Heat and humidity can go up in the summer months, making it feel hotter outside than normal. Extreme heat happens when the heat and humidity are much higher than we would expect during a normal summer day.

 Extreme heat can be harmful to anyone's health, but people who are pregnant or had a baby within the past 6 weeks may be at a higher risk, especially if they do not have access to a cool indoor environment. Weight normally gained during a pregnancy can make it harder for the body to maintain a safe body temperature during hot weather – this can lead to heat-related illness. 

Heat can build up indoors when the outdoor temperatures are high. Exposure to indoor heat over 31C for long periods can be dangerous. 

Extreme heat may raise the risk of pregnancy related complications. If it gets very hot in your home, plan to go somewhere cooler if possible. 

By protecting yourself from extreme heat, you can help reduce these risks. 

If you experience heat-related symptoms or increased contractions it is important to speak with your registered midwife, family physician, or obstetrician. You can also call HealthLink BC at 8-1-1 anytime to talk with a registered nurse.

What can you do to keep safe?

Keep a cool space

• Turn on air conditioning (AC) if you have it. A temperature of less than 26°C is safe for most people
• Indoor temperatures over 31°C for long periods can be dangerous
• Get a digital room thermometer as this will help you know when your home is getting too hot.
• If you do not have an air-conditioned space in your home, consider staying with friends or family who have air-conditioning if your house gets too hot.
• Go to local cooling centres or community spaces, such as libraries or malls
• Sleep in the coolest room in your home, even if it is not your bedroom
• Close windows during the heat of the day to trap cooler air inside
• Cover windows by using shutters, blinds, drapes, blankets or sheets to keep sun out during the day
• If the temperature drops at night and it is safe, open windows to let cool air in
• If you have a fan, use it to move air around the room. Try putting an ice tray in front of the fan. Keep in mind that fans might not help to lower your core body temperature when it is very hot
• Turn off lights and electronic devices that are not in use to avoid any extra heat
• Use your oven or stove as little as possible as this can spread heat throughout your home

Keep your body cool and hydrated

• Drink plenty of water and other fluids (about 3-4 litres of water a day), especially if you are breast/chest-feeding and even if you do not feel thirsty
• Avoid drinking large amounts of caffeinated, sugary or artificially sweetened and alcoholic drinks
• Eat fruits and vegetables. They have a high water content and can help keep you hydrated
• Take a cool shower or bath or try a sponge or foot bath. You can also use a personal spray bottle with cool water
• Try using a cold pack or wrap. You can also wear a damp shawl or shirt
• Use a damp sheet at night
• Wear light-coloured, loose-fitting, breathable clothing, sunglasses and a wide-brimmed hat if you are outside. Although light-coloured clothing is recommended to keep cool, it does not provide as much SPF protection from the sun’s rays as darker coloured clothing
• Protect exposed skin by wearing sunscreen with broad-spectrum coverage and a Sun Protection Factor (SPF) of at least 30
• Lower activity levels and avoid intense activity

If you are breast/chest-feeding, try to limit your caffeine intake to 300 mg per day (about 11/2 cups of coffee) and no alcohol intake. 

If you are tandem feeding during pregnancy, it’s important for you to stay hydrated. Try having a cool non-alcoholic, low-sugar drink during every feed in addition to other drinks throughout the day.

Keep out of the heat

• If you have to go outside, try to stay in cooler, breezier areas like large, shaded parks or spaces with water features and lots of trees
• Try to plan activities, such as going to appointments, during the cooler morning and evening hours. This might make it easier to stay inside in a cool place during the hottest hours of the day
• If you work outside or in an environment that does not have a good cooling system, such as air-conditioning, talk to a health care provider or workplace safety officer to find out what measures exist to reduce your risk of heat-related illness

What are symptoms of mild to moderate heat-related illness?

Some symptoms of mild to moderate heat-related illness include:

• Irritability
• Thirst or dry mouth
• Fast heart rate even when resting
• Feeling generally unwell
• Heavy sweating
• Muscle cramps
• Heat rash or heat edema (swelling)
• Swelling, especially in hands and feet
• Fatigue, weakness, and malaise
• Feeling light-headed or dizziness
• Headache
• Disorientation
• Peeing less, and urine is very dark
• Body temperature of greater than 38°C (100°F)
• Nausea that is new or different than any pre-existing nausea in pregnancy

Most mild/moderate heat-related illnesses, sometimes called heat exhaustion, can be treated at home if they are caught early. If you are showing signs of mild/moderate heat-related illness, start cooling yourself down right away. If your symptoms last longer than 1 hour, change, worsen or cause you concern, contact a health care provider. If you are unsure about your symptoms, you can call HealthLink BC at 8-1-1 anytime to speak with a Registered Nurse.

What are symptoms of severe heat-related illness?

Some symptoms of severe heat-related illness include:

• Hot and flushed or very pale skin
• Not sweating
• Severe nausea and/or vomiting
• Fainting or loss of consciousness
• Increased heart rate and rapid, shallow breathing
• Unusual confusion and decreased mental alertness
• Feeling lethargic
• Difficulty speaking
• Unusual coordination problems
• Peeing very little, and urine is very dark
• Body temperature of greater than 39°C (102°F)

Call 9-1-1 or your local emergency number if you suspect a severe heat-related illness and keep trying to cool yourself or the individual you are caring for until help arrives. While waiting for help to arrive, cool the person by:

• Moving them to a cool place, if you can;
• Removing excess clothing;
• Applying cold water, wet towels, or ice packs around the body, especially the neck, armpits, and groin.

Signs of heat related illness can also be similar to other complications that can arise in pregnancy and the postpartum period. Many pregnant people have lower blood pressure during early pregnancy. Warm conditions bring blood to the skin to get rid of excess heat, potentially making blood pressure even lower. This can result in headaches, feeling light-headed, or even fainting. Any of the symptoms of heat related illness can be worsened if the person has underlying conditions such as obesity, kidney disease, or heart issues.

Contact your healthcare provider or go to the hospital right away if you experience:

• Decreased fetal movement
• A trickle or gush of fluid or bleeding from your vagina that doesn’t stop after going to the bathroom
• Stomach pains or bad cramps that won’t go away
• Unusual lower back pain or pressure
• Contractions that don’t go away when you walk, rest, or take a warm shower
• A feeling that something isn’t right

Many pregnant people experience Braxton Hicks contractions (or tightening in the abdomen that comes and goes). Dehydration can make these worse. Hot weather has not shown to cause early labour. It is still important that anyone who experiences more tightenings than usual in the abdomen should be checked by their midwife, doctor, or obstetrician.

BC’s heat alert warning system

The B.C. Heat Alert and Response System, or BC HARS, defines two categories of heat events – heat warning and the more dangerous extreme heat emergency – triggered by specific temperature ranges to initiate recommended response actions. Environment and Climate Change Canada issue the alerts and you can sign up to get heat push notifications to your smartphones through the WeatherCAN app for any/all of the pre-selected locations.

For more information

For more information on extreme heat, see: https://www2.gov.bc.ca/assets/gov/public-safety-and-emergency-services/emergency-preparedness-response-recovery/embc/preparedbc/preparedbc-guides/preparedbc_extreme_heat_guide.pdf

For more information on heat-related illness and keeping children safe during extreme heat, see:

• HealthLinkBC File #35 Heat-related illness
• HealthLinkBC File #35b Safety for infants and young children during extreme heat

For more information on foods and drinks to limit or avoid during pregnancy or breast/chest-feeding, please visit:

• Baby’s Best Chance
• HealthLinkBC File #38d Pregnancy and alcohol use

For information about preterm labour, please visit:

• HealthLink BC File Preterm Labour