Should pregnant individuals be near campfires?

Pregnant People Should Avoid Campfire Smoke Exposure

Pregnant individuals should minimize or avoid exposure to campfire smoke due to documented risks of adverse perinatal outcomes including preterm birth, low birth weight, and pregnancy loss. The evidence clearly demonstrates that fire smoke contains harmful particulate matter (PM2.5) and toxic chemicals that pose significant risks during pregnancy 1.

Why Campfire Smoke Is Harmful During Pregnancy

Burning organic materials—whether from wildfires or campfires—produces:

• High levels of PM2.5 and ultrafine particles that can penetrate indoors and cross biological barriers
• Toxic chemicals including carbon monoxide, polycyclic aromatic hydrocarbons (PAHs), nitrogen and sulfur compounds, aldehydes, and free radicals
• Cytotoxic and mutagenic compounds with documented long-term health effects 1

These pollutants are small enough (<2.5 μm) to cause cellular damage and have been associated with adverse effects on both maternal and fetal health.

Documented Pregnancy Risks

The most recent evidence from 2025-2026 demonstrates:

Preterm Birth and Low Birth Weight

• Each 1 μg/m³ increase in wildfire PM2.5 increases odds of preterm birth by 3% (OR=1.03), very preterm birth by 7% (OR=1.07), and extremely preterm birth by 10% (OR=1.10) 2
• Birth weight reductions of approximately 8 grams per 24 hours of cumulative fire exposure 3
• Risk increases are steeper at lower-to-moderate exposures and plateau at higher levels 2

Congenital Heart Defects

• First-trimester exposure increases atrial septal defect risk by 11% (aOR=1.11) 4
• Critical window of vulnerability occurs during weeks 3-8 of pregnancy when fetal heart development occurs (aOR=1.12) 4

Other Adverse Outcomes

• Pregnancy loss and stillbirth 1
• Gestational diabetes mellitus and premature rupture of membranes 1
• Potential long-term respiratory effects in offspring 1

Critical Windows of Vulnerability

The second trimester and early first trimester (weeks 3-10) appear to be particularly vulnerable periods:

• Week 10 exposure shows strongest association with preterm birth (RD=0.030) 5
• Weeks 3-8 are critical for cardiac development 4
• Second-trimester exposure consistently relates to greater odds of adverse outcomes 2

However, all trimesters show increased risk, so avoidance throughout pregnancy is warranted 4, 2.

Special Considerations for Carbon Monoxide

Beyond particulate matter, campfire smoke contains carbon monoxide (CO), which poses unique risks:

• Fetal distress and fetal death are specific concerns with CO poisoning 6
• The fetus is particularly vulnerable because fetal hemoglobin has higher affinity for CO than adult hemoglobin
• Adult treatment criteria for CO poisoning are applied to pregnant patients, and hyperbaric oxygen has been administered safely to pregnant women when needed 6

Practical Recommendations

Minimize exposure by:

• Avoiding sitting directly near campfires, especially in enclosed or poorly ventilated areas
• Positioning upwind from smoke when campfires are present
• Limiting duration of exposure when avoidance is not possible
• Being particularly cautious during the first and second trimesters
• Recognizing that even brief exposures can contribute to cumulative risk

Important Caveats

• Exposure is nearly ubiquitous: Recent data shows 98% of California pregnancies had some wildfire smoke exposure 2, suggesting complete avoidance may be impractical in many settings
• Population-level effects: While individual-level effect sizes may appear small (e.g., 8-gram birth weight reduction), these translate to clinically meaningful shifts at the population level 3
• Dose-response relationship: Risk increases with both intensity and duration of exposure 3, 2
• No safe threshold identified: Effects are observed even at lower exposure levels 2

The evidence consistently demonstrates that fire smoke exposure during pregnancy—whether from wildfires or campfires—carries measurable risks to maternal and fetal health, with the strongest and most recent data supporting avoidance strategies throughout pregnancy 1, 4, 2, 7.