How Global Warming Threatens Your Pregnancy

Summer heatwaves, droughts, and wildfires are now an uncomfortable reality for pregnant women living on planet Earth today. Researchers are just beginning to understand better how rising temperatures threaten maternal and child health. Some of the most disadvantaged pregnant people will experience the most significant risk of harm from global warming, unless governments, companies, and people like you advocate for more comprehensive heat emergency plans. Learn how to keep safe and healthy as we enter warmer seasons during your pregnancy and how you can help raise awareness about global warming.

What Global Warming Looks and Feels Like For You

Regardless of where you live, you probably have already noticed some changes caused by global warming. Global warming is the long-term increase in Earth’s average temperatures. Signs of global warming we now are living with are:

  • Hotter cities and urban environments
  • Poorer air quality
  • More wildfires and forest fires
  • Higher sustained temperatures over time
  • Extreme temperatures (heatwaves)
  • Extreme weather events such as storms, flooding, tornadoes leaving people unhoused
  • Warmer temperatures and flooding increasing the number of ticks, mosquitos, and other insects causing viruses like Lyme or Zika that are harmful to pregnant women.
  • Rising food costs driven by droughts and changing weather patterns

Multiple public health agencies, climate scientists, and medical groups believe that you, because you are pregnant, are more vulnerable to these climate-related changes in our environment. Heat is one of the main drivers of the health risks global warming poses for maternal and child health.

How Heat Puts You and Your Baby At Risk When You Are Pregnant

The biggest problem for pregnant woman when it’s hot out is dehydration. Dehydration is the medical term for what happens if you can’t take in enough fluids or liquids to replace the amount of fluids your body loses through peeing, sweating, and breathing. Pregnant people can become dehydrated more quickly and easily than non-pregnant people. The risks of dehydration during pregnancy include:

One study by the National Institutes of Health found that women exposed to extreme heat waves during the first seven weeks of pregnancy were 11 percent more likely to go into labor early. People exposed to extreme heat throughout their pregnancy were also more likely to deliver early.

The other consequence of rising temperatures is poorer air quality. Heatwaves and extreme heat events cook the air and all of the chemicals and pollutants inside of it. This creates that ugly smog of unhealthy pollution closer to the surface of the Earth, in the air you are trying to breathe.

Research shows that increased heat, pollution and rising ozone levels during pregnancy cause low birth weight, preterm birth, and stillbirth. Exposure to pollution while pregnant, causes inflammation, changes the way your autonomic nervous system works, and can directly transport toxic chemicals through your placenta to your growing fetus. Another study, showed that preterm birth rates fell by more than one-quarter (27%) in regions close to several oil- and coal-fired plants after they closed between 2001 and 2011, confirming the causal relationship between exposure to air pollution during pregnancy and preterm birth.

How Heat Is Harmful to Your Infant

The most devastating consequence of extreme heat for babies is the heightened risk of stillbirth. Studies have shown that the rate of stillbirth increases by as much as 6 percent for every 1 degree Celsius increase during the third trimester. While 6 percent may seem like a small number, even one stillbirth, especially if it could be avoided, is a devastating tragedy.

Heatwaves, humidity, and high temperatures can also cause:

  • Dehydration
  • Sunburn
  • Heat exhaustion
  • Heat cramps
  • Heat stroke (a medical emergency)
  • Excessive exposure to unsafe air pollution levels
  • Wildfires resulting in poor air quality and lung damage from smoke inhalation
  • Disrupted sleep patterns
  • Difficulty breastfeeding

For these reasons the American Academy of Pediatrics recommends staying inside with your infant or toddler if the heat index (defined by the National Weather Service) is above 90 degrees Fahrenheit or higher. In the United States, the National Weather Service issues daily, location specific weather forecasts which you can use to find out the forecasted heat index, UV index (risk for sunburn), and air quality indicators.

How Heat Takes Its Toll Postpartum

Pregnant people and people who have recently given birth are at an increased risk for severe stress and other negative health outcomes due to extreme heat and weather-related disasters related to global warming.

  • Trouble producing enough breast milk
  • Difficulty establishing breastfeeding during a heatwave
  • Increased stress and negative mental health outcomes
  • Increased risk for preeclampsia and problems with high blood pressure postpartum
  • Delayed healing and increased risk of infection
  • Lack of access to important postpartum and infant pediatric doctors’ appointments if offices are closed or it is unsafe to leave your home due to the heat and air quality

Having to stay isolated inside your apartment because of a heatwave, worrying about encroaching fires, or having to leave your home because of floods can be devastating for new mothers and their infants.

For many pregnant and postpartum people the social determinants of health, or the conditions of their daily life increases your vulnerability to heat’s negative impact upon your fourth trimester. Your access to health care, housing and food insecurity, exposure to violence, and availability of air conditioning all make staying healthy more complicated and stressful.

How To Stay Cool and Healthy When It Is Hot And You Are Pregnant

  1. Watch for the signs of dehydration.
  2. Stay indoors or at least in the shade.
  3. Wear light, loose-fitting clothing, and a hat if you have to be outside.
  4. Use air conditioning, especially if the temperature is above 95 degrees Fahrenheit (35 degrees Celsius)
  5. Take a cold shower or bath.
  6. Eat light, cold foods such as fruit and salads. Try to avoid using the stove, which only adds additional heat to your house or apartment.
  7. If you work in a hot environment like a field or a factory, talk to your doctor about workplace accommodation to keep you healthy.
  8. If you can afford it, consider purchasing room air purifier to use during poor air quality days. Make sure to choose one with a HEPA filter.

What You Can Do To Raise Awareness

Not everyone is aware of how vulnerable pregnant people are to the impact of heat. Tell the people who care about you how global warming directly puts your pregnancy at risk. People are much more likely to care about an issue when they know someone who is affected by it.

In October 2020, the International NGO Human Rights Watch proclaimed that the climate crisis and the resulting increase in temperature are reproductive justice issues. Because of how our health and economic systems are structured, climate change threatens some pregnant people more than others. In the US, for example, women of color have fewer resources to fall back on in times of heatwaves, droughts, fires, or extreme weather events caused by global warming.

As the March of Dimes advocated in their recent webinar, “Reproductive Justice: Environmental Health and Maternal and Child Health,” applying a reproductive justice framework to climate change can help drive change. Without change, global warming will increasingly harm pregnant people’s babies and our planet’s health.

Amy Harris
Amy Harris is a certified nurse-midwife with a Master's Degree in Maternal and Child Health from Harvard Chan School of Public Health. Her passions are health literacy and women's reproductive health. A recent two-year sabbatical with her family in Spain was the impetus for becoming a freelance women's health writer. An exercise nut, she is happiest outdoors and on adventures abroad.

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