Reducing heat exposure can help improve outcomes for both expectant mothers and babies

By Melissa Lawlor, CNM, FNP-C, FF/EMT, fire commissioner, deputy coordinator for First Responder Health and Wellness 

You’re not just growing a baby; you’re creating life from scratch! One sleepless night and one hormone surge at a time. That’s nothing short of incredible. You’ve got a pregnancy swagger with every step you take. In the face of all the changes, you are powerful beyond measure. 

Now, imagine this: you’re on the line, battling flames or managing a rescue, feeling the heat seeping through your gear. You’re tough, resilient and ready to face anything. But what about your body, especially when you’re pregnant? Your job comes with occupational hazards, and extreme heat is one of them. 

This article is an open dialogue designed to provide you with the education and tools needed to advocate for yourself and your pregnancy. As a firefighter, you’re no stranger to extreme conditions. Understanding how those conditions impact your body and your baby is essential. 

We’ll delve into the risks associated with high heat exposure during pregnancy and equip you with the information you need to make informed decisions and confidently navigate your career while keeping both you and your baby safe. 

Making the Decision: When to Come Off the Line 

Deciding when to step back from front-line fire-suppression duties during pregnancy is one of the most significant choices you’ll face. This decision is deeply personal and should be made in partnership with your OB or midwife.

It’s crucial to discuss the specific job functions, physical demands, and exposures you encounter in your role with your healthcare provider. For support, you can refer to the OB/GYN Resource Guide for Firefighters provided by Science Alliance, which offers valuable information to share with your provider. 

Remember, this decision is yours to make. Only yours. No one else has the legal right to authorize or make this choice for you. The newly enacted PWFA protects your decision and request for accommodation. Once you decide it’s time to seek an accommodation, your fire department must collaborate with you to determine how best to support you. This process is designed to ensure you can continue working in a safe and manageable capacity, with your health and your baby’s well-being as priorities. 

Extreme Heat Environment 

Firefighters often work in immediately dangerous to life or health (IDLH) environments, where temperatures can soar beyond 200°C/392°F. Research shows that core body temperature in firefighters can exceed 38.5°C/101.3°F following interior attack structure firefighting, overhaul and wildland firefighting. 

Studies show that a maternal core body temperature of 39°C/102.2°F has been established as a teratogenic threshold, meaning it’s linked to increased developmental risks for the fetus. Understanding these risks is crucial for protecting both you and your baby while on the job. 

Another critical factor in firefighting is the outdoor ambient temperatures during extended rescue operations, auto extrications, EMS calls, brush and wildland fires, and other similar calls. Extreme heat is becoming increasingly common due to global warming, posing significant health risks, especially to vulnerable groups, including the elderly, children and pregnant women. 

As global temperatures rise, communities are facing more frequent and severe heat waves, which can overwhelm the body’s natural cooling mechanisms, leading to serious heat-related illnesses. Vulnerable groups are particularly at risk. 

For pregnant women, extreme heat can lead to complications such as pre-term birth and low birth weight. With climate change intensifying these hazardous conditions, it’s vital to prioritize the protection of these at-risk populations and develop strategies to reduce the impact of extreme heat on public health and our firefighters. 

Pregnancy Anatomy and Physiology 

Pregnancy is divided into three trimesters, each with its own unique stages of development. A full-term pregnancy typically lasts between 37 and 42 weeks. Babies born before 37 weeks are considered pre-term, which can lead to various health challenges. 

The first trimester spans from conception to 12 weeks, a critical period of early development. The second trimester covers weeks 13 to 27, a time of rapid growth and organ development. The third trimester, from 28 weeks to 40 weeks, is when the baby prepares for birth, with post-dates ranging from 40 to 42 weeks. 

Each trimester includes sensitive periods that can be particularly vulnerable to extreme heat exposure, which can have adverse effects on both the mother and the developing baby.

For further information, please go to Mother To Baby | Fact Sheets [Internet]. 

Here are interesting facts about pregnancy: 

● Your blood volume increases by 50 per cent

● Your heart rate and cardiac output go up 

● You gain extra fat stores 

● Your body surface area to body mass ratio decreases 

● The fetus is typically 0.5° warmer than your body 

● Dehydration becomes more common 

What do these facts have to do with extreme heat exposure during pregnancy? Let me explain. 

Normally, when a non-pregnant person gets too hot, their body cools down by widening blood vessels near the skin and activating sweat glands. But during pregnancy, extreme heat causes more cardiovascular stress by further increasing cardiac output and heart rate. Dehydration is also more common during extreme heat.

The extra fat stores in a pregnant body act as insulation, making it harder to cool down. Fat heats up faster than other tissues, and the baby’s metabolism adds to the mother’s body heat. The fetus, being slightly warmer than the mother, transfers this heat through the placenta, amniotic fluid, and uterus. 

By the third trimester, the increased blood volume makes the heart work harder under extreme heat. To cool the body, blood is redirected from vital organs, like the placenta and kidneys, to the skin. Pregnant individuals also have a lower threshold for sweating, making it even harder to cool down through evaporation. 

Adverse Outcomes for Extreme Heat Exposures 

Exposure to extreme heat during pregnancy can lead to several serious health risks for both the mother and baby. These risks include fetal anomalies, pre-term birth, low birth weight, stillbirth and premature rupture of membranes. 

Heat can also increase the chances of gestational diabetes, pre-eclampsia and reduced placental function. Additionally, extreme heat can cause dehydration, which may worsen if the mother experiences morning sickness, further increasing these risks through electrolyte imbalance. Heat exposure can also change how the uterus contracts and lead to inflammation, making pregnancy complications more likely. 

Here is what we currently know based on research: female firefighters face higher risks of adverse pregnancy outcomes compared to the general population. Pregnancies among firefighters are more than twice as likely to result in miscarriage compared to non-firefighters. 

Additionally, the prevalence of pre-term births is higher among firefighters, particularly those involved in wildland or combination firefighting. Volunteer firefighters, in particular, face a greater risk of pre-term birth than their career counterparts. 

Lastly, there are increased rates of babies born with low birth weight in firefighters. These findings suggest the unique occupational exposures and physical demands of firefighting contribute to increased risks during pregnancy. Extreme heat exposure may be one of the components. 

Heat Exposure Recommendations 

For pregnant firefighters, managing heat exposure is crucial for maintaining both maternal and fetal health. Here are some evidence-based recommendations to help navigate extreme heat conditions: 

Request accommodations: If you’re a pregnant firefighter, you have the right to request accommodations under the PWFA. These might include adjustments such as modified work schedules, more frequent breaks, appropriate uniforms, job restructuring, or access to cooler environments to help manage heat exposure. 

Heat risk management: Talk to your OB/midwife about your job descriptions and duties as a firefighter. Strategize ways to minimize occupational heat risks.

Hydration and nutrition: Drink extra water throughout the day, even if you’re not thirsty. Avoid sugary drinks, alcohol (obviously!) and limit caffeine. Opt for small, frequent, nutrient-dense meals and use cooking methods that minimize heat in your home and workplace. 

Cooling techniques: Use cold baths, showers, or damp towels to cool your body, focusing on areas like your face, wrists, and feet. Use fans to help evaporate sweat if temperatures are below 95°F (35°C). Rely on air-conditioned areas or cooling centers. 

Appropriate clothing: Wear loose-fitting, lightweight, and light-colored clothing. Use a hat and sunscreen with an SPF of at least 30 to protect your skin.

Workplace safety: If working outdoors or in hot environments, take regular breaks, use a buddy system, and hydrate in shaded or air-conditioned areas. Avoid peak sun hours if possible. 

Female firefighters face unique challenges during pregnancy. Yet, research suggests that reducing heat exposure can help improve outcomes for both mothers and babies. Your health and safety are crucial. Use the tips in this article, ask for the support you need, seek out PWFA accommodations, and know you’re not alone. Together, we can create a safer and healthier environment for you and your baby.