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New Studies in Postpartum Depression

Kathleen Kendall-Tackett, PhD, IBCLC
Henniker NH USA
From: LEAVEN, Vol. 41 No. 4, August-September 2005, pp. 75-79.

In the past decade, there have been hundreds of new studies on postpartum depression. This research provides much-needed information to professionals and volunteers working with new mothers. In this article, Kathleen Kendall-Tackett summarizes some of the recent developments in this field, and highlights what these changes mean for breastfeeding mothers.

Depression and the Breastfeeding Mother

We've known for more than a decade that maternal depression can cause problems for babies and children. Infants of depressed mothers are at increased risk for abnormal brain activation patterns (documented via electroencephalograph), social difficulties, and even lowered IQ. Part of the reason these problems occur is because depression influences the way mothers interact with their infants. Researchers have identified two interaction styles of depressed mothers. They either disengage from their babies (avoidant style), or react in an intrusive or hostile way (angry/intrusive style). Either way, depression often limits a mother's ability to read her baby's cues and respond appropriately.

But here is the good news. In a 2004 study published in Biological Psychology, Jones and colleagues found that breastfeeding protected infants from the harmful effects of maternal depression. They compared four groups of infants: infants of depressed mothers who were either breast or bottle-feeding, and infants of non-depressed mothers who were either breast or bottle-feeding. The infants of depressed bottle-feeding mothers had abnormal brain activation patterns, such as those found in previous studies. But the infants of depressed breastfeeding mothers were no different than those of non-depressed mothers. One apparent reason for this finding is that by simply breastfeeding, mothers were more likely to touch, stroke, and make eye contact with their babies -- something we've all observed. This is one more good reason for encouraging mothers to continue to breastfeed even while depressed.

Depression and Breastfeeding Cessation

Depressed mothers are at high risk for quitting breastfeeding. Misri, Sinclair, and Kuan (2000), in their study of 51 postpartum women with major depression, reported that 83 percent of the women became depressed and then stopped breastfeeding. Only 17 percent reported that depression began after they stopped breastfeeding. Similarly, Bick and colleagues (1998) found that depression predicted early weaning in a study of 906 English women.

Nipple pain, a frequent reason why women quit breastfeeding, can also have a psychological impact on mothers. Amir et al. (1996) compared breastfeeding women with and without nipple pain. The women with pain were significantly more likely to be depressed, and had significantly higher scores on all mood factors on the Profile of Mood States (tension, depression, fatigue, confusion, and vigor). Once the pain resolved, the scores on these scales dropped to normal levels.

Postpartum Stress, Fatigue, and Depression

One positive trend in the literature is that it now includes more holistic models of depression that include both stress and fatigue. Stress and fatigue can increase risk for depression, but lowering stress can be protective. This is where breastfeeding can make a difference. Mezzacappa and Katkin (2002) compared maternal stress levels after both breast and bottle-feeding, with 28 mothers who were doing both. They measured stress immediately after breastfeeding, and immediately after these same mothers bottle-fed. The design of this study allowed the authors to account for pre-existing differences in mothers who chose to breastfeed rather than bottle feed since each mother was compared to herself. They found that the act of breastfeeding decreased mothers' negative moods, and when these same women bottle-fed, bottle-feeding decreased their positive mood.

As great as breastfeeding is for lowering stress, breastfeeding difficulties can increase both stress and depression. In a sample of 41 breastfeeding mothers, depression, stress, severity of breastfeeding problems, and fatigue were moderately correlated with each other. These measures were taken at three days, and three, six, and nine weeks postpartum (Wambach 1998).

Severe fatigue also predicts future depression. One recent study recruited 38 healthy new mothers who had uncomplicated births in the first day postpartum (Bozoky and Corwin 2002). The authors found that fatigue at day seven predicted depression at day 28. Indeed, fatigue on day seven accounted for 21 percent of the variance in depressive symptoms. Similarly, a study of 465 postpartum women also found that sleep problems at one month postpartum predicted depression at four months (Chaudron et al. 2001).

Stress Hormones and Breastfeeding

Stress can also upset the balance of neurotransmitters in the brain, increasing the risk of depression. According to Marshall (1993), high levels of stress alter the balance between the neurotransmitters acetylcholine and norepinephrine, resulting in too much acetylcholine. Too much acetylcholine leads to secretion of the stress hormone cortisol. Cortisol levels are often elevated in people who are depressed, and elevated cortisol levels can impact breastfeeding.

Grajeda and Perez-Escamilla (2002) measured the cortisol levels of 136 women from Guatemala before and after birth. They found that first-time mothers had higher cortisol levels overall, and cortisol levels were substantially elevated after birth. For women with the highest levels of cortisol, lactogenesis II (when milk becomes more plentiful) was delayed by several days.

More recently, Groër and colleagues (2005) examined the relationships between maternal fatigue, stress, and depression. They found that breastfeeding women with the highest cortisol levels were the most tired. They also found that mothers who were stressed, fatigued, or depressed had lower levels of prolactin in their milk and in their blood than mothers who were not tired and stressed. Lower prolactin levels may impact milk supply, which in turn may lead to breastfeeding cessation.

Exercise for Depressed People

Because of the overlap of stress, depression, and fatigue, some have considered exercise an excellent intervention because it addresses all three. Several recent studies have demonstrated the effectiveness of exercise in boosting mood and relieving stress. For example, in a large study from Finland (N=3,403), exercise lowered depression and helped with feelings of anger, distrust, and stress. Two to three times a week was enough to achieve this mood-altering effect (Hassmen et al. 2000).

Exercise can even be helpful for major depression (Babyak et al. 2000). In a study conducted at Duke University Medical Center (North Carolina, USA), subjects with major depression were randomly assigned to three groups: exercise alone; sertraline (Zoloft) alone; or a combination of exercise and sertraline. All subjects improved after four months, and there were no differences between the groups. In other words, people in the exercise-only group did as well as people in the two medication groups.

The mood-altering effects of exercise appear fairly quickly. In a study of 26 women, Lane and colleagues (2002) measured anger, confusion, depression, fatigue, tension, and vigor before and after two exercise sessions. There was significant mood enhancement after each exercise session. Depressed mood was especially sensitive to exercise, and decreased significantly after each session.

What Mothers Can Do

Exercise can be a helpful treatment for depression and can be used alone or in combination with other treatment modalities. To achieve an antidepressant effect, mothers should exercise two to three times a week for at least 20 minutes.

Depression, the Immune System, and Cytokine Activity

Another intriguing line of research has to do with the role of the immune system in the development of depression. Miller (1998) noted that cytokines, the chemical messengers of the white blood cells, such as interleukin-1 (IL-1), may be related to depression. When pro-inflammatory cytokines circulate in the system, they mediate sickness behavior in humans, including increasing fatigue. Cytokines also stimulate the release of cortisol.

Cytokines and Immune Markers in Postpartum Women

Physical stress can increase cytokine production. Not surprisingly, cytokine levels are often elevated in women after giving birth. One study found that postpartum women are generally higher in the cytokines IL-6, IL-6R, and IL-IRA than before delivery (Maes et al. 2000). Another recent study (Corwin et al. 2003) found that interleukin-1 (IL-1) was related to fatigue in postpartum women. Corwin et al. collected measures of fatigue and levels of IL-1 over four weeks postpartum. They found that IL-1 is elevated during the postpartum period, and that this elevation has a significant, though delayed, relationship to postpartum fatigue. IL-1 may have an indirect link to postpartum depression through fatigue.

These studies on the immune system are preliminary, but of interest. They give us one more way to understand depression in postpartum women. They also underscore the complexity and interrelationships between the biological pathways and depression. Immune system involvement can also help explain why some treatments for depression are effective -- particularly treatments that are anti-inflammatory, such as Omega-3 fatty acids.

Why Omega-3s May Influence Depression

There are a number of theories about why Omega-3s (particularly EPA and DHA) might have an influence on depression. One proposed mechanism relates to immune system function and the production of cytokines, particularly interleukin-1‚ (IL-1), IL-2, and IL-6 (Maes and Smith 1998). Cytokines are involved in depression in a variety of ways. First, they provoke symptoms identical to major depression in humans (e.g., lethargy, social withdrawal). Second, they activate the hypothalamic-pituitary-adrenal axis, raising cortisol levels. Third, IL-1 and IL-6 lower serum concentrations of tryptophan (the precursor to serotonin, the neurotransmitter that is often low in depressed people) and alter brain metabolism of serotonin. And fourth, antidepressants suppress cytokines, suggesting that these medications are also anti-inflammatory. Simopoulos (2002) noted that major depression and several physical illnesses (coronary heart disease, cancer, arthritis, Crohn's disease, ulcerative colitis, and lupus erythematosis) all feature high levels of IL-1. Omega-3s reduce cytokine production.

How to Get Omega-3s

Getting Omega-3s from food can ease depression. A population study from New Zealand found that fish consumption was related to higher self-reported mental health. This study controlled for possible confounds including age, household income, eating patterns, alcohol use, and smoking. The authors felt their findings provided indirect support for the relationship between omega-3s and mood stabilization (Silvers and Scott 2002).

There is, however, concern about mercury contamination in seafood as mercury can have a negative impact on the baby's developing nervous system. Because of contaminants, pregnant and lactating women may not be able to eat enough seafood to get an anti-depressant effect, as they may be limited to one or two servings a month. Fish oil supplements are an alternative way to receive Omega-3s (especially EPA and DHA). However, contaminants in supplements are also a real concern. The amount of contaminants in over-the-counter brands is often impossible to determine. The key is to use pharmaceutical-grade Omega-3s. These are available to consumers online or through naturopathic physicians.

Flaxseed is not a good alternative for an anti-depressant effect since the principal Omega-3 in flaxseed is alpha-linolenic acid (ALA). ALA is metabolically farther removed from EPA and DHA. Supplementation with ALA does not appear to increase EPA and DHA levels to sufficient levels, and appears to have no impact on depression (Bratman and Girman 2003). It does, however, have other beneficial effects on cardiovascular health.

Conditions That Are Co-Morbid with Postpartum Depression

Another positive trend in our understanding of postpartum depression is the inclusion of co-morbid conditions, or conditions that co-occur with depression. There are several conditions that can occur along with postpartum depression including postpartum obsessive compulsive disorder, posttraumatic stress disorder, eating disorders, substance abuse, and bipolar disorder. These are briefly described below. These co-occurring conditions can be difficult to identify and tease apart from depression, and is not something that Leaders should attempt. But you should know that treatment is more complex with regard to breastfeeding as these conditions may require additional medications such as anti-convulsants and adrenergic agents. Most of these additional medications are compatible with breastfeeding, but in every category, some choices are better than others. (For a complete description of treatments for these conditions and how they impact breastfeeding, see Depression in New Mothers.)

Obsessive Compulsive Disorder

Obsessive compulsive disorder (OCD) is an anxiety disorder characterized by recurrent, unwelcome thoughts, ideas, or doubts that give rise to anxiety and distress. The exact incidence of postpartum OCD is not known, but the birth of a child, particularly with high rates of obstetric complications, is one of the known triggers of symptoms (Maina et al. 1999).

In postpartum women, obsessional thoughts are often focused on infant harm such as fears of harming the baby with knives, throwing the baby down stairs or out a window (Abramowitz et al. 2002). Other types of obsessions concerned repetitive thoughts of their babies dying in their sleep, or that they would sexually misuse their babies, or physically misplace them.

Beck (2002) identified anxiety, relentless obsessive thinking, anger, guilt, and contemplating self-harm as part of her "spiraling down" dimension of postpartum depression. Women in her study tended to ruminate over feelings of failure as mothers, fearing that they or their babies might be harmed, wondering if they would ever feel normal again, and constantly worrying about the baby. These mothers tended to self-silence and isolate themselves because they were sure no one would understand what they were going through.

Posttraumatic Stress Disorder

Another co-occurring anxiety disorder is posttraumatic stress disorder (PTSD). Women may come into the postpartum period with pre-existing vulnerability to PTSD. PTSD could be due to prior trauma, such as previous abuse or sexual assault, or could be caused by their birth experiences. In a study of Vietnamese and Hmong women, Foss (2001) found that posttraumatic stress disorder was highly correlated with depression in this sample. And in reviewing previous studies on PTSD related to birth, Beck (2004) noted that one-and-a-half percent to six percent of women met full diagnostic criteria for PTSD. Even if women do not meet full criteria for PTSD, they may have troubling symptoms such as intrusive thoughts and sleep disturbances.

Eating Disorders

Eating disorders can also co-occur with depression during pregnancy and the postpartum period. In a sample of 49 women with eating disorders who had recently given birth, the rate of postpartum depression was 35 percent (Franko et al. 2001). Another study of 181 women found that binge eating and vomiting before pregnancy predicted postpartum depression. In addition, mothers whose eating disorders were active during pregnancy, particularly those with a binge and purge type of eating disorder, were the most distressed postpartum. However, low-intensity exercise alleviated some of their symptoms (Abraham, Taylor, and Conti 2001).

Substance Abuse

Substance abuse can also co-occur with postpartum depression. Two studies have considered the link between substance abuse and depression in mothers. In the first study of 391 pregnant women, substance abuse and life stress both predicted depression in pregnancy, as did difficulties with their friends, partners, and the women's own mothers (Pajulo et al. 2001a). A second study (Pajulo et al. 2001b) compared 12 mothers who abused substances, and 12 women who did not abuse substances (the control group) at three and six months postpartum. Not surprisingly, the substance-abusing mothers were significantly more depressed, had less social support, and more life stress than the control mothers. Their interactions with their babies were also less positive.

Substance abuse is obviously a serious problem for both mothers and babies. If women abuse substances during pregnancy, state authorities may intervene and remove the baby from the mother's care after delivery. For substance-abusing mothers, intervention for depression alone would be incomplete; they also need referrals to programs that can address their substance abuse.

Bipolar Disorder

Bipolar disorder, with or without psychosis, can also occur in the postpartum period. It is often overlooked because it usually manifests in the postpartum period as major depression without psychosis. In a study of 30 bipolar women who had children, 66 percent had a postpartum mood episode of some type (Freeman et al. 2002). Most often, these women were depressed. Of the women who became depressed after their first child, all became depressed after subsequent births. Depression during any pregnancy also increased the risk of postpartum depression.

Birth can also trigger episodes of psychosis in bipolar women with a family history of postpartum psychosis (Jones and Craddock 2001). One study examined 313 deliveries of 152 women with bipolar disorder. Twenty-six percent of the deliveries were followed by an episode of postpartum psychosis, and 38 percent of the women had at least one puerperal psychotic episode. Family history also increased risk. There were 27 women with bipolar disorder who had a family history of postpartum psychosis. Seventy-four percent of these women developed postpartum psychosis. In contrast, only 30 percent of the women with bipolar disorder, but without a family history of postpartum psychosis, had a postpartum psychotic episode.

Women with bipolar disorder are often undiagnosed until after they have children (Freeman et al. 2002). However, they pose a treatment challenge. Since their illness often manifests as major depression in the postpartum period, they may be treated with selective serotonin reuptake inhibitors (SSRIs). Unfortunately, in women with bipolar disorder, these medications can also trigger manic or rapid-cycling episodes. For these women, the anti-convulsant medications (such as Depakote) may be more appropriate in that they have both mood-stabilizing and antidepressant effects (Leibenluft 2000).

Conclusion

Recent research on depression in new mothers has provided us with more sophisticated models of understanding this complex condition. As Leaders, we need to be alert to both stress and fatigue in mothers as these are often precursors to depression, and encourage mothers to talk with their health care providers. We also know that breastfeeding can protect infants of depressed mothers from the harmful effects of maternal depression, and so we should encourage depressed mothers to continue to breastfeed whenever possible. We should also address breastfeeding difficulties, particularly pain, promptly, as these can increase maternal stress and depression. Finally, this new research indicates that while breastfeeding does not eliminate the risk of depression, it does lower the risk and can help ease mothers' transition to motherhood.

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Kathleen Kendall-Tackett, PhD, IBCLC, is a health psychologist, lactation consultant, and La Leche League Leader. She is Research Associate Professor of Psychology at the Family Research Lab, University of New Hampshire and chairs the New Hampshire Breastfeeding Task Force. She is the author or editor of 12 books on various aspects of women's health including the newly released, Depression in New Mothers, The Handbook of Women, Trauma and Stress, and The Hidden Feelings of Motherhood. She lives in New Hampshire, USA with her husband, Doug, and sons, Ken (15) and Chris (13). Kathleen currently serves on the LLLI Board of Directors. More information about depression can be found on her Web site at www.GraniteScientific.com.

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