Marie, I’m a future mother and am 26 weeks pregnant. I am distraught because my doctor told me I’m gaining too much weight. I have to admit that shook me up because I am eating well and walk 2-3 times a week. I don’t know what to think. He told me my BMI was limit at the start of my pregnancy, but I don’t know what he was referring to. Can you help me?

Thank you for everything you do for parents!

Hello Madeleine,
Your question is very important. What is BMI? BMI refers to body-mass index. It’s an international mathematical formula to calculate a person’s weight based on their height to determine if they are within recommended health standards. If the result of the BMI calculation is too low, the person is too thin. On the contrary, if the result is too high, the person is overweight or even obese. 

Madeleine, it’s normal to gain weight during pregnancy, even if a woman was overweight at the start. However, your health professional will regularly verify it to prevent risks associated with being overweight. For a pregnant woman, this could be high blood pressure or gestational diabetes for example.

You already have good eating habits and lifestyle due to your exercise, sleep, etc. You can be confident that everything is fine and the weight you have already gained will stabilise over the coming weeks. Some pregnant women are more predisposed to retaining water, swelling, oedema, and this water is very heavy on a scale. In this sense, you have not gained fat but mostly water. I don’t know the details of your condition, so I would suggest you talk to your doctor about your concerns. They can then examine you to evaluate your situation. They have all the data they need to do this.

I don’t know if you feel like doing it, but to better understand BMI, I added the formula to calculate BMI and a link to an online BMI calculator. Very easy to use! However, you should know that you should calculate your BMI with your weight before or at the start of your pregnancy and not with your current weight. Pregnancy is not part of BMI calculation parameters.

BMI takes into account the person’s weight in kilograms and height in centimetres. This index was designed for adults 18-65 because other age groups have specific considerations which do not fit into the general calculation. This includes children, seniors and pregnant women.

BMI = Weight (kg)  / Height (m) 2

Normal BMI is between 18.5 and 24.9 kg/m2. Thinness is under 18.5, and overweight is above 24.9. Obesity is a BMI score of 30 or more, and morbid obesity is above 40.

There you go, Madeleine. I hope you better understand BMI and can direct your questions with your health professional during your next pregnancy monitoring appointment. All the best!


To learn more about BMI, you can read:


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