The findings also suggest that among mothers followed for a year after giving birth, close to 22 percent had been depressed. The authors recommend all pregnant women and new moms be screened for depression.
The current study is the largest scale depression screening of postpartum women and the first time a full psychiatric evaluation has been conducted in a study of postpartum women who were positively diagnosed with depression.
Northwestern Medicine lead study author Katherine L. Wisner, M.D. explained:
"In the U.S., the vast majority of postpartum women with depression are not identified or treated even though they are at higher risk for psychiatric disorders. It's a huge public health problem. A woman's mental health has a profound effect on fetal development as well as her child's physical and emotional development."
The researchers screened 10,000 mothers and found positive diagnoses in 1,396 women (14 percent). Of those, 826 (59.2 percent) completed the home visits and 147 (10.5 percent) completed telephone interviews.
Key findings from these evaluations included:
- Among women who screened positive for depression, 19.3 percent considered hurting themselves.
- Several women who screened positive for major depression postpartum had previously experienced depression in their lives and also had an anxiety disorder. Results showed 30 percent of women had depression before pregnancy, 40 percent postpartum, 30 percent while pregnant, and of these women two-thirds also had an anxiety disorder.
- There is often a delay in accurately diagnosing bipolar disorder - which requires symptoms of the depressed and manic phases. Postpartum is the greatest risk period for new episodes of mania in women.
Wisner said, "Depression during pregnancy increases the risk to a woman and her fetus. Depression is a physiological dysregulation disorder of the entire body."
Prenatal motherly stress and depression are linked to low infant birth weight and preterm birth - which increases the risk of cardiovascular disease. When a new mother is depressed her moods can affect child development and raise the rate of insecure attachment and declined cognitive performance in her child.
The authors emphasize that prenatal and postpartum screening are crucial, however, the healthcare field must develop inexpensive and readily available treatment.
"Although centralized depression screening by telephone as in this study is feasible in the early postpartum period, the challenge is to design a therapeutic program to support and retain women through diagnostic evaluation and treatment to maternal recovery and optimal function."
A previous study completed just a week ago, reported that women who receive strong social support from their families during pregnancy are less likely to develop a certain stress hormone, making them less likely to develop postpartum depression.