Research Brief: How Stress Affects Milk Supply

It’s no secret that breastfeeding can be challenging. Establishing and maintaining a breastfeeding relationship with your little one can cause significant stress, but stress can negatively impact breastfeeding. A new systematic review sheds light on the critical relationship between mothers’ stress levels in the postpartum period, milk supply, and the breastfeeding journey.

You can read the study's abstract (a short summary) here. The full-text version is currently only available behind a paywall, so we've accessed the full-text article ourselves and are here to explain the findings! The following research brief highlights the key findings of this systematic review.

Study Purpose

This systematic review aimed to summarize the research on maternal stress in the postpartum period, specifically looking at postpartum cortisol levels, and to determine whether there was a relationship between maternal cortisol levels and rates of exclusive breastfeeding. Let’s start by defining cortisol and “exclusive breastfeeding.”

Cortisol is the body’s primary stress hormone. It is secreted when the hypothalamic-pituitary-adrenal (HPA) axis is activated by a stressor. Despite its negative connotations, cortisol is not an inherently bad hormone! When secreted at modest levels, cortisol has multiple beneficial effects, helping your body manage inflammation, blood sugar, and a balanced stress response. However, excessive cortisol release has a detrimental impact on many bodily systems and processes, including, as we will discover, the breastfeeding process.

"Exclusive breastfeeding" is feeding your baby only breast milk with no other foods or liquids such as infant formula or water. As mentioned above, the WHO recommends that babies be exclusively breastfed for the first 6 months of life. The U.S. Dietary Guidelines for Americans also recommend 6 months of exclusive breastfeeding. While these guidelines have good intentions towards optimizing infant nutrition and health, the guidelines don’t necessarily acknowledge the barriers that can stand in the way of exclusive breastfeeding. The systematic review highlighted here delves into one crucial potential barrier to exclusive breastfeeding – maternal stress. 

Study Design

This study is a systematic review. A systematic review summarizes the existing research on a particular topic. This systematic review searched four databases and ultimately selected 15 studies to be included in the review. The following search terms were used to select articles: Cortisol, breastfeeding, and stress. The researchers also searched for relevant articles in the journal Breastfeeding Medicine and reviewed "suggested publications" generated during the search process. All observational study designs were eligible for inclusion in the systematic review.

Each study that was ultimately included in the systematic review examined how cortisol influenced the rate of exclusive breastfeeding upon discharge from the hospital.

Systematic Review Findings

The systematic review revealed that cortisol levels in postpartum mothers are a reliable indicator of the level of stress a mother is experiencing and are negatively correlated with hormonal factors that govern breast milk production, namely oxytocin and prolactin. In other words, high stress corresponded with lower hormones necessary for breast milk production and secretion, thus impacting a mother's breastfeeding ability.

In addition, mothers' perceived stress was related to exclusive breastfeeding rates. First-time mothers may experience a higher perceived stress level than mothers of multiple children, which correlates with higher cortisol levels and more breastfeeding complications that may affect breastfeeding success.

Mothers who experience childbirth as a stressful event due to interventions such as a C-section may also experience more difficulty with breastfeeding due to reductions in oxytocin and prolactin.

Finally, the stress associated with going back to work, financial stress, and postpartum mental health challenges, such as postpartum depression, may also impede breastmilk production and lead to lower exclusive breastfeeding rates.

Why This Research Matters

Breastfeeding provides an incredible source of nourishment for babies, but it can come at a cost for mothers. When a mother is stressed out, it not only affects her mental health, but it can also affect her milk supply due to the inhibitory effects of cortisol on the hormones oxytocin and prolactin which are necessary for breast milk production. When women face barriers like low milk supply, it tends to make them less likely to exclusively breastfeed.

We’ve said it before - mothers need more support! They need support in managing stress during the postpartum period and beyond, and they need support and nourishment for their breastfeeding journeys. A proper support system, including an informed and prepared partner, an experienced lactation consultant, and helpful family members and friends can help reduce a mother's stress postpartum. Good nutrition also plays a vital role in stress management. Numerous nutrients, including dietary protein, high-quality carbohydrates, healthy fats, B vitamins, and omega-3 fatty acids, regulate the body’s stress response.

In addition, supplemental herbs, such as Holy Basil and Ashwagandha, found in our Stress Support supplement, can help support a balanced stress response during the postpartum period, potentially helping create a smooth and successful breastfeeding journey. 


World Health Organisation. (2019). Breastfeeding. World Health Organization; World Health Organization: WHO.

Fernandez-Vaz, C., & Gonzalez-Sanz, J. D. (2022). Cortisol, maternal stress, and breastfeeding rate at hospital discharge: A Systematic Review. Breastfeeding Medicine.

CDC. (2019, November 4). Breastfeeding: Recommendations and benefits. Centers for Disease Control and Prevention.

Meet the Author

Lindsay Christensen, MS, CNS, LDN, is a functional nutritionist and health writer with a deep passion for functional medicine. Lindsay has her B.S. in Biomedical Science and M.S. in Human Nutrition and is a Certified Nutrition Specialist (CNS) and a Licensed Dietitian Nutritionist (LDN).

Lindsay works as a nutritionist at The California Center for Functional Medicine, where she helps patients with various chronic health challenges, including Lyme disease and autoimmunity. In her private practice, Alpine Fuel Nutrition, she provides holistic nutrition consulting to mountain athletes, including trail runners, climbers, skiers, and mountaineers. She has written for multiple health companies and publications, including Quicksilver Scientific, WellTheory, Paleo Magazine, WellBeing Journal, and Needed.

When Lindsay isn't working with clients or writing, she can be found trail running, mountaineering, skiing, and gardening in her beautiful home state of Colorado.