“According to Prof. Strous, one of the most influential factors [as to whether a woman would develop PTSD was pain management during delivery. Of the women who experienced partial or full post-trauma symptoms, 80 percent had gone through a natural childbirth, without any form of pain relief. ‘The less pain relief there was, the higher the woman’s chances of developing post-partum PTSD,’ he said. Of the women who did not develop any PTSD symptoms, only 48 percent experienced a natural childbirth.” https://www.sciencedaily.com/releases/2012/08/120808121949.htm.
A study of the risk of psychological complications with prolonged physical pain after childbirth also uncovered a possible correlation between postpartum depression and the duration of pain after childbirth: “Presenting recently at the World Congress of Anaesthesiologists in Hong Kong, the team from Duke-NUS Medical School described their followup on 138 healthy women who received an epidural while delivering their first baby. The new mothers reported their pain levels in the weeks after childbirth; meanwhile, readings on the Edinburgh Postnatal Depression Scale (EPDS) signaled which women were suffering from the condition. With EPDS scores of 12 or higher, the investigators determined that 5.8% of the new moms had in fact developed postpartum depression by week 4 or later. The women with the highest scores were those who also reported being in pain for longer than 4 weeks, and the lowest scores were for mothers who experienced no pain at all following childbirth. ‘The research findings support the need to address pain comprehensively to lessen the risk of developing PND [postnatal depression], and a larger study is being conducted to evaluate the impact of pain and PND in pregnant women,’ remarked medical student and study coauthor Wei Du.” http://www.pharmacist.com/childbirth-pain-linked-risk-postpartum-depression
“New mothers who reported higher stress levels, greater pain vulnerability during labor or delivery, and greater anxiety at 6-8 weeks after childbirth also had higher [risk of postpartum depression], the researchers report… The research findings support the need to address pain comprehensively to lessen the risk of developing PND [postnatal depression], and a larger study is being conducted to evaluate the impact of pain and PND in pregnant women.”