How Do Cortisol Levels Affect Pregnancy?

Cortisol is a hormone released in response to stress, and moderate exposure during pregnancy is expected—but prolonged and excessive forms of it can be a concern. Moderate levels of cortisol help regulate normal fetal development, immune function, and metabolism. However, research shows that excessive and prolonged exposure to cortisol during pregnancy may affect the developing baby in measurable ways (Sandman et al., 2011).

How It Can Affect Your Baby

Scientific studies have linked elevated maternal cortisol levels to several prenatal and postnatal outcomes. These include:

Low Birth Weight and Prematurity

Excess cortisol can affect placental function and fetal growth, increasing the risk of preterm birth and low birth weight (Wadhwa et al., 1993).

Risk of Health Problems Later in Life

Prolonged exposure to high cortisol in utero has been associated with long-term changes in metabolic function and immune response, increasing the child’s susceptibility to chronic health conditions such as hypertension, obesity, or insulin resistance (Seckl & Meaney, 2004).

Altered Brain Chemistry and Stress Response

Cortisol plays a role in brain development, particularly in areas that govern emotional regulation and stress. Elevated levels during pregnancy may influence how a child responds to stress later in life, including a higher risk of anxiety or mood disorders (Davis & Sandman, 2010).

Cortisol and Breastfeeding: Insights from a Lactation Consultant

Certified lactation consultant and maternal mental health advocate Oryslawa Seidemann has worked with hundreds of new mothers navigating the postpartum period. In a recent conversation, she spoke about the connection between cortisol and breast milk production.

“If we stress ourselves out, we tense—our body is tenser. In order to really make more milk, you gotta have a relaxing experience... during stress, the cortisol level rises and has an impact, of course, on your production and then it affects the baby too.”
— Oryslawa Seidemann, MissPoppins Podcast, 2025

There is growing evidence that stress-induced cortisol may inhibit milk let-down and reduce milk supply (Groer & Davis, 2006). While this may not impact every breastfeeding parent, it highlights the importance of rest, emotional support, and stress reduction during the early postpartum phase.

Does Cortisol Affect You in the Postnatal Stage?

The role of cortisol doesn't end after delivery. Many mothers continue to experience elevated stress hormones during the postpartum period, particularly if they are managing physical recovery, sleep deprivation, and major life adjustments with minimal support.

“Whatever causes them stress will just really impact their maternal health, and that is connected to the infant's health, and then overall the family suffers.”
— Oryslawa Seidemann, MissPoppins Podcast, 2025

High cortisol levels postpartum have been associated with an increased risk of postpartum depression, difficulties with bonding, and disruptions to maternal-infant rhythm (Yim et al., 2015).

Cortisol Isn’t the Only Cause

It’s important to note that exposure to increased stress alone is not the sole contributor to possible health complications in your baby. Every pregnancy is different, and cortisol’s effect depends on several factors, including your medical history, genetic predispositions, the timing and duration of the stress, and the strength of your support systems.

Because of this, it’s essential to consult with a medical professional who can take a full view of your personal medical history.