Last season, and now this one, Black-Ish has carved out a path, for a TV sitcom, that I believe to be unprecedented. In last year’s finale, to cap off what seemed to be a routine story line about a character’s pregnancy and delivery, Bow (Tracee Ellis Ross) had to endure some unexpected complications: Her baby had preeclampsia, and was delivered by emergency C-section – eight weeks premature. And tonight, with the baby and mother safely home, the complications, and the drama, continue, because Bow is showing clear signs of suffering from a condition that’s not that uncommon, but seldom discussed, especially on television: postpartum depression.