Is there a word or term for people who have a fear of growth?
At http://www.fun-with-words.com/phobias_o-q.html is a delightful list of 'phobia words'. Perhaps appropriate here is:
obesophobia Fear of gaining weight. [ID, CE]
but probably more relevant is:
prosophobia Fear of progress. [ID, CE, WP]
The references are perhaps not the most authoritative:
ID: The Insomniac's Dictionary of the Outrageous, Odd, and Unusual by Paul Hellweg.
CE: Crazy English: The Ultimate Joy Ride Through Our Language by Richard Lederer.
WP: Words at Play: Quips, Quirks, and Oddities by O. V. Michaelsen. Also in The Wordplay Almanac by O. V. Michaelsen.