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Part Two: Pregnancy & Birth: How women’s brain biology, hormones and mood relate!

Originally posted April 7, 2014.

In Part One, we looked at the hormonal-neurotransmitter feedback loops in a woman’s body and how they relate to mood during the menstrual cycle.

(the Hypothalamus-Pituitary-Adrenal Cortex Loop and the Ovarian-Hypothalamus-Pituitary Loop)

Today we look at a woman’s hidden hormonal shifts during pregnancy and birth.

Pregnancy and hormonal shifts

Pregnancy is a time of big physical, psychological and emotional challenges. There are big hormonal and life shifts.

In the first trimester, by the first six weeks of pregnancy, estrogen levels rise to three times more than during the menstrual cycle! Although estrogen is a precursor to serotonin, a mood stabilizer, a woman’s body needs time to adjust to all of the changes in her pregnant body. Progesterone levels also rise quickly. Progesterone is also implicated in depressive moods (Sichel and Driscoll, 1999).

In the first trimester, in addition to the rapid hormonal changes which can cause anxiety and depression, a woman’s personal psychological and emotional adaptations to pregnancy are being played out.

What if the pregnancy was unplanned? What if this pregnancy follows a stillbirth? What if her primary relationship is not going well? All of these emotional considerations require attention and adjustment.

No wonder the first trimester can be unpleasant physically and emotionally to many women.

As the pregnancy progresses through the second and third trimester, along with elevated estrogen and progesterone levels, the hormones cortisol, prolactin and oxytocin rise. Cortisol is a strong player in the HPA feedback loop. High levels of cortisol are also associated with depression. And prolactin is also associated with anxiety, anger and irritability (Sichel and Driscoll, 1999).

Oxytocin is known as the bonding and happiness hormone. Natural oxytocin causes nutrition absorption, uterine contractions, pair-bonding, mother-infant bonding, pain amnesia, calmness and feelings of belonging and happiness (Buckley, 2013).

As a woman’s body and brain absorbs all of these changes, as her central HPA axis strives to adapt to these changes, so does she strive to adapt her emotional and psychological perspective on her pregnancy and motherhood.

We really have no way to assess the impact of all these hormonal changes on an individual woman, but we can keep this background information in mind as we support the pregnant mom in her journey to motherhood.

Birth and hormonal shifts

During a woman’s uninterrupted birth, there is a surge of oxytocin, beta-endorphin, adrenaline, noradrenaline and prolactin. These hormones all combine to orchestrate the event of birth. Oxytocin for uterine contractions, calmness, love. Beta-endorphins for a protective emotional high during a peak physical activity. Adrenaline rush for energy and the final push of the fetal ejection reflex. And high prolactin levels to consolidate breast milk production and breastfeeding.

Now add to all of these hormonal changes, modern medical interventions used in birth.

Medical interventions during birth all have an effect on a woman’s neuro-endocrine system. Synthetic oxytocin is often used to induce labor. Synthetic oxytocin causes strong uterine contractions but without the protective benefit of accompanying feelings of bonding, belonging and calmness. Oxytocin, synthetic or not, that is introduced externally or exogenously, via the bloodstream, can’t cross from the body to the brain. It’s also called not be able to cross the blood-brain barrier. Only oxytocin produced inside the brain, or endogenously, influences the brain by being able to bond to the oxytocin receptors in the brain. Endogenous oxytocin also physically increases the presence of oxytocin receptors in the brain. So exogenous oxytocin emotional effects are different than endogenous oxytocin emotional effects. But research has not yet been done to study this unique difference on a woman’s birth experience, mood and well-being after childbirth.

Other birth interventions, such as epidurals and cesarean sections in some way, interrupt the peak hormonal levels of oxytocin, endorphins, cortisol and prolactin which are naturally present at birth. But research has not yet been done to study this unique difference on a woman’s birth experience, mood and well-being after childbirth.

In addition, it’s well known that medical interventions, even when necessary, are known to cause post-traumatic stress disorder symptoms. A body of research is building up on the study of traumatic childbirth. A large amount of research shows that a medically traumatic birth, even if necessary, has an aftermath of post-traumatic stress disorder, often with accompanying co-morbid depression and anxiety (Beck, Sichel and Driscoll, 2013).

In Part Three, we’ll look at what happens to the postpartum hormonal mix.


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