Results from a case-control study conducted in Tabriz, Iran reveal a near 30 point (significant) difference in depressed postpartum women relative to their non-depressed peers.

To read more on this study:  https://www.google.com/search?source=hp&ei=SGW8XrmUM6mvggfI-ZL4CQ&q=Comparison+of+Maternal+Functioning+between+Iranian+Mothers+with+and+without+Depressive+Symptoms%3A+A+Case-Control+Study&oq=Comparison+of+Maternal+Functioning+between+Iranian+Mothers+with+and+without+Depressive+Symptoms%3A+A+Case-Control+Study&gs_lcp=CgZwc3ktYWIQA1DPCFjPCGCrDGgAcAB4AIABAIgBAJIBAJgBAKABAqABAaoBB2d3cy13aXo&sclient=psy-ab&ved=0ahUKEwi52OqD47HpAhWpl-AKHci8BJ8Q4dUDCAk&uact=5