Marital conflict. Solving areas of conflict prior to pregnancy and delivery significantly reduces your risk of post partum depression
Stressful life events in the previous 12 months. While you may not be able to control some events around you, if you are having significant stress, try just holding off pregnancy planning for a brief bit.
Lack of perceived social support from family and friends for the pregnancy. Oddly it's not always lack of support, it's the concept that you feel you have lack of support. Sometimes it is lack of emotional or financial support from the partner that is real, and that too can be worked through before planning pregnancy.
Living without a partner, now days there seem to be many viable partnerships that work, but being on one's own, having an unplanned or unwanted pregnancy does increase your risk for post partum depression. Planning can help make that pregnancy and post partum time successful.
Previous miscarriage also puts you at risk, working through how you felt will help you be at less risk for post partum depression.
A poor relationship with one's own mother, some relationships can be patched up!
Not breastfeeding, so at least try!
Unemployment in the mother (no job to return to) or in the head of household, again, not always avoidable, but perhaps land that job before planning pregnancy.
Pregestational or gestational diabetes, and diet and exercise can help you avoid this risk factor.
At Women's Health Practice we encourage patients to have a pregnancy planning visit.