Has "mother" become politically incorrect?

Solution 1:

Here are the usage stats from the Corpus of Contemporary American English (number of instances per million words, by context):

           SPOKEN  FICTION  MAGAZINE NEWSPAPER ACADEMIC 

mother      281      939      287       253      134 
mom         125      204      102        59        6

And now the same stats sorted by year:

         1990–1994 1995–1999 2000–2004 2005–2009 2010–2012

mother      361       413       382       359       353 
mom          58        94       103       122       139

While we're at it, for a more complete picture, let's also check the Corpus of Historical American English:

^{(X axis: year, Y axis: incidences per million words)}

What we can see is that mom has indeed been gaining ground, but it's nowhere near surpassing mother.

And if you think that mom is more politically correct than mother, you must be forgetting "your mom" jokes.

Solution 2:

Mother is not politically incorrect. Mom is just a shorter, friendlier term for the same person.

Consider the organization Mothers Against Drunk Driving. They're political, but certainly not incorrect.