I didn't even know that this wasn't the first time she had lost:
Those old Blue Dog Dems: making KY more Democratic in midterms than in presidential elections!
And for those who were wondering:
KY-49:
Trump 72.3%
Clinton 23.3%
Her loss was almost certainly because of Trump’s coattails (and, in 2012, anti-Obama sentiment).
It's a really weird district to be competitive. This is not a traditionally Democratic part of Kentucky at all; it's middle-income suburbs of Louisville, not a coalfield. It voted for Bob Dole in 1996. I suppose Linda Belcher must be a very strong candidate with the local connections to win over many Republicans, but she gets overwhelmed in Presidential years when more partisan, lower information voters make their appearance. Not specific to Trump or Obama (or Clinton or Romney) in that sense.