the stigma of giving birth to a black baby would have been worse than being a single mom. This was the 60’s and inter-racial marriages or relationships weren’t as common as today.
I’ve just stumbled on to an oddity just now while googling the issue of Frank Marshall Davis being Barry’s father. Someone on yahoo asks the question of whether this is the case and it appears that if you scroll down you see that Frank’s other son Mark Davis replies using the screen name “kaleokualoha”
http://answers.yahoo.com/question/index?qid=20100722132400AAMYtE0
Here’s a link to a photo of Mark Davis - the same as “kaleokualoha” http://my.barackobama.com/page/community/blog/Kaleokualoha
Seems that Mark Davis protests too much. Strange that he trawls the internet responding to random questions on yahoo. Am guessing the birth certificate either has Frank’s name on it or at least reveals blood types consistent w/Frank being the father.