Cold Exposure & Pregnancy

In Finland and other Nordic countries, outdoor winter swimming—often alongside sauna use—is a deeply ingrained cultural practice known as avantouinti. It’s especially popular and socially accepted among women who have practiced it regularly prior to pregnancy. Within these communities, continuing the tradition during pregnancy has been reported by seasoned winter swimmers, often with medical guidance and habit-based confidence.

While no large-scale studies focus exclusively on pregnant Scandinavian swimmers, the established tradition and cold tolerance built over years offers a broader anecdotal foundation.

More recently, women within the biohacking community are experimenting with cold water immersion (via showers or pools) as a way to mitigate some of the discomfort and biological shifts that occur during pregnancy.

• Sophie Hellyer (outdoor swimmer)

• Swam almost daily throughout pregnancy, even into late third trimester

• Reported that cold swims were mentally refreshing, calming, and energizing, helping stave off prenatal depression and anxiety

• Noted relief from swelling in feet and ankles, citing anti-inflammatory effects of immersion and the feeling of weightlessness in the water

• Limited her immersion to 2–5 minutes in ~8 °C (~46 °F) water, always followed by warm re‑drying and clothes to avoid “afterdrop”

• Other self‑reported users in pregnancy forums

• Some women describe light cold exposure (cold showers or swims) offering nausea relief and improved mood

• Others reported enhanced mental well‑being and decreased prenatal stress, citing energizing effects of cold exposure

Expert & Academic Observations

• Hypothesis and Published Literature

• A 2020 hypothesis paper proposes that habitual cold water swimming before and during pregnancy may help buffer stress responses and potentially improve birth outcomes for regular swimmers

• Guidelines from Maternal Health Experts (University of Plymouth study, March 2025)

• Consensus-based expert guidance recommends cold swimming only if you were already a regular cold swimmer before pregnancy, always avoid swimming alone, and do not engage in it if you have high or low blood pressure

• Researchers noted only six published studies connecting pregnancy and cold swimming; no statistically robust outcomes—highlighting a major research gap

• Immersion helped reduce leg and ankle edema (fluid retention) and odd observations like reduced restless leg syndrome in short immersion studies, though cortisol responses were inconsistent (a pregnant hand‑immersion cold stress test did not raise cortisol)

Building Stress Resilience for Labor

During pregnancy, especially in the second and third trimesters, the body undergoes intense physiological changes that can strain cardiovascular, metabolic, and nervous system balance. Introducing gentle, controlled cold exposure during this time may offer a unique way to train the body to better adapt to stress, making labor and recovery more efficient.

This concept is rooted in hormesis—the biological principle that small, manageable stressors activate beneficial adaptive responses.

What Is a Hormetic Stressor?

Hormesis refers to a mild or intermittent stress that strengthens the body’s resilience to greater stress later on. Common examples include:

• Fasting

• Exercise

• Heat therapy (e.g., sauna)

• Cold therapy (e.g., plunging, cold showers)

In pregnancy, especially after 34-36 weeks, the goal is not to “stress” the body in a harsh way, but rather to prime the system for adaptation—a crucial preparation for the intense physical and hormonal demands of labor and postpartum.

Benefits of Cold Exposure as Hormetic Conditioning Before Labor

1. Improved Nervous System Regulation (Vagal Tone)

Cold exposure increases parasympathetic activity (rest-and-digest state) after the initial sympathetic spike. With consistent use, this helps:

• Lower baseline cortisol

• Build better emotional regulation

• Support clearer mind–body awareness during labor

A regulated nervous system allows for better pain modulation, fewer panic responses, and stronger uterine coordination during birth.

2. Enhanced Mitochondrial Resilience

Pregnancy is an energetically expensive state. Cold exposure activates PGC-1α, a master regulator of mitochondrial biogenesis (the creation of new mitochondria), enhancing:

• Energy production in muscles (including the uterus)

• Cellular resilience during contractions

• Recovery and tissue healing postpartum

This may be especially beneficial as mitochondrial efficiency declines in late pregnancy due to oxidative stress and inflammatory burden.

3. Reduced Inflammation & Edema

Cold exposure decreases pro-inflammatory cytokines (e.g., IL-6, TNF-α) and increases anti-inflammatory signals (e.g., IL-10, adiponectin), which can:

• Relieve joint pain, swelling, and pelvic pressure

• Decrease risk of preeclampsia and gestational hypertension (when not contraindicated)

• Support smoother tissue recovery after delivery

4. Increased Pain Tolerance

Regular exposure to cold strengthens mental and physical pain tolerance. This may:

• Improve labor endurance

• Train breathwork and mental focus in moments of discomfort

• Reduce reliance on pharmacologic interventions (though not always a replacement)

Some midwives liken cold immersion to a “dry run” for labor: you learn to breathe, surrender, and regulate.

5. Enhanced Blood Sugar Regulation

Insulin resistance increases in late pregnancy. Cold therapy can:

• Improve glucose uptake in muscle and brown fat

• Lower fasting insulin

• Support stable energy levels for labor and postpartum

This may be especially helpful for women managing gestational diabetes or PCOS during pregnancy.

6. Circulatory Benefits & Cardiovascular Conditioning

Cold exposure trains vascular tone, helping blood vessels contract and dilate more efficiently. This “vascular fitness” may:

• Support oxygen delivery to the uterus and placenta

• Reduce fluid retention and blood pooling

• Prepare the heart for the intense output required during labor

Anecdotal & Community-Reported Feedback During Pregnancy

Though rare, some pregnant women have shared experiences of improved mood and emotional well-being with light cold exposure:

• Within wellness blogs and motherhood forums, women approved by their providers but cautious in practice described brief cold showers or mildly cool immersion (55–60 °F) as giving them a mood lift, clearer mind, and calmness during emotional challenges of pregnancy.

Cautions & How to Do It Safely

• Never cold plunge during pregnancy unless you were already adapted prior or have explicit OB/midwife clearance

• Always use moderate temps (55–60°F / 13–15°C) and short durations (1–2 minutes max)

• Avoid any plunge that causes shivering, dizziness, or breath retention

• Always rewarm gently afterward

• Stay hydrated and nourished

• Best done in second or early third trimester, not late third trimester when blood pressure variability and fetal position may complicate safety

Suggested Protocol for Late Pregnancy (If Cleared)

• Temperature: 55–60°F (13–15°C)

• Duration: 1–2 minutes max, 2–3x/week

• Timing: Not right before bed, not in fasted state

• Rewarm: Warm clothes, breathwork, and hydration afterward

• Mental focus: Use as a practice in labor-style breath regulation and surrender

When to Start Cold Plunging in Pregnancy (If Approved)

Best window: 14–34 weeks (mid-2nd trimester to early 3rd trimester)

Why?

• 1st trimester (0–13 weeks) is generally not recommended for cold plunging. This is a critical period for:

  • Placental development

  • High sensitivity to stress and cortisol

  • Higher risk of miscarriage (cold-induced vasoconstriction may reduce uterine blood flow)

• 2nd trimester (14–27 weeks) is the safest and most stable time for gentle cold exposure if:

  • The woman has been previously adapted to cold exposure

  • There are no signs of preterm labor, preeclampsia, or cardiovascular instability

• Early 3rd trimester (28–34 weeks) may still allow short-duration, moderate-temp plunges if swelling, blood pressure, and fetal growth are healthy.

When to Stop Cold Plunging

Stop by 34–36 weeks at the latest, or earlier if:

• Blood pressure becomes elevated or drops suddenly

• Fetal movement changes

• Any signs of preterm labor occur (tightening, back pain, contractions)

• You feel lightheaded, breathless, cold to the core, or faint

• Baby is breech or transverse and hasn’t turned by week 32–34 (vasoconstriction may inhibit repositioning)

As always, this must be individualized and done with clinical support. The best outcomes occur in women who were already familiar with cold therapy before pregnancy and approach it with respect, moderation, and intuition.

If cold therapy is something you would like to include in your pregnancy support, we strongly encourage you to begin the practice 3-6 months prior to conceiving and ONLY with the approval and guidance of your OB/Midwife. We have witnessed several moms experience profound benefits from cold water immersion during pregnancy, and have claimed that “simulation” of birth practices through cold water immersion has been helpful as they prepare for labor and delivery.