Up to a quarter of women in low- and middle-income countries experience depression during pregnancy, and an estimated one-fifth experience postpartum depression, based on current estimates. Those rates exceed the estimated prevalence in high-income countries of 7% to 15% for prenatal depression and 10% for postpartum depression.
Although postpartum depression has historically gotten the most attention, both postpartum and prenatal depression are among the most significant contributors to maternal morbidity and mortality. And yet, researchers understand far too little about perinatal depression, particularly outside of high-income countries, noted the investigators in a recent review of the literature on this topic.
“Despite its enormous burden, maternal depression in low-income and middle-income countries remains under-recognized and undertreated,” wrote Bizu Gelaye, PhD, of the Harvard T. H. Chan School of Public Health in Boston, Massachusetts, and colleagues in Lancet Psychiatry.
The etiology of perinatal depression likewise is not fully understood, although risk factors such as financial and socio-environmental distress increase the likelihood of it.
“Some investigators have speculated that pregnancy related hormonal changes might increase vulnerability for the onset or return of depression,” the researchers wrote. “For example, blunted memory and diminished anxiety during pregnancy have been associated with progesterone and glucocorticoids.” But most of these speculations remain hypotheses without extensive reliable evidence.
Reviewing the Literature
To characterize what is known in the literature, the researchers conducted a search of studies on the prevalence of perinatal depression, occurring either prenatally or postpartum, in low- and middle-income countries. Their final selection included 51 papers on prenatal depression and 53 on postpartum depression. They then conducted a similar search for studies investigating associations between perinatal depression and infant and child outcomes. They identified 25 studies, including 5 focused on prenatal depression and 20 on postpartum depression.
Though the Edinburgh Postnatal Depression Scale was by far the most commonly used tool, various other instruments were used to screen or diagnose maternal depression in the studies in the review:
- Structured Clinical Interview for DSM-IV (SCID)
- Edinburgh Postnatal Depression Scale (EPDS)
- Patient Health Questionnaire-9 (PHQ-9)
- Mini International Neuropsychiatric Interview (MINI)
- Hamilton Depression Scale
- Beck Depression Inventory (BDI)
- Aga Khan University Anxiety and Depression Scale
- Composite International Diagnostic Interview
- Johns Hopkins Symptom Checklist
- Primary Care Evaluation of Mental Disorders
- Self-Rating Depression Scale
- Self-Reporting Questionnaire
Prevalence of Perinatal Depression
Based on a population of nearly 49,000 women in the 51 studies on prenatal depression, prevalence of the condition was 25%. The studies were quite heterogeneous, however, and publication bias was evident in several of the studies. Even after conducting a sensitivity analysis, however, the prevalence only edged up 1 point to 26%.
Brazil was the country most represented in the studies, accounting for 15 of them, and 6 were from Turkey. Other studies came from South Africa, China, Pakistan, and a handful of countries primarily in southeast Asia or Africa, plus Mexico, Jamaica, and Peru.
The 53 studies on postpartum depression, involving more than 38,000 women, had a pooled prevalence of 20% for postpartum depression. Despite similar heterogeneity among these studies, no publication bias was evident. This group also included more studies from Brazil and Turkey than elsewhere. Four studies each came from India, Thailand and China, and 3 each from Mexico, Nigeria, and Iran. Others were mostly from the Middle East, Central Asia, Southeast Asia, and Africa.
“The high prevalence of perinatal depression is influenced by a number of risk factors, including increased somatic symptoms, exposure to intimate partner violence, lack of social support, unintended pregnancy and high rates of relapse of depression during the perinatal period,” the investigators wrote. “Antepartum [prenatal] depression has been linked to negative health-related behaviors and adverse outcomes, including poor nutrition, increased substance use, inadequate prenatal care, preeclampsia, low birth weight, preterm delivery, postpartum depression, and suicide.”
Identification of Risk Factors
Evidence on potential links between childhood abuse and perinatal depression is sparse, but a handful of studies have found an approximately 2.5-fold increase in odds in women with a history of sexual and/or physical abuse, even after accounting for other risk factors.
“Biological mechanisms underlying reported associations of child abuse with perinatal depression are thought to be related to disruptions of neurobiological stress response systems including the sympathetic nervous system, the serotonin system, and the hypothalamic-pituitary-adrenal axis,” the investigators wrote.
Intimate partner violence, which has a prevalence rate ranging from 10% to 52% globally, often involves psychological and sexual abuse as well, and has an even greater impact on the prevalence of perinatal depression. Studies found the odds of perinatal depression were 4 to 6 times greater in mothers who have experienced intimate partner violence.
The studies identified additional risk factors in low- and middle-income countries as “maternal low educational attainment, low socioeconomic status at the time of pregnancy, lack of social support and history of mental illness.” In fact, low education levels increased odds of postpartum depression more than 5-fold.