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“Hi Vanessa, thanks so much for the informative podcast! I was wondering if it is safe to use a microwave during pregnancy? Both to eat food or drink drinks that are heated in the microwave as well as to stand near the microwave.” – Bianca

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How Microwaves Work

Microwave ovens create electromagnetic waves of energy, aptly called microwaves. Microwaves fall on the spectrum in between radio waves, which are longer, and infared waves, which are shorter. These waves are electromagnetic and they heat food by radiation. They basically excite and vibrate the water molecules in food, which creates friction, which results in heat.

The inside of a microwave oven is made of metal, which helps to reflect the waves. The door of a microwave oven has a thin metal mesh with holes small enough so that the electromagnetic rays cannot escape, but light can so you can see inside. It may seem strange that there is metal inside the microwave because we know you cannot put metal in a microwave. This is because metal reflects the electromagnetic waves and can act as an antenna and it can magnify the temperature so that the high temperatures in the oven can cause it to explode or damage the parts.

Microwaves only penetrate about 1 cm into foods. Which is why foods can heat unevenly. It can seem like microwaved food cooks from the inside out, but it is actually the opposite. The plate that spins in the oven rotates your food to help it heat more evenly. The uneven heating is one of the reasons that microwaving is not ideal for reheating breast milk or heating baby formula. It can create hotspots that can burn your baby, and it can be heated too hot. When you warm a bottle for your baby you want to let the bottle sit in hot or warm water to heat it up.

The Safety of Microwaves

Many countries and international organizations have set standards for the limits on emissions from the outside of the oven. The most widely used limit is 50 watts per square meter at any point 5 cm away from the surface of the oven. Microwaves sold should be well below this limit. Plus, distance decreases exposure. If you are 50 cm away you receive about one hundredth of the exposure than if you are standing 5 cm away.

Microwave ovens are engineered to protect you from electromagnetic waves. This is done by the design of the metal interior, the screen on the door, and a safety which shuts it off when the door is opened. For more information on international regulations and the World Health Organization click here.

Safety Requirements from the FDA

The FDA requires all ovens to have two independent interlock systems that stop the production of microwaves the moment the latch is released or the door is opened. In addition, a monitoring system stops oven operation in case one or both of the interlock systems fail. The FDA recommends looking at your oven carefully, and not using an oven if the door doesn’t close firmly or is bent, warped, or otherwise damaged. If the door hinges, latch, or seals are damaged it is time to get rid of your microwave and buy a new one.

The FDA tests microwave ovens in their own laboratory to ensure they meet safety standards. The FDA also evaluates manufacturers’ radiation testing and quality control programs at their factories. If you would like to see the full guidelines from the FDA on microwave oven radiation you can click here.

When thinking about the safety of microwaves, keep in mind that these waves are not just used for heating food. Other commonly used devices, like cell phones, blue tooth, and even baby monitors emit microwaves. There has been concerns raised in recent years about EMF (electro magnetic field) exposure and that topic is beyond the scope of this episode but it will be visited in the future.

It is safe to use a microwave that works properly. This assumes it is not damaged and operates how it is supposed to. Waves disappear as soon as the oven is turned off by the timer ending, a manual cancellation, or the door opening. The waves do not remain in your food and your food is not radioactive. If you are concerned about the microwaves being emitted while the appliance is on don’t stand directly in front of it. You can step a few feet away or even leave the room and you would be minimizing any potential exposure.

Is it Better to Use an Oven or Stove?

Compared to other methods, does the process of cooking food in a microwave make food less healthy. Many people would argue that food tastes better when cooked in a conventional oven or on the stove, and I would personally have to agree. In some cases using a microwave can preserve nutrients. Spinach retains 70% more folate when you cook it in a microwave compared to boiling it on the stove. Whether cooking by other methods are better is largely up to your preference, and how much time you have to prepare meals. No doubt microwaves are a convenience that speed up the time it takes to prepare a meal.

The majority of foods marketed as microwavable, like frozen dinners, are not going to be the ideal diet for anyone, especially if you are pregnant. When you are pregnant you should be eating healthy whole foods, not prepackaged frozen microwavable meals. These often contain a lot of preservatives and are high in sugar and sodium. Using healthy whole food ingredients is much more important than how you cook your food.


Thank you to the amazing companies that have supported this episode.

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Zahler makes a high quality prenatal vitamin that has the active form of folate plus omega 3s and DHA. This is my favorite prenatal vitamin, the one I take everyday and the one I recommend to all expecting moms. Zahler is offering an exclusive discount to listeners of the Pregnancy Podcast. To check out the vitamin and find out how you can save 25% when you buy a one month supply on Amazon click this link Zahler Prenatal + DHA.