Authored by Dr. Tali Bogler, Pina Bozzo, Anna Pupco and reviewed by First Exposure Medical Review Team.
Dr. Tali Bogler, MD, CCFP, MScCH, is a Medical Advisor at First Exposure, a Family physician, and Chair of Family Medicine Obstetrics at St. Michael’s Hospital, an assistant Professor, Department of Family and Community Medicine and Investigator at Li Ka Shing Knowledge Institute.
Pina Bozzo and Anna Pupco are Clinical Content Advisors at First Exposure.
This health topic is an expert opinion about common summer exposures during pregnancy.
* The information provided is the expert opinion of the First Exposure Medical Advisors. It is for informational purposes only and does not replace medical care and advice from a healthcare provider. Please contact your healthcare provider if you have any concerns or to discuss any questions that you believe may be relevant to you or your baby. In case of emergency, please go to the emergency room or call 911.
If you do not have a healthcare provider please go to: Finding a Healthcare Provider
Clinical scenario:
I am pregnant and entering the summer season in Canada. Is it safe to use sunscreen or bug spray and should I be worried about exposure to extreme heat while pregnant?
Summer poses unique challenges for pregnant women and pregnant individuals due to potential exposures to extreme heat as well as questions surrounding the use of insect repellants and sunscreen ingredients. Below is some information on how pregnant women and pregnant individuals can enjoy a safer and healthier summer.
Q. Are there any safety concerns with insect repellant (i.e. bug spray) use during pregnancy?
A. Insects such as mosquitos and ticks may carry diseases and can infect people through insect bites. In Canada, mosquitos may carry West Nile virus, and ticks may carry Lyme disease. In other countries mosquitos may carry Zika virus, dengue, and malaria. Some of these infections are known to be a concern in pregnancy. Because of this, it is important to try to prevent insect bites.
Some ways to prevent insect bites include:
- Wearing loose, light-coloured (mosquitoes are attracted to dark clothing), long-sleeved shirts and long pants made of tightly woven materials such as polyester or nylon
- Wearing closed-toe shoes and a hat
- Tucking in your shirt and taping the cuffs of your pants or tucking them inside your socks or shoes
- Use a Health Canada approved bug spray (insect repellent) on exposed skin.
During pregnancy, it is recommended to use an insect repellent that contains DEET as this is the only insect repellent studied in pregnancy. DEET (Diethyltoluamide) is a chemical that is found in commonly used insect repellants. The available information on the use of DEET in pregnancy has not found harmful effects to the pregnancy or the baby. In Canada, all approved insect repellants with DEET, contain less than 30% DEET. Health Canada approved bug sprays will have a P.C.P. (Pest Control Product) number on the packaging. If you purchase an insect repellant outside of Canada, make sure it also contains less than 30% DEET. Some important tips for using insect repellent include:
- Make sure to follow the directions on the packaging
- Do not spray in closed spaces
- Do not apply to skin under clothing. Rather apply to clothing and exposed skin
- Do not spray directly on the face. Spray your hands and apply to the face, avoiding contact with mouth and eyes
- Wash hands thoroughly after application
- Follow the directions on the product for the maximum number of applications allowed per day
For more information see Insect bite and pest prevention.
Q. Are there any safety concerns with sunscreen use during pregnancy?
A. Skin prick testing, a test that can be performed by an allergist, can help determine what someone is allergic to. Skin prick testing has a very low risk of a systemic reaction (whole body allergic reaction). Although the risk of a reaction is small, some allergists prefer not to do the skin prick test during pregnancy and prefer to wait to do it postpartum (after delivery).
Spending long periods of time in the sun may cause sunburn and skin cancer. Sunscreens provide protection from the damaging effects of the sun’s rays (radiation). It is preferred to use broad spectrum sunscreens that provide protection from both UVA and UVB rays. Sunscreens contain chemical UV filters, physical UV filters or a combination of the two. Chemical UV filters (eg. avobenzone, homosalate, octocrylene, octisalate, octinoxate and oxybenzone) work by converting UV radiation into a small amount of heat. These chemicals are absorbed into the skin but usually the amount that reaches the bloodstream is low. Physical UV filters (eg. zinc oxide and titanium dioxide) are mineral compounds that produce a physical barrier to UV radiation. These do not get absorbed into the skin.
There is not lot of data available on the effects of sunscreen exposure on pregnancy outcomes. Some people might prefer to use sunscreens that contain physical UV filters (e.g. zinc oxide, titanium dioxide) during pregnancy and while nursing, as they are not absorbed.
Some sun exposure tips include:
- Wear long-sleeved, light-coloured clothing and/or other protective clothing
- Stay in shaded areas such as under a tree or umbrella
- Use a Health Canada approved (will have an NPN or DIN) broad spectrum sunscreens with an SPF of 30 or higher
- Apply sunscreen 15 minutes before sun exposure
- Reapply sunscreen every 2 hours
For more information see sun safety and sunscreens.
Q. Are there any safety concerns with exposure to extreme heat during pregnancy?
A. In pregnancy there are changes that occur in the body, such as increases in body weight and more demand on the heart. These changes make it harder for a pregnant woman or pregnant individual to keep a normal body temperature when exposed to heat. Because of this they are more sensitive to heat and are at increased risks of heat exhaustion, heat stroke, and other heat-related illnesses. Prolonged exposure to extreme heat may also pose a risk to the pregnancy and baby. In some studies, increased rates of preterm birth (delivery before 37 weeks), low birth weight, stillbirth (loss of a baby before or during delivery) and gestational diabetes were reported following exposure to extreme heat. Studies have also reported a link between exposure to extreme heat in the first trimester and increased risk of birth defects. Some other adverse pregnancy outcomes, such as hypertensive (high blood pressure) disorders of pregnancy, have also been reported. However, more research on this topic is needed. It is not known at which temperature the risks may increase because studies used different definitions for high temperatures and extreme heat events. Given the concerns mentioned above, it is important to reduce your exposure to extreme heat as much as possible during pregnancy.
Tips to keep cool:
- Limit time spent outside during the hottest times of the day
- Avoid/limit physical activity in extreme heat
- Wear light, loose-fitting, breathable clothing
- Turn on air conditioning (AC) if accessible
- Go to places where you can stay cool such as libraries, community centres, malls, and cooling centres
- During the day, close windows to trap cool air inside and cover them (with shutters, blinds, drapes, sheets) to keep the sun out
- Sleep in the coolest room in your home (if your bedroom is hot)
- Turn off lights and electronic devices that are not in use to avoid generating extra heat
- Limit use of ovens and stoves to reduce heat in your home
- Keep hydrated by:
- Drinking fluids regularly throughout the day
- Limiting drinks high in sugars, sodium and caffeine as these may lead to dehydration
- Drinking water is usually best, but drinks containing electrolytes may be needed if sweating for many hours
- Those with nausea and vomiting of pregnancy need to be extra careful to avoid dehydration
For symptoms of heat-related illness please see Safety for the perinatal population during extreme heat.
If you are pregnant and feeling unwell due to heat exposure, seek medical attention. In case of emergency, please go to the emergency room or call 911.
For more information see:
Safety for the perinatal population during extreme heat
Clinical Guidance for Heat and Pregnancy for Healthcare Professionals
Key References
National Center for Environmental Health (US). Clinical Guidance for Heat and Pregnancy [Internet] Atlanta, GA: Centers for Disease Control and Prevention; 2024 [updated April 22, 2024; cited 2024 June 26]. Available from: https://www.cdc.gov/heat-health/hcp/heat-and-pregnant-women.html.
National Center for Environmental Health (US). Heat and Pregnancy [Internet] Atlanta, GA: Centers for Disease Control and Prevention; 2024 [updated April 22, 2024; cited 2024 June 26]. Available from: https://www.cdc.gov/heat-health/heat-and-pregnancy.html.
Cross SE, Innes B, Roberts MS, Tsuzuki T, Robertson TA, McCormick P. Human skin penetration of sunscreen nanoparticles: in-vitro assessment of a novel micronized zinc oxide formulation. Skin Pharmacol Physiol. 2007;20(3):148-54. [PMID: 17230054].
Dalugoda Y, Kuppa J, Phung H, Rutherford S, Phung D. Effect of Elevated Ambient Temperature on Maternal, Foetal, and Neonatal Outcomes: A Scoping Review. Int J Environ Res Public Health. 2022 Feb 4;19(3):1771. [PMID: 35162797] [PMC8835067].
Haghighi MM, Wright CY, Ayer J, Urban MF, Pham MD, et al. Climate Change And Heat-Health Study Group. Impacts of High Environmental Temperatures on Congenital Anomalies: A Systematic Review. Int J Environ Res Public Health. 2021 May 5;18(9):4910. [PMID: 34063033] [PMC8124753].
McGready R, Hamilton KA, Simpson JA, Cho T, Luxemburger C, et al. Safety of the insect repellent N,N-diethyl-M-toluamide (DEET) in pregnancy. Am J Trop Med Hyg. 2001 Oct;65(4):285-9. [PMID: 11693870].
HealthLinkBC. Safety for the perinatal population during extreme heat File #35a [Internet] Victoria, BC: British Columbia. Department of Public Health; 2024 [updated June 2024; cited 2024 June 26]. Available from: https://www.healthlinkbc.ca/sites/default/files/documents/hfile35a_Final.pdf.
Nyadanu SD, Dunne J, Tessema GA, Mullins B, Kumi-Boateng B, et al. Maternal exposure to ambient air temperature and adverse birth outcomes: An umbrella review of systematic reviews and meta-analyses. Sci Total Environ. 2024 Mar 20;917:170236. [PMID: 38272077].
Public Health Agency of Canada. Insect bite and pest prevention [Internet] Ottawa, ON: Public Health Agency of Canada; 2023 [updated October 27, 2023; cited 2024 June 20]. Available from: https://www.canada.ca/en/public-health/services/diseases/insect-bite-prevention.html.
Public Health Agency of Canada. Personal Insect repellents [Internet] Ottawa, ON: Public Health Agency of Canada; 2021 [updated June 2, 2021; cited 2024 June 20]. Available from: https://www.canada.ca/en/health-canada/services/about-pesticides/insect-repellents.html.
Public Health Agency of Canada. Sunscreens [Internet] Ottawa, ON: Public Health Agency of Canada; 2017 [updated November 7, 2017; cited 2024 June 20]. Available from: https://www.canada.ca/en/health-canada/services/sun-safety/sunscreens.html
Sarveiya V, Risk S, Benson HA. Liquid chromatographic assay for common sunscreen agents: application to in vivo assessment of skin penetration and systemic absorption in human volunteers. J Chromatogr B Analyt Technol Biomed Life Sci. 2004 Apr 25;803(2):225-31. [PMID: 15063329].
Wylie BJ, Hauptman M, Woolf AD, Goldman RH. Insect Repellants During Pregnancy in the Era of the Zika Virus. Obstet Gynecol. 2016 Nov;128(5):1111-1115. [PMID: 27548647] [PMC5737756].
Disclaimer
First Exposure does not offer health care treatment. If you have an urgent question about your pregnancy or your baby’s health, you should contact your health care provider directly. If you don’t have a health care provider and you live in Ontario, you have a variety of health care options. In the case of an emergency, visit a hospital emergency room or call 911.