Cortisol and Pregnancy: What You Need to Know

You’ve probably heard about cortisol before–the stress hormone has gotten its fair share of time in the spotlight. But do you know the connection between cortisol and pregnancy?

During pregnancy, this critical hormone naturally rises to support your baby's development. For most women, it’s an insignificant rise that’s largely not harmful to them or their baby. However, chronically elevated cortisol levels may affect fetal development, birth outcomes, and your own well-being. Here's what the science actually says, and what you can do to support a healthy balance throughout your pregnancy.

What Is Cortisol and Why Does It Matter in Pregnancy?

Cortisol is a hormone produced by the adrenal glands in response to physical or emotional stressors.

Despite its bad rep, cortisol plays a central role in regulating metabolism, blood sugar, inflammation, and your sleep-wake cycle, called the circadian rhythm. Normally, cortisol follows a natural daily rhythm–peaking in the morning to help you wake and gradually winding down through the evening so you can fall asleep.

During pregnancy, cortisol takes on additional responsibilities. It supports fetal organ maturation, helps regulate blood glucose for both mother and baby, and plays a part in the timing and onset of labor. Cortisol function in pregnancy is genuinely essential. The goal isn't to eliminate it; it's to understand when levels shift beyond what's helpful.

How Cortisol Levels Change During Pregnancy

Pregnancy is one of the only times in a person's life when cortisol levels rise significantly as a matter of biological design, and not necessarily due to any dysfunction.

Why Cortisol Naturally Rises

As pregnancy progresses, the placenta begins producing a hormone called corticotropin-releasing hormone (CRH). This triggers a rise in maternal cortisol, particularly from the second trimester onward. By late pregnancy, cortisol levels can be two to four times higher than the pre-pregnancy baseline.

While that sounds alarming, it’s not a cause for concern. Elevated cortisol levels are key to the baby’s development, helping prepare their lungs for breathing. The extra cortisol also supports the energy demands of late pregnancy and contributes to the biological signals that initiate labor.

What Counts as "High" Cortisol in Pregnancy?

Because pregnancy already substantially elevates cortisol, your provider will be looking for levels that exceed the “pregnancy-adjusted normal range.” That also varies by trimester, with the level steadily increasing as labor approaches.

Cortisol (Serum/Plasma)

How to Measure Cortisol Levels During Pregnancy

Your provider measures cortisol levels in two ways:

1. Blood serum, measured in saliva samples typically taken throughout the day
2. A hair sample, which can capture a cumulative cortisol exposure over months, rather than a single snapshot

If you have concerns about excess cortisol, speaking with your healthcare provider is the first step, as they can order the necessary tests and provide counsel on pregnancy-safe stress relief options.

Risks Associated With High Cortisol Levels in Pregnancy

Elevated cortisol levels aren’t always harmful–you need to take into account severity, duration, and any pre-existing conditions. 

Effects on Fetal Growth and Development

A growing body of research suggests that prolonged exposure to elevated maternal cortisol may influence fetal brain development — particularly structures involved in emotional regulation, like the amygdala. 

Additionally, researchers found that timing may have an impact. Chronic stress earlier in a pregnancy has been associated with slower cognitive development in the first year of life, while elevated cortisol later in pregnancy has been linked to accelerated development.

It's important to note that these are population-level associations, not individual predictions. Stress during pregnancy does not determine your child's outcomes.

Impact on Birth Outcomes

Multiple studies have linked chronically high cortisol in pregnancy to:

• A higher likelihood of preterm birth
• Lower birth weight and reduced fetal growth
• Potential complications associated with dysregulated placental CRH

A 2024 study from Washington State University found that women who experienced unpredictable birth complications had measurably higher hair cortisol concentrations in their third trimester, even when other risk factors were absent. Hair cortisol was a stronger predictor than self-reported stress — suggesting that the biological burden of chronic stress matters beyond how we consciously experience it.

Maternal Health Effects

For mothers, chronic cortisol elevation doesn't just affect the baby. It can worsen:

• Sleep quality — particularly sleep onset and overnight waking
• Anxiety and low mood
• Blood pressure regulation
• Energy levels and fatigue

Some research also suggests a link between cortisol and postpartum depression. One study found that women with higher cortisol levels had a much higher risk of experiencing PPD symptoms.

What About Low Cortisol in Pregnancy?

Low cortisol isn’t as common, but it can pose a problem. Generally, it’s a symptom of adrenal insufficiency, thyroid dysfunction, or Addison’s disease, a rare condition where damaged adrenal glands don’t produce enough cortisol.

If you become pregnant with one of the above conditions, you should speak with your healthcare provider ASAP for support managing your condition. Low cortisol is not something to assess or manage independently.

How Cortisol Affects Fertility and Early Pregnancy

Mild and occasional stress isn’t harmful, but there’s evidence that chronic stress can negatively affect ovulation and potentially implantation of an egg. However, many women with high-stress lives conceive without difficulty, so it’s not a sure thing.

If you have any concerns, such as irregular cycles alongside chronic stress, speak with your healthcare provider.

How to Support Healthy Cortisol Levels During Pregnancy

You can’t completely eliminate stress, but you can make some small changes to help build a nervous system environment that can recover from stress more effectively, and to avoid the patterns that keep cortisol chronically elevated. Much of this comes down to consistency and kindness toward yourself.

Lifestyle and Daily Habits

• Sleep: Cortisol follows a diurnal rhythm (highest in the AM and lowest in the PM), and disrupted sleep can throw it off. Aim for better sleep habits, like a consistent bedtime and reducing screen exposure before bed.
• Gentle movement: Adding regular, gentle physical activity, such as prenatal yoga, supports HPA axis regulation.
• Get Enough Sun: Time in natural light, particularly in the morning, supports circadian rhythm and cortisol's natural daily pattern.
• Reduce overstimulation: Often easier said than done, but it’s important to try to reduce triggers. The nervous system responds similarly to all stressors, so reduce ambient stress, particularly in the evenings. 
• Incorporate stress-relief techniques: Meditation, journaling, and breathwork are all mindful practices that can help reduce stress.

Don’t be afraid to turn to professional or social support as needed. Research suggests that effective social support during pregnancy acts as a buffer against chronically elevated stress. 

Nutrition and Supplement Considerations

What you eat shapes your body's capacity to regulate cortisol. A few evidence-informed principles worth building into daily habits:

• Blood sugar: Cortisol plays a vital role in blood glucose regulation, and instability can be a stressor. Eat a balanced meal that includes protein, healthy fats, and complex carbohydrates.
• Magnesium-rich foods: Research suggests that magnesium supplementation can mitigate HPA axis dysfunction. Needed’s Sleep + Relaxation Support is a pregnancy-safe supplement with 3 forms of Magnesium, L-Theanine, L-Glycine, and chamomile.
• Omega-3 fatty acids: Emerging research has identified these essential fatty acids as potential mediators linking maternal cortisol and adverse birth outcomes. Oily fish (where mercury levels allow), walnuts, flaxseed, and algae-based omega-3 supplements are worth discussing with your practitioner.

You should also limit caffeine, as it directly stimulates cortisol secretion. You shouldn’t take any supplements without consulting your provider first.

Frequently Asked Questions

Can high cortisol affect pregnancy?

Yes. Chronically elevated cortisol during pregnancy is associated with a higher risk of preterm birth, lower birth weight, and potential effects on fetal brain development. It may also increase the risk of postpartum depression. That said, cortisol naturally rises substantially during pregnancy, and occasional stress is not harmful — the concern is chronic, sustained elevation.

How can I lower cortisol while pregnant?

Evidence-supported approaches include consistent sleep, gentle movement and mindfulness exercises, and eating a balanced diet without caffeine. For significant anxiety or chronic stress, working with a perinatal mental health professional is the most impactful step.

How does cortisol affect getting pregnant?

Chronic stress and elevated cortisol can disrupt the hormonal signaling that regulates ovulation and menstrual cycle regularity. This may result in difficulties becoming pregnant, though it is highly individualized.

Is cortisol supposed to be high or low during pregnancy?

Cortisol naturally rises during pregnancy, especially in the third trimester, as your body prepares for delivery. Providers use the pregnancy-adjusted normal to determine what constitutes “high” levels. Low cortisol during pregnancy usually means an adrenal insufficiency or thyroid problem and should be discussed with your provider.

What causes abnormal cortisol levels in pregnancy?

Chronically elevated cortisol is most commonly associated with prolonged psychological stress, significant sleep disruption, and may even be associated with early-life adversity. Abnormally low cortisol is less common and typically associated with adrenal insufficiency or thyroid conditions. 

Summary and Key Takeaways

Cortisol is a necessary and expected part of a healthy pregnancy — it rises naturally to support your baby's development and prepare your body for birth. The concern is not cortisol itself, but when levels remain chronically elevated beyond the pregnancy-adjusted normal range. 

Research consistently links this pattern to a modestly higher risk of preterm birth, lower birth weight, fetal brain development changes, and postpartum depression. Healthy sleep, gentle movement, blood-sugar stability, nutrient support, and stress-reduction practices all meaningfully support cortisol balance during pregnancy. 

If you have persistent or overwhelming stress, speak with your healthcare provider so you can get the support you need for a healthy pregnancy.

Sources

1. Physiology, Cortisol - StatPearls - NCBI Bookshelf 
2. Cortisol on Circadian Rhythm and Its Effect on Cardiovascular System - PMC 
3. Placental corticotropin-releasing hormone, local effects and fetomaternal endocrinology - PubMed
4. Cortisol Levels in Third-trimester Pregnant Women
5. Pregnancy and laboratory studies: a reference table for clinicians - PubMed (Table) 
6. Maternal cortisol is associated with neonatal amygdala microstructure and connectivity in a sexually dimorphic manner | eLife 
7. The Timing of Prenatal Exposure to Maternal Cortisol and Psychosocial Stress is Associated with Human Infant Cognitive Development - PMC 
8. Perinatal hair cortisol concentrations linked to psychological distress and unpredicted birth complications - PubMed
9. Association of high cortisol levels in pregnancy and altered fetal growth. Results from the MAASTHI, a prospective cohort study, Bengaluru - PMC
10. Fertility and pregnancy in adrenal insufficiency - PMC
11. Role of yoga in stress management and implications in major depression disorder - PMC
12. The buffering effect of social support on hypothalamic-pituitary-adrenal axis function during pregnancy - PubMed 
13. An Integrative Approach to HPA Axis Dysfunction: From Recognition to Recovery - ScienceDirect
14. Association Between Fatty Acid Supplementation and Prenatal Stress in African Americans: A Randomized Controlled Trial - PMC