CRH and progressive pseudorheumatoid arthropathy of childhood: A recent study shows that genetically predicted levels of C-reactive protein (CRP) are associated with PPD,51 supporting a previous finding that CRP levels before or immediately during the postpartum period predict PPD.57 A systematic review, however, shows that evidence for such biological theories is inconsistent.58 Although some studies suggest a role for corticotropin-releasing hormone trajectories during pregnancy,59,60 most studies have small samples, are inconsistent in their definition of PPD and do not account for environmental confounders.