BMI and Fertility: Understanding Your Options
The topic of weight and fertility is a sensitive one, and one that we take very seriously. First off: women of all shapes and sizes can have healthy pregnancies. However, in pregnancy and while undergoing fertility treatments, a high BMI can pose safety concerns to both the woman and fetus. The reasons for this, and the options available for those with a high BMI, are described below.
What is BMI?
Body Mass Index (BMI) is a measure of the ratio of a person’s weight to their height. If someone has a larger mass and/or a shorter height, this tends to result in a higher BMI value.
Here's how Health Canada categories BMI:
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BMI Range
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Category
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< 18.5
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Underweight
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18.5 – 24.9
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Average Weight
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25.0 – 29.9
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Overweight
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30.0 – 34.9
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Obese I
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35.0 – 39.9
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Obese II
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≥40.0
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Obese III
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Health Canada (2021)
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Doctors use BMI when assessing risk for a variety of health conditions, such as diabetes, high blood pressure and heart health. They also use BMI when assessing a person’s fertility health. It’s important to note that while a high BMI can place people at risk of some health complications – so can a low BMI. For example, anemia, osteoporosis and vitamin deficiency tend to occur more often in those with a low BMI.
Keep in mind: BMI is not simply a measure of fat. Those with a very high muscle mass (such as bodybuilders) can have a high BMI. Moreover, BMI is not only impacted by what we eat and how much we exercise. Genetics and ethnicity – both things we can’t control – can also influence how our body stores and metabolizes fat.
How does BMI impact fertility?
Research suggests that BMI impacts fertility health in both men (or those AMAB) and women (or those AFAB). Those with a high BMI may have a harder time achieving a successful pregnancy due to a number of factors, including:
- Decreased chance of concieving per cycle
- Increased likelihood of needing fertility care
- Higher risk of pregnancy loss
- Fewer follicles/oocytes per fertility treatment cycle
- Challenges with accessing the ovaries during egg retrieval
- Lower sperm count and poor semen parameters
- Erectile dysfunction
Keep in mind: Not all people with a higher BMI will experience fertility health issues. A healthy pregnancy is still very possible! However, your fertility team will keep these risks and challenges in mind when discussing your fertility options.
Will a high BMI limit my access to fertility care?
The primary concern of any medical practice is patient safety: a doctor has a duty to their patients to provide safe, effective treatment and minimize risk of complications. Since a higher BMI may put a woman at risk of potentially serious consequences, many clinics have guidelines in place on the use of fertility procedures in those with a high BMI. Let’s discuss this further.
Safety during sedation
The College of Physicians and Surgeons (CPSO), which is the regulatory body for physicians in Canada, has guidelines for the safe administration of sedation (anaesthesia) during IVF procedures performed outside of a hosiptal setting. This is why many clinics have a BMI “cut-off” (typically BMI ≥40) above which they cannot offer sedation during an egg retrieval. In these cases, less effective oral sedation techniques or supervision of anesthesia by an anesthesiologist is needed, which is not routinley available in a fertility clinic setting. This could limit a person’s access to IVF – which may be their most effective fertility treatment – until their BMI is below the threshold of the CPSO guidelines.
Risk of complications
As BMI increases, the overall risk of maternal or fetal complications also increases, which clinics must be mindful of. Many clinics have a policy that above a certain BMI, the health risks are too significant to proceed with fertility treatments. In these cases, the first step of a person’s fertility journey would be working to reduce BMI to mitigate the risk of complications. In fact, with significant lifestyle changes, pregnancy may be possible without any interventions.
If you have a high BMI, what does your fertility journey look like?
We understand that being denied a treatment you very much want can be extremely difficult, and trigger feelings of shame, sadness or even anger. Know that if this happens to you, it is not a judgment of your weight or lifestyle – it is a decision made to ensure your safety. Also know that your fertility journey does not have to end here. If you wish, your fertility team will put a plan in place to help you safely lower your BMI so that you can achieve your family-building dreams.
At Generation Fertility, we support patients along their entire fertility journey, especially if weight loss and other lifestyle modifications are part of the advised treatment plan. We work with a fertility-focused dietician and other healthcare providers to help our patients achieve their goals in a healthy and sustainable way. Weight loss is not an easy process, and there is no shame in requiring a little extra help to help you get there. We’re here for you – and will guide you with empathy, encouragement and professionalism every step of the way.
