Postpartum Depression Biology

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After The Baby

Postpartum depression strikes women at a time in their lives when they should be at their best – to care for their newborn baby. Instead, they feel sad, withdrawn, and hopeless - and have such a low energy level that it’s tough to tackle the challenges of being a new mom. What causes these feelings of sadness during a time which should be one of the happiest in their lives? What is postpartum depression biology?

It’s natural to assume that postpartum depression would have a genetic component since clinical depression is more common in certain families. Some research shows that postpartum depression is likely to have a genetic basis. One study found that 42% of women with a family history of postpartum depression experienced depression after their first delivery, but only 15% of women in families without a family history had depressive symptoms.

On the other hand, it’s difficult to say whether genetics was the only factor since environmental influences may have been similar within families. Like depression, there is evidence that genetics are involved in postpartum depression biology, but no specific gene or genes has been identified.

What’s Happening Biochemically?

When considering the cause of postpartum depression biology, it’s tempting to blame the symptoms on the hormonal fluctuations that occur as a woman’s body normalizes after the delivery of a baby. Levels of estrogen and progesterone drop precipitously after birth, but estrogen levels begin rising again soon after the baby is delivered, while progesterone levels lag behind. This creates an “estrogen-dominant” environment, which could play a role in postpartum depression.

There’s another way estrogen levels influence postpartum depression biology. According to recent studies, when estrogen levels drop after birth, the level of an enzyme called monoamine oxidase A (MAO-A) increases in the brain. When this happens, it causes neurotransmitters associated with mood to be broken down, including serotonin, norepinephrine, and dopamine. When levels of these neurotransmitters are altered, it leads to mood changes consistent with postpartum depression.

The Model

In a study published in Archives of General Psychiatry, researchers found that levels of MAO-A were 43% higher after a woman gave birth and were greatest around days five or six when many of the symptoms of postpartum depression usually begin. This offers an attractive model to explain postpartum depression biology.

What isn’t clear is why all women don’t experience postpartum depression since estrogen levels drop in all women after birth, which should trigger an increase in MAO-A levels. This is where genetics could come in. Some women may be genetically more sensitive to these fluctuations in hormone and neurotransmitter levels.

The Bottom Line

There’s still much to learn about the biology of postpartum depression and whether or not medications that alter MAO-A levels can help the problem of postpartum depression. Hopefully, further research will offer more answers and solutions for this common post-pregnancy disorder.


Am J Psychiatry. 2006 Sep;163(9):1549-53.

Archives of General Psychiatry. Vol. 67 No. 5, May 2010