"Randomized controlled trial to prevent postpartum depression in adolescent mothers"
AJOG Mar 2013
http://www.ajog.org/article/S0002-9378(13)00003-3/fulltext 
"Results

Participants included Hispanic (53%), non-Hispanic black (17%), and non-Hispanic white (16%) adolescents. The overall rate of depression in the intervention group (12.5%) was lower than the control group (25%) with a hazard rate ratio of 0.44 (95% confidence interval, 0.17−1.15) at 6 months after delivery.

Conclusion

An intervention that is delivered during the prenatal period has the potential to reduce the risk for postpartum depression in primiparous adolescent mothers."