Which groups benefited least from the reforms of the progressive era?

 As in any era where reforms happen, there are winners, and losers. 

The rich, Big Business benefit the most, while the middle and lower classes benefit the least 
The unions benefit in that more people are wont to join for the protection they offer, and for a fair deal. 
Consumers may benefit in the short term, however as we see, prices always go up, and quality always go down. 

Women, Children, and the African Americans are the least groups to benefit, or were many years ago, as they had no real champions for their cause.
Hope this helps