[Pseudoscience-is-malarkey (OP)]

A new parent has to deal with extreme lifestyle changes: less time for themselves, sleep deprivation, monetary issues, loss of freedom, toppled with a preexisting brain chemical imbalance. How important are these factors in your opinion?

[alancalverd]

The environmental factors are all important but to some extent also applicable to male partners, most of whom step up to the plate but a significant number run away. I wonder how the male statistics stand up against those for female PPD?

"Brain chemical imbalance" looks like pseudomedicine, to be followed by a list of ancient curative herbs and potions. There are certainly profound hormonal changes throughout pregnancy and early post-partum, but a species (or even a genetic line within that species) in which these ultimately led to the incapacity or unwillingness of the mother to nurture the baby,  would quickly  become extinct. We know of occasional rejections among farm animals but their lifestyle changes are far less profound than for humans, and the inherent commitment to the newborn is much shorter.

In summary, I've seen it, I don't know the answer, a bit of statistical analysis might be interesting, and I'd counsel against using language that might be construed as "alternative".