Depends on severity. And any past history of depression, post-partum or otherwise. It is absolutely imperitive that a woman, post partum, experiencing any degree of depression, get a medical evaluation right away to determine what type of intervention is needed to deal with that depression. That intervention may include antidepressant medication and probably counseling as well. It's too serious a problem to ignore.
Yes. There are "shades of grey" when it comes to post-partum blues to post-partum depression to post-partum psychosis. There is a good chance that an anti-depressant will relieve the symptoms of the depression. It is often a medication that you'll take for only 3 months.