There is, IMO, no question that the US imprisons people for inappropriate things - things that are (again IMO) more appropriately dealt with through medical treatment - for example, personal drug use. This has been accelerating over the past years. It may well be that the approximately double increase in the percentage of female inmates (if one gives credence to the ACLU's figures) over male since the 70s reflects the impact of the Equal Rights movement as much as anything else.

As for the issue of whether or not women should be allowed to have their children, newborn or not, in jail with them? Assuming for the sake of discussion that the mothers should be in there in the first place, and disregarding the related topic of already inadequate space and funding to maintain minimum standards, a prison cell is no place to raise a child.