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Middlesex-London Health Unit

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Hazards and Pregnancy

Many people worry about what puts their baby or themselves at risk before and during pregnancy. If you are pregnant or trying to become pregnant, learn how to find out more about how to reduce the risks.


Cannabis1 3 4

Cannabis use before, during and after pregnancy (PDF), and while breastfeeding, can be harmful to a baby. Legal does not mean safe.

  • The chemicals from cannabis can pass from the pregnant person's body to the baby during pregnancy, and from breastmilk to a baby when breastfeeding
  • Using cannabis during pregnancy may increase your baby's risk of developmental problems
  • Cannabis is not recommended as a treatment for nausea/vomiting during pregnancy
  • To avoid any possible negative health effects it is safest to avoid all forms of cannabis use while pregnant or breastfeeding
  • If you use cannabis and are pregnant or planning a pregnancy, talk with your healthcare provider

Get more information or help to quit cannabis and or other drugs.

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When a pregnant woman drinks alcohol, so does her unborn baby. If you drink alcohol while you are pregnant, you may be at risk of giving birth to a baby with Fetal Alcohol Spectrum disorder (FASD). If you need help to stop drinking, ask your healthcare provider for advice. Tell your partner, family, friends and community members who can all support you with this decision.

When you are pregnant, or planning a pregnancy there is:

  • No safe time to drink alcohol
  • No safe type of alcohol
  • No safe amount of alcohol

Learn more about Alcohol and Pregnancy and Fetal Alcohol Spectrum Disorder.

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Caffeine2 10

Caffeine is a stimulant that can cross the placenta and affect your baby.  Coffee, tea, pop, and energy drinks may have caffeine in them.  Too much caffeine is not good for your unborn baby.

  • It's best not to drink more than two cups (500 ml) of coffee each day
  • Water is the best drink when you are thirsty
  • All energy drinks and some kinds of herbal teas are not safe to drink when you are pregnant or breastfeeding

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Food Safety9 10

Take extra care with food when you are pregnant. Food poisoning can be dangerous when you are pregnant. Both you and your unborn baby can get quite sick if you eat foods infected by bacteria, viruses and parasites during pregnancy.

It is very important that you follow food safety practices for pregnant people and avoid eating foods that are more likely to cause a food borne illness when you are pregnant.

  • Wash your hands before, during, and after you handle food
  • Wash the skin of all raw vegetables and fruit well
  • Cook meat, poultry, seafood, fish, and eggs well
  • Reheat cooked food until steaming hot
  • Check “best before” dates on food packages and do not eat the food after that date has passed
  • Eat leftovers stored in the refrigerator within 3 to 4 days

Avoid these foods when you are pregnant:

  • Unheated hotdogs and deli meats
  • Patés, meat spreads, smoked seafood, and fish products that are not in a can
  • Foods made with raw eggs, or that contain eggs that are not fully cooked
  • Unpasteurized milk and foods made from unpasteurized milk
  • Soft cheeses made from unpasteurized and pasteurized milk such as brie, camembert, feta, goat cheese, queso blanco, and blue cheese
  • Juices that are not pasteurized, such as unpasteurized apple cider
  • Raw sprouts, especially alfalfa sprouts and bean sprouts
  • More than 1 serving (75g) of liver every 2 weeks
  • Undercooked meat, poultry, and seafood
  • Raw fish and food made with raw fish (for example, sushi)
  • Fish liver oil
  • Raw seafood such as oysters and clams
  • Fish that is high in mercury. Learn more about mercury in fish and how to choose fish that is low in mercury more often.

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Your Environment

Exposure to environmental toxins, before or during pregnancy, can put you and your baby at risk for future health problems. It is important to make sure to reduce the environmental health risks in your home, workplace and all the places you spend time before you get pregnant. Contact with toxins may make it hard to get pregnant or may cause complications during pregnancy.6

Home Environments7

Harmful chemicals that stick to dust, fumes from cleaning and renovation products, chemicals in plastics, mercury in fish - all of these can have serious impacts on the health of a child even before birth. The good news is that prospective parents can take some simple steps to reduce risks in the home.

Learn more by downloading the Creating Healthy Home Environments for Kids: Top 5 Tips (PDF) by the Canadian Partnership for Children’s Health & Environment, or watch the YouTube Video.


Radon is a naturally occurring radioactive gas that comes from rock and soil. It can enter homes and other buildings and build up to harmful levels. Being exposed long-term to high levels of radon is the number one cause of lung cancer in non-smokers.

To learn how to reduce your exposure to radon in your home, please visit: Canadian Partnership for Children’s Health and Environment: Radon What Families Can Do.

Drinking Water

Pregnant women and young children are at more risk from exposure to contaminated drinking water. If you drink well water, you should have your well water tested 3 times per year. It’s also important to learn about the health effects of nitrates in well water. If you live in an older home with lead service lines, there are specific recommendations for pregnant women and children under six. Learn more about drinking water in London-Middlesex.

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There are certain health problems that can harm your unborn baby if you get them during pregnancy. The best thing that you can do for you and your baby is to talk to your healthcare provider when planning a pregnancy so that they can advise you on any immunizations you may require and early treatment of any health problems. Below are a few infections to learn about.

Bladder infection
It can hurt your kidneys and cause your baby to be born too soon. Protect yourself and your baby by:

  • Drinking lots of fluids (mostly water and at least 8 glasses a day)
  • Wiping yourself from front to back after using the toilet
  • Going to the toilet as soon as you feel the urge to pass urine, before sex, and after sex

It can make your baby very sick. Protect yourself and your baby.

  • Cook meat well
  • Wash vegetables well
  • Wash your hands and any surfaces that you use to prepare food
  • Do not drink or eat any unpasteurized milk products
  • Avoid cleaning cat litter boxes;  if possible, have someone else change litter boxes
  • Wear gloves if you must change the cat litter box and when gardening; when done, wash your hands

Learn more about Infectious Diseases.

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Medications & Herbal Supplements11

If you are thinking of becoming pregnant or are pregnant it is important to speak with a healthcare provider before taking any type of medication, supplement or herbal product.

Medicines, including over-the-counter drugs, herbal products and supplements are more complex than you may think. Learning which products are safe to take when trying to become pregnant or if you are already pregnant is especially important. Some medications are safe to take and others may pose a risk to your growing baby.  Street drugs are never safe for use, particularly before or during pregnancy.

Ask your healthcare provider the following questions:

  • Is this medication or herbal remedy safe to take if planning a pregnancy?
  • What are the benefits?
  • What are the risks?
  • Are there any alternatives?

The MotherToBaby website is a great resource to learn more about medication use during pregnancy and breastfeeding.

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Smoking12 10

Stopping smoking before pregnancy, or as early as possible in pregnancy, will help you and your baby. Smoking is harmful to pregnant women and their babies. Smoking can cause complications during pregnancy.

Your baby may:

  • Not get enough food or oxygen
  • Be born too soon or too small
  • Die suddenly during pregnancy
  • Be more at risk to die from Sudden Infant Death Syndrome (SIDS)
  • Have health or learning problems

Things that you can do:

  • Try to stop smoking or smoke less often
  • Ask others not to smoke near you while you are pregnant and after the baby is born
  • Make your home and car smoke-free areas
  • Once the baby is home, smoke outside and away from the baby
  • Ask for help to quit smoking or to smoke less

For more information visit:

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It’s important to make sure your work environment is safe during pregnancy. The workplace often has more hazards in it than your home. Follow precautions at work and speak to your healthcare provider to determine what changes you may need to make. For more information, visit:

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Get Help

  • Talk to your healthcare provider
    If you don’t have a primary healthcare provider, learn how to find a doctor.
  • Heartspace
    Heartspace is a program offered by Addictions Services of Thames Valley for women who are pregnant, parenting and substance-involved and their children prenatal to 6 years of age. For more information, call 519-673-3242.
  • Reach Out
    Reach Out is a confidential 24/7 information, support and crisis service for people living with mental health or addictions concerns in Elgin, Oxford, Middlesex and London. Call 519-433-2023 or toll-free 1-866-933-2023 (Elgin, Middlesex, Oxford). Reach Out partners with with the Southwestern First Nation Crisis Team. Referrals for Wellness Checks are available upon request (Aamjiwnaang First Nation, Kettle & Stoney Point First Nation, Chippewas of the Thames First Nation, Munsee-Delaware First Nation). Services available in multiple languages upon request. Mobile crisis support available in certain locations within Elgin, Middlesex and Oxford Counties.
  • Quit Tobacco Resources
    Find resources to help you quit smoking.

Additional Resources

Date of creation: July 30, 2014
Last modified on: November 8, 2019


1The Society of Obstetricians and Gynaecologists of Canada. (n.d.). Cannabis and Pregnancy Don’t Mix. Retrieved from
2Health Canada. (2019).Caffeine and Pregnancy Retrieved from
3The Society of Obstetricians and Gynaecologists of Canada. (2018). Are you pregnant or considering pregnancy? Did you know the use of cannabis may be harmful to your baby? Retrieved from
4Best Start Resource Centre (2017). Risks of Cannabis on Fertility, Pregnancy, Breastfeeding and Parenting. Retrieved from
5Canada FASD Research Network.(2018). Policy Action Paper: Toward a Standard Definition of Fetal Alcohol Spectrum Disorder in Canada Retrieved from
6Best Start Resource Centre. (2019). Health Before Pregnancy Retrieved from
7Canadian Partnership for Children’s Health and Environment. (2011). Creating Health Environments for Kids. Retrieved from
8Canadian Partnership for Children's Health & Environment. (2013). Reduce radon. Retrieved from
10Best Start Resource Centre (2016)A Healthy Start for Baby and Me Retrieved from
11The Society of Obstetricians and Gynaecologists of Canada. (2018) Medications and drugs before pregnancy Retrieved from
12Best Start Resource Centre. (2019). Prenatal Education; Smoking Retrieved from