I've looked into birthing classes and the subjects they teach and the only real value I see in them is meeting other parents going through the same thing. (health-and-parenting.com)
For a fuller discussion of higher and lower heating values see heat content. (eia.gov)
From feelings of depression, anger, and sadness to frustration with their own self value we see that this can be harmful and even lead to shame. (shameproofparenting.com)