PPD occurs in approximately 10% to 20% of new mothers [3,5,93,132]. According to multiple studies, PPD occurs at the same rate in new mothers around the world [6]. There is little evidence to suggest that any country or class of persons is not at risk for PPD. Symptoms usually occur shortly after childbirth but may occur as late as one year after delivery. PPD is a serious, long-lasting type of depression in women that can have harmful consequences for the mother and child if undetected and untreated [3].

Documentation of PPD can be traced to the writings of Hippocrates in the fourth century B.C.E. Hippocrates described melancholia as a state of "aversion to food, despondency, sleeplessness, irritability, and restlessness" [6]. Galen (131–201 C.E.) described melancholia as "fear and depression, discontent with life, and hatred of all people" [6]. Greco-Roman medicine recognized melancholia in the form of fear, suspicion, aggression, and suicidal thoughts. In 1436, the life story of a young mother was published and described how she felt "insane" and despaired of her life and survival after the birth of her first child [11].

Although PPD occurs worldwide, cultural differences can influence the perception of depression in women. Culture influences the expression and interpretation of symptoms, the definition of stressors, the nature of the social support system, and the relationship between healthcare provider and patient. Culture also dictates whether certain expressions of symptoms are socially acceptable. An individual's view of illness and health is also culturally bound. Displays of emotion may be encouraged in some cultures and discouraged in others [27].

PPD affects women of all ages, economic statuses, and racial/ethnic backgrounds. Any woman who is pregnant or has given birth can develop PPD. Whether the birth is a first child or one of multiple births has not been shown to affect the incidence of PPD. However, women with a history of depressive episodes have a greater risk for developing PPD than women with no prior history of depression. The risk of PPD is highest in women younger than 25 years of age with a prior history of mood instability. Among these women, it is estimated that 30% to 40% will have a postpartum episode of depression [30,70]. There are additional risk factors evident prior to pregnancy that may increase the chances of developing PPD, including [5,30,70]:

Treating depression during pregnancy is a challenge because the vast majority of antidepressants cross the placenta and can have negative effects on fetal development. Psychiatrists, family practice physicians, and obstetricians may find themselves in a dilemma when diagnosing and treating depression in pregnant patients. As previously noted, the onset of depression may not become evident until symptoms become severe due to the similarity of depressive symptoms and neurovegetative signs during pregnancy [33]. Although diagnosis and treatment pose a serious challenge, early recognition, diagnosis, and treatment are warranted [33]. Indication of certain risk factors that may contribute to depression during pregnancy can be helpful in a prenatal assessment. Risk factors for an onset of depression during pregnancy include [5,33,70]:

Risk factors for PPD following the birth of a baby are similar to those present prior to conception and during pregnancy. Any combination of the following factors should be considered concerning, as it indicates a potential to develop PPD [5,34,70]:

The areas of the brain affected by female reproductive hormones (i.e., estrogen and progesterone) are the same as those known to regulate mood stability and behavior. Therefore, it may be concluded that different hormonal circumstances can alter mood and anxiety in a woman [13]. There are several events associated with a woman's reproductive cycle that provoke mood instability in predisposed individuals, including the use of oral contraceptives, phases of the menstrual cycle, pregnancy and the postpartum period, and menopause. The vulnerability of women for mood instability bears some relationship to the fluctuation of ovarian steroids during specific phases of the reproductive cycle [36,37].

Every significant event in life is accompanied by emotions. These events are thus emotional experiences that are "recorded" in the brain. The "emotional brain" is thought to consist of the prefrontal cortex, which is the area located directly above the eyes, and the frontal cortex. The prefrontal cortex is significantly involved with developing judgment [13]. Sichel and Driscoll refer to the connections between the limbic brain, the paralimbic brain, and the prefrontal cortex as the "prefrontal limbic complex" [13]. This complex has a large role in processing emotions, regulating mood, and storing memories. The memories of powerful life experiences, both stressful and pleasurable, are stored in this area of the brain.

Serotonin is a neurotransmitter known to be involved in mood and anxiety disorders. It is one of the major classes of chemical messengers known as monoamines and is associated with the induction of emotional calmness and the perception and regulation of pain, restful sleep, sexual behavior, and appetite control. A person's general level of well-being depends largely on his or her levels of serotonin [19].

Progesterone is produced during the second phase of the menstrual cycle and functions to dismantle the nerve connections established by estrogen, decreasing the number of available estrogen receptors [13]. Like estrogen, progesterone is also available in large quantities during pregnancy and drops significantly after childbirth.

Approximately 5% to 7% of postpartum women have abnormal thyroid levels [55,56]. Thyroid dysfunction is associated with depressed mood, and in one study, having a thyroid-stimulating hormone (TSH) level greater than 4.0 mU/L at delivery was associated with increased risk for depressive symptoms at six months postpartum [42,57,58,59]. Thyroid dysfunction has not been consistently identified in PPD; however, there may be a subgroup for whom it does play a role.

With this in mind, certain traits are possible indicators of disturbances in brain chemistry and mood instability in some individuals [30]. Some important traits that may become evident when taking a patient's history include:

The brain's mood pathways can presumably be restored to normal following one depressive event without any further episodes, assuming that the depression is treated aggressively and appropriately. However, research has shown that 70% of those who become depressed will have another depressive episode [13,62].

Postpartum blues, also referred to as "baby blues," is the most common type of postpartum mood disturbance, occurring in approximately 70% to 85% of all new mothers [3,70,132]. Its onset is usually shortly after birth, and it generally resolves within 10 days [2,3]. A study by Iles et al. indicated a characteristic pattern of mood changes that peaked on day 5 after delivery and declined by day 10, perhaps best described as a period of emotional upheaval following birth [71]. Incessant crying and tearfulness are the most common emotional expressions of postpartum blues [2,3].

Postpartum blues, also referred to as "baby blues," is the most common type of postpartum mood disturbance, occurring in approximately 70% to 85% of all new mothers [3,70,132]. Its onset is usually shortly after birth, and it generally resolves within 10 days [2,3]. A study by Iles et al. indicated a characteristic pattern of mood changes that peaked on day 5 after delivery and declined by day 10, perhaps best described as a period of emotional upheaval following birth [71]. Incessant crying and tearfulness are the most common emotional expressions of postpartum blues [2,3].

With an annual live birth rate of nearly 3.7 million in the United States each year, an estimated 555,000 women experience PPD in the United States [79]. Women who miscarry or whose children are stillborn are also susceptible to PPD. When this group is included in the figures, an estimated 830,000 women suffer from PPD each year [51,80]. Several studies have shown that PPD occurs with greater frequency in the first 3 months following childbirth than in the 6 or 12 months following [81]. Although exact percentages vary, it has been reported that between 40% to 90% of PPD cases occur within three months after childbirth. Nonetheless, women should be carefully assessed throughout the first year after childbirth, as PPD can occur up to one year postpartum [66,70].

When PPD affects cognitive abilities, it may present as [2,3,10,82]:

All new mothers experience a change in sleep patterns. Due to the baby's presence and the need for feedings during the night, most new mothers suffer from some degree of sleep deprivation. There is a different quality to sleep problems in women with PPD. These women have difficulty getting to sleep, have disturbed sleep, and/or wake early and are unable to go back to sleep. Insomnia is a common complaint. Even when they do sleep, it is never enough; the sleep is not refreshing. Five hours of solid sleep is often recommended; however, women with PPD are rarely able to sleep for that length of time. It is usual for new mothers to have their sleep interrupted by a crying baby, but women with PPD report that they cannot go to sleep even when the baby is settled and goes to sleep. They may lie awake worrying. Although rare, some women with PPD report sleeping too much [2,82].

Postpartum psychosis is an extreme condition that can occur during the postpartum period. The term "psychosis" is defined as a mental state characterized by being out of touch with reality [2]. Postpartum psychosis affects approximately 1 or 2 in 1,000 first-time mothers [3,15]. For women who experience psychosis after the birth of their first child, the risk increases by 50% for subsequent deliveries [15]. The major risk factors for postpartum psychosis are a personal history of PPD or psychosis, a family history of depression, or the presence of bipolar disorder [3,15,43,69]. One study found that nearly 10% of women hospitalized for psychiatric conditions before delivery went on to develop postpartum psychosis after their first child was born [83]. When it does occur, psychosis in a new mother constitutes a psychiatric emergency, requiring immediate treatment and, in many cases, psychiatric hospitalization.

Postpartum psychosis is characterized by hallucinations, delusions, confusion, extreme agitation, inability to carry on a coherent conversation, and inability to sleep or eat [3,69]. Moods may swing from euphoria to homicidal or suicidal ideation in a short period of time without warning. The risk of suicide or infanticide requires immediate attention. Safeguards should be established to protect the mother from harming herself or her baby until psychiatric intervention becomes available [13]. Irrationality is the hallmark of postpartum psychosis, and a mother's behavior may be peculiar or described as bizarre. She may engage in frenzied activities, as though in response to stimuli not apparent to anyone other than herself [10].

Data from the Centers for Disease Control and Prevention (CDC) and other studies indicate that 10% to 20% of new mothers suffer from PPD, and up to 85% experience postpartum blues [92,93,94,95]. A 2017 study found a decline in PPD from 14.8% in 2004 to 9.8% in 2012 [230]. The rate of depressive disorders diagnosed at the time of delivery increased from 4.1 per 1,000 hospitalizations in 2000 to 28.7 per 1,000 hospitalizations in 2015 [231]. The CDC has therefore recommended that healthcare providers address the issue of PPD during prenatal visits, preferably during the third trimester [92]. Other sources, including the U.S. Preventive Services Task Force (USPSTF), recommend assessing for depression throughout the prenatal period [94,96]. The USPSTF has stated that screening pregnant and postpartum women for depression may reduce depressive symptoms in women and that screening instruments can identify pregnant and postpartum women who need further evaluation and who may need treatment [94]. The screening should be implemented with adequate systems in place to ensure accurate diagnosis, effective treatment, and appropriate follow-up [94,97].

The EPDS is limited to certain depressive symptoms and does not evaluate a woman's exhaustion, irrational irritability, or thoughts of harming her baby. These symptoms should be examined during a clinical assessment by asking specific questions relevant to these areas. Nonetheless, the EPDS is the most widely used screening tool available to detect PPD [10]. Given prenatally, the EPDS has been shown to effectively identify women at risk for PPD [102]. The EPDS may be accessed online at http://www.fresno.ucsf.edu/pediatrics/downloads/edinburghscale.pdf.

The test yields an overall severity score falling into three ranges:

Bonding, in actuality, is a process of closeness, comfort, and familiarity that develops over time [19]. When the process of bonding with an infant is disrupted, it can have long-term consequences for the future relationship between mother and child. The delay in developing attachment may be unusually prolonged and delayed with a clinically depressed mother. This attachment difficulty may take different forms. The mother may not be nurturing to the infant, or she may have limited interaction with the infant. In some cases, the depressed mother may reject her baby emotionally and refuse to have anything to do with the infant. The mother may have an adverse sentiment towards the baby and handle the baby with irritability. Depressed mothers may also be outwardly angry or resentful toward the infant. Some mothers are so consumed with fears of harming their child that they avoid even touching him or her. All of these emotions and attitudes toward the child affect the process of attachment [2,109].

Klier and Muzik describe the role of perinatal psychiatry in maternal-infant bonding issues [110]. They classify the disorders of mother-infant bonding into three groups [110]:

Researchers of infant behavior have come to acknowledge that the establishment of social relationships is a primary process of development. When a child successfully accomplishes communication with others, normal development occurs. A child who does not engage the world successfully will not develop normally, regardless of the source of the failure. Success or failure depends upon three critical processes [112]:

Studies have shown that when the mother is depressed, a break in the mutual regulatory system occurs [114]. Depressed mothers disrupt the interaction in two distinct ways: intrusiveness and withdrawal. It has been reported that intrusive mothers with PPD engaged in rough handling, spoke in an angry tone of voice, and interfered with their infants' activities. Withdrawn mothers, by contrast, were disengaged, unresponsive, and affectively flat and did little to support their infants' activities.

A study has been completed assessing the long-term effects on the children of mothers who were depressed three months postpartum [126]. In a community sample from two general practices in London, 149 women were given psychiatric interviews at three months after childbirth, and 89% of their children were assessed at 11 years of age. The children of women who were depressed at three months postpartum suffered attention deficit problems, difficulty with mathematics, and were more likely than other children to have special educational needs. The cognitive deficits present at 11 years of age may be a result of the quality of the infant's social environment in the first three months of life. Problems were noted in the children whether or not the mothers' depression continued beyond three months. Boys were more severely affected than girls. These effects on cognitive development were not altered by the parent's intelligence quotient (IQ) or socioeconomic status, or by the mother's later mental health problems. In this study, PPD was a risk factor for children's subsequent cognitive and behavioral problems. These findings demonstrate a long-term legacy of PPD that continues to affect children's intellectual development into adolescence [126]. Subsequent studies have reported similar findings [127,128,129].

Statistics show that psychiatric disorders, and specifically suicide, account for 20% to 30% of all maternal deaths [93,130]. A study of Danish women published in 2016 indicated that unnatural maternal causes of death (e.g., suicides, accidents, homicides) accounted for 40.6% of fatalities among women with identified psychiatric illness within one year of childbirth [131]. In the United States, suicide is considered the greatest cause of maternal mortality in the year following childbirth [93,130].

If possible, a spouse or other caregiving partner can alternate nights getting up to take care of the baby, allowing the mother to sleep at least five hours at a time. Knowing in advance that arrangements for nighttime feedings and attention to the baby can be made, mothers may ask for help without feelings of guilt or inadequacy [5]. Because women with PPD often complain of insomnia, a safe sedative may be prescribed to allow patients to obtain enough sleep.

There is some evidence that men may experience a form of PPD following the birth of their child [151,152]. The strongest predictor of paternal PPD in one study was the presence of maternal depression, with symptoms tending to arise after those of the mother [152]. Therefore, fathers should also be assessed for signs and symptoms of depression in the postpartum period, particularly when their partner is depressed. Educating both parents can assist them to work together for mutual benefit and for the benefit of the baby, and may alleviate possible marital discord. In one analysis, fathers reported fewer depressive symptoms if they received support from midwives, child health nurses, and their partners (mothers) [194].

One problem with the use of progesterone is that it cannot be given successfully by mouth or as a skin patch but must be administered by injection or vaginal or rectal suppository. According to Dalton and Horton, 400-mg suppositories administered twice daily are the minimum effective dose [10]. However, empirical data has not found progesterone to be effective in the treatment of PPD and it may intensify depressive symptoms in some patients [157].

The U.S. Food and Drug Administration (FDA) has alerted healthcare professionals and the public regarding a potentially life-threatening condition called serotonin syndrome. Serotonin syndrome, or serotonin toxicity, results from an excess of serotonergic activity in the central nervous system. It is seen only rarely in postpartum women, usually when multiple antidepressants, such as TCAs, MAOIs, St. John's wort, or opioids are combined. Serotonin syndrome is a medical emergency that requires immediate treatment. Symptoms and signs of this syndrome include [167,168]:

Studies have shown that SSRIs peak in the breast milk seven to nine hours after maternal dosing. The highest concentrations are found in the hindmilk [163,176,232]. The best time to nurse is one hour before taking the SSRIs. If a mother must breastfeed during the peak concentration, she may nurse for a brief period and discard the hindmilk, which will help to reduce the amount of medication the baby receives [177].

Fluoxetine produces the highest proportion of infant levels (22%), elevated more than 10% above the average maternal level, and fluoxetine has a longer half-life than either sertraline or paroxetine [166]. Two case reports of nursing infants whose mothers were taking fluoxetine related instances of increased irritability, colic, increased crying, decreased sleep, increased vomiting, and watery stools [176]. The long-term neurobehavioral development of infants exposed to fluoxetine has not been investigated. It is a drug "of concern" and should be used with caution in nursing mothers [163].

There are a variety of factors that contraindicate the use of TCAs. TCAs should not be prescribed to anyone with a history of heart disease, as they may cause cardiovascular problems. There have also been cases of TCAs triggering manic episodes in patients with a personal or family history of bipolar disorder [190,191]. It is also important not to prescribe TCAs with any of the following medications or other items, as there are risks of dangerous interactions [189]:

The advantages of group therapy are that it is cost effective, reduces isolation, and offers support and empathy from others with similar problems. The disadvantages are that there is no one-on-one interaction between the therapist and each individual, and the group is not specifically tailored to meet each individual's particular needs [34]. Additionally, some mothers' childcare responsibilities may interfere with their ability to attend and participate in group therapy sessions [199]. A feasibility study on the effects of telecare therapy (i.e., a combination of cognitive-behavioral therapy, relaxation techniques, and problem-solving strategies) indicated that this may be an effective treatment option for women with PPD who are unable to attend group therapy sessions or support groups [200].

Prevention of PPD is of utmost interest to researchers and clinicians, and it is clear that preventing severe depression would have clear benefits for mothers and children. Two barriers to effective and efficient postpartum care in the United States have been identified: the lack of parity between insurance coverage for mental and physical illnesses decreases access to care, and the current model of postpartum care fails to incorporate screening and follow-up. In developing a prevention model in the United States, these concerns should be taken into account. The types of prevention strategies employed should be determined by the risk factors with which a woman presents. Early detection and treatment are keys to a full recovery [207]. Healthcare professionals involved in childbirth education are in an excellent position to offer pregnant patients anticipatory information about postpartum complications, including PPD [124].

An effort to place greater emphasis on identifying any previous psychiatric illness in pregnant patients and their families, combined with the continuous observation of the psychologic well-being of women during pregnancy, will enable potential sufferers of PPD to receive treatment at the earliest possible stage. In addition to screening for PPD during pregnancy, screening at six weeks, three months, and six months postpartum should become routine. It remains the primary responsibility of physicians treating women of childbearing age to ensure that all healthcare professionals involved in prenatal care have a full knowledge of the devastating effects of PPD and actively work to detect women at risk as early as possible [10]. As noted, the EPDS is the most accepted and widely used screening tool available today and takes only a few minutes to administer. Having a standardized mechanism of screening available for all pregnant patients should become the standard of care. Without a formal assessment, most depressive symptoms will remain undetected by primary care health professionals [201].

If utilized, it is advised that, upon completion of labor, the patient is given 100 mg of progesterone by injection daily for seven days, followed by a 400 mg suppository twice daily until the return of menstruation. The dosage of suppositories may be increased if the mother experiences a return of mild early symptoms. Each woman should also be equipped with information about the symptoms of PPD [10]. At the end of two months, if menstruation has not begun and no symptoms appear, the number of suppositories may be reduced and then discontinued. If menstruation has begun and symptoms appear, progesterone should be given from day 14 of the cycle until the next menstruation. Natural progesterone should only be given in the prescribed method of administration. Studies have been conducted on progesterone preventive treatment in 1985, 1989, 1994, and 1995 [10]. In these studies, the prevention of symptom recurrence was 90% to 92% successful.