Mamas on Bedrest: Post Partum Depression-The Physiologic Reasons it Occurs, Part I

December 14th, 2012

Postpartum depression (PPD) affects nearly 1 million American women annually, and most women don’t realize that there are significant physical reasons for the disorder. No, you’re not just crazy, tired and “hormonal” The truth is that there are significant biochemical changes going on in the post partum woman’s body such that coupled with their normal physiology, many women are prime candidates for post partum depression. If you don’t believe me, please head on over to my colleague Katherine Stone’s website, PostPartum Progress. Katherine, who has been blogging about post partum depression for nearly a decade, presents the statistics on just how many women are affected by post partum depression annually and then goes on to apply the statistics to actual numbers which we can all understand. She’s done a wonderful job illustrating how widespread and potentially devastating post partum depression can be for women.

In case you don’t know, here are some of the Signs and Symptoms of Post Partum Depression, as outline on Post Partum Progress.

The Research

Alkistis Skalkidou and colleagues from the Department of Women’s & Children’s Health and the Department of Neuroscience, Uppsala University, Uppsala, Sweden recently published Biological Aspects of Post Partum Depression in Women’s Health.  (2012;8(6):659-671) In this article, the researchers give very specific biologic reasons for the occurence of post partum depression in women by comparing the neurological and endocrine (hormonal) changes that occur in “normal” pregnant women and those that occur in women at risk for developing post partum depression. There are real physical changes that occur that are often the underlying reason post partum depression occurs.

Neuropsychoendocrine Changes in Normal Pregnancy and Post Partum

The chemical and hormonal changes necessary for a normal pregnancy to occur are usually offset by other changes that balance them out. Estrogens, progesterone, testosterone, corticotropin-releasing hormone (CRH) and cortisol all rise dramatically during pregnancy and drop just as dramatically at delivery and in the early post partum period. These hormones are typically regulated by a complex feedback system, the Hypothalamic Pituitary Axis (HPA), that is temporarily suspended during pregnancy to allow for the necessary hormonal increases needed to sustain fetal growth and development.

The adrenal glands are upregulated to produce more cortisol, necessary for fetal growth and development. But this additional adrenal output allows for cortisol levels to reach 3 times their non-pregnant levels, while at the same time depressing the fight or flight response. Prolactin levels steadily increase during pregnancy and at delivery are some 10 fold greater than in non pregnant women. Prolactin allows for milk production, yet prolactin, which crosses the blood brain barrier, contributes to the sustained inhibition of the HPA in the post partum of breastfeeding women.  Thus, hormone levels that were previously high as the HPA was shut down, drop dramatically and the normal regulation systems don’t detect the decreased levels and restart hormone production.

The nervous system has a similar down regulation resulting in a lowered response to stress in pregnant women versus non-pregnant women, and this persist while women breastfeed. Startle responses are diminished and women have been found to have a decreased reaction to emotional stimuli in the post partum versus in the latter stages of pregnancy.

Finally, neurotransmitter (brain chemical) levels are decreased in pregnant and newly post partum women. Increased activity of the enzyme Monoamine Oxidase reduce the levels of the brain chemicals serotonin, norepinephrine and dopamine-all responsible for stabilizing mood. GABA (another mood stabilizer) levels are also decreased in pregnant and post partum women, leading to serotonin deficiency. Combined with other neurochemical changes, to date it has been noted that post partum depression is primarily a state of serotonin deficiency.

So as you can see there are real, physical reasons that post partum depression occurs. Many complex changes occur during pregnancy and while they most often re-regulate themselves after delivery, some women’s bodies will not as readily re-regulate, sometimes due to the stress of pregnancy, sometimes due to genetic predispositions. Regardless of the reason it is occuring, PPD is a serious medical condition that is the result of physical, biological changes.

The major problem with post partum depression is underdiagnosis. Mental health disorders continue to be a source of shame in this country. Many women have the mistaken belief that if they are not euphoric after the birth of their blessed children, then there is something wrong with them of which they should be ashamed and it should be hidden at all costs. Nothing could be further from the truth! Post partum depression is an actual physical disorder in which the body’s chemicals are significantly imbalanced leading to impairments in thoughts, judgements and reasoning. The good news is that there is treatment for post partum depression. The bad news is that women are seldom forthcoming with (or are even familiar with) the signs and symptoms of post partum depression to raise the issues with their health care providers.  Health care providers should, at regular intervals during the later phases of pregnancy and throughout the post partum period, ask targeted questions of their patients to screen them for post partum depression as well as other mood disorders.

In the next installment of this discussion, we’ll look at how the physical changes contribute to PPD in women and how treatments help women’s bodies re-regulate.

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