Things You Probably Don't Know About Postpartum Depression: Breastfeeding and The Influence of Hormones

Monday, August 18, 2014 by Meg   •   Filed under Postpartum Depression

Postpartum depression is an evolutionarily relevant hormonal response to stress that may be triggered by a lack of support or other environmental conditions. (Read more here in: PPD, Maternal Investment Theory and the Drive to Abandon and PPD, Spousal Support and the Benefit of Sister Wives. ) 

But breastfeeding may be an additional piece to the postnatal depression puzzle. 

Let me be clear: this is not a post about encouraging women to breastfeed as opposed to bottle feed. This is not a post shaming mothers for whatever choices they have made in the feeding realm. Every mother does what she feels is right for her and her child. 

This post is about us. Because maternal emotional regulation might be affected by breastfeeding, and the cessation of breastfeeding may be able to trigger mental health issues, including postpartum depression. Education matters so that women can understand the process and make the best choice for themselves and their families, whatever that choice happens to be.

So let's get into it. 

PPD and Mental Health Research

There is a mountain of research that shows a significant link between postpartum depression and lack of breastfeeding1,2. In previous studies, anxiety and depression were thought to lead to early breastfeeding cessation4, the rationale being that anxious or depressed women had a harder time meeting nursing demands. However, according to a huge Norwegian study of 42,225 women, it's the other way around. Researchers in the Norwegian study found that halting breastfeeding in the first six months predicted increases in anxiety and depression, even when taking into account previous mental health history, type of delivery, smoking and preterm births5.

Other studies have confirmed that women with negative breastfeeding experiences--the same ones who are more likely to stop the process--have higher levels of postpartum depression, going so far as to recommend that women who are having trouble nursing be screened for depressive symptoms6. Still other reports note that the cessation of breastfeeding significantly compounds mental health issues, particularly in women who have a history of anxiety or depression7.

That's a big deal. It means that women who are encouraged to stop nursing in order to decrease anxiety related to demands of breastfeeding, or those encouraged to stop in order to begin medications, may actually make the symptoms worse. (Plus, there are many medications that are able to be taken during breastfeeding should a woman need this.)

But why would breastfeeding be protective against PPD?

Evolutionary Links Between Postpartum Depression and Breastfeeding

The reasons for this are still under debate, although many anthropologists, biologists and evolutionary psychologists attribute depression at breastfeeding cessation (either early or in later months) to the fact that ancestral children would not have survived without it. To wean prematurely may trigger an innate drive that leads some part of the brain to assume a woman should be upset because she is now (or would soon be) childless.

The subconscious mind is a bitch sometimes.

Anthropologist Sarah Blaffer Hrdy discusses this concept in her book Mother Nature3.  According to Hrdy, breastfeeding is a biologically expected response postpartum, in that this would have been the only way to keep an infant alive on the savannah. If an ancestral mother did not nurse, there were only a few reasons for this and they are the only ones innate,  subconscious brain systems recognize: either the child did not survive or the mother had not decided whether the environment was secure enough to keep the child in the first place.

The plot thickens.

So how does a mother know she's invested? Aside from pure food survival reasons, nursing evolved as a mechanism to promote attachment, both from baby to mother, and mother to child. Maternal attachment, or investment, is often overlooked, but it is a critical piece in the postpartum puzzle. 

According to Hrdy, the two to three day (or so) period before milk "comes in" is a reflection of the limited time period mothers had to decide whether or not they would invest in their child. After nursing begins, and the oxytocin starts flowing, few mothers are able to leave the child behind regardless of fitness implications.  This might also explain why women who are highly stressed have more issues with milk supply (though the vast majority never have supply issues if they nurse on demand). Wasting valuable milk and fat stores on a child not likely to survive because of an extremely stressful environment would have been a historically poor decision and may have been the only time that lower milk supply would have made sense. 

While infants are hardwired to attach automatically for their own survival, our investment is based on environmental conditions. Deciding not to breastfeed is an evolutionarily unexpected phenomenon that can lead to a cascade of PPD symptoms in a mother whose body believes that she cannot invest in the child or that she no longer has an infant to care for at all. The maternal return to work, where mothers are gone for far longer than would be expected even in cooperative breeding situations, may also lead these innate systems to believe that you are quite suddenly childless, triggering a barrage of depressive symptoms including PPD (This issue is discussed more in Mom Alert: How Contemporary Views of Attachment Can Cause Guilt (and why they might be wrong). 

Regardless of biological cause, there is a blind spot for many women surrounding the emotional consequences of choosing not to breastfeed. And let me be clear, this is not to say that every women who chooses formula will develop PPD. Postpartum Depression happens to breastfeeding moms too; it's not an all or nothing thing. This is only to say that choosing not to nurse may increase risks, not only for developing PPD in the first place, but also for having more severe symptoms. 

Women who choose formula clearly must be able to do so, and should not be subject to shaming or any other negativity for such choices. However, women may wish to weigh the potential emotional impact of feeding choices, particularly those with a history of anxiety or depression.  

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Topic-Relevant Resources

Mother Nature
Women, sex, competition, cooperative breeding and monkey heirarchies.

This Isn't What I Expected [2nd edition]: Overcoming Postpartum Depression
A great guide on combatting postpartum depression. You're not alone.

The Mother-to-Mother Postpartum Depression Support Book
A book on postpartum depression written by mothers, for mothers.

The Postpartum Husband: Practical Solutions for living with Postpartum Depression
A concise, practical guide full of useful information for the loved ones of those suffering with PPD

The Womanly Art of Breastfeeding
Information on breastfeeding practices, including how to do it and advice for breastfeeding problems

Mothering Through the Darkness: Women Open Up About the Postpartum Experience
Beautiful insight into the postpartum experience, this book uses personal essays to explore postpartum depression.