This is something we can fix. We don't have to wait for anyone else "important" to make a plan, and we don't need expensive drugs. What we need is networking and the determination to repair this gap in the social fabric. The few women with solid biochemical imbalances will hopefully be handled by the health care system. The social system should be able to push those numbers to a biological minimum. This would not only save a lot of misery, it would save considerable money as well. It can be done, because other cultures are managing to do it quite well.
Do you know a woman who is expecting? Talk with her and see if she would like some help after the baby arrives. Figure out where your skills could be useful -- are you good at doing laundry, cooking, watching older children, yardwork? If the expectant mother is a member of your family or very close circle of friends, push hard to arrange support for at least a month; longer is better. This is especially important for first-time mothers who will benefit from having an older female relative or friend with parenting experience. Some women may not want this, but common sense and cultural comparisons indicate that it's a really good idea we should be doing more often, for as many people as will do it. For that matter, social support for new fathers is probably a good idea too.
Are you an employer, or do you have the ear of one? Encourage a family-friendly policy for parental leave. An employee strung out on lack of sleep and baby stress is not going to do your company much good. Make sure they have leave so they can return to work refreshed by the new life in their family. In a really big company, especially if it's one with a lot of female employees, you might talk about the interface between family and work, and how social networks can support both. Maybe if people hear the idea of social support for new mothers, they'll get together and plan something with each other. You could also have a little party when someone goes on parental leave, and make sure to welcome them back when they return. Customs differ in various places, so don't push too hard, but see what kind of things people are open to in your area.
This sort of thing isn't easy. I can remember that it was going on in my area about 30 years ago, though, because my grandmother and her friends talked about making arrangements for new mothers. I've made a few attempts in that direction myself, with only minor success. It's not really my strong suit. But I can keep trying -- and I can put the word out.