I suspect this will now be the "cause" of every man who suddenly becomes totally useless once a baby arrives, totally unable to do night feeds or comfort a crying newborn.
Cue hundreds of threads of women on MN crying their eyes out because they feel awful for minimizing their DH's PND but they'd really like some help and are drowning in infant care, and cue hundreds of responses saying "depression is so hard, you need to understand that he's going through a rough time and may not be able to be his best right now."
Also cue men saying they simply MUST continue to devote as much time to their hobbies after a child is born, because they're staving off PND, how noble of them! And wives feeling blackmailed into letting it happen, even if they get no time to themselves because of it, because forcing him to stay home more and take care of his child would be tantamount to triggering his depression.
"Man depression" is like "man flu." Yes, men sometimes get the flu. Yes, men sometimes get depressed. But there's a certain kind of man who thinks every sniffle is the flu and that he gets to be royalty spending his time in bed all day for a week, while his poor wife with the same sniffle has to do everything she normally did AND wait on him hand and foot.
Similarly, there's "man depression" that somehow manifests as men being able to do everything they have a serious interest in, while neglecting any unpleasant or boring duties and obligations. They'll be able to devote dozens of hours a week to preferred activities, even those requiring the kind of focus and dedication not usually associated with clinical depression, but unable to do responsible, grownup things that aren't fun or nice.
For every man who has something like actual PND, ten will have "man depression." You'll start to see the threads within the year, watch. In fact, it's already starting -- women who talk about their husbands becoming self-centered and irresponsible after the birth of a baby are now told by well-meaning posters, "Are you sure he doesn't have PND?", because making excuses for men is what some women have been trained to do from birth.