Why is BMI Important When Becoming a Surrogate?

One of our most asked surrogate questions is “why does BMI matter for becoming a surrogate?” We understand the frustration and confusion around the subject. This question has only become more prevalent in recent years, as BMI has been analyzed by many doctors, nutritionists, and scientists to gauge the accuracy of the measurement for judging health. We have broken down the ins and outs of BMI and why it is still an important measurement when discussing pregnancy, surrogacy, and the health related risks associated with being pregnant.

Here are a few of our most asked questions surrounding weight and body mass index:

What is BMI?

The National Heart, Lung, and Blood Institute explains that body mass index or BMI is a useful measure of overweight and obesity. It is calculated from your height and weight. BMI is an estimate of body fat and a good gauge of your risk for diseases that can occur with more body fat. You can learn more about our surrogate qualifications and calculate your body mass index here!

“I’m athletically built but have a high body mass index.  My doctor confirms I’m healthy and that BMI isn’t a true indicator of overall health. Is this true?”

There have been many scientific studies in the past 5 to 10 years to determine the validity of using body mass index to measure overall health. BMI does have limitations. It may overestimate body fat in athletes and others who have a more muscular build, and it may underestimate body fat in older persons and others who have lost muscle. According to Dr. Alessandro Demaio, “While it’s a simple and useful screening tool when looking at groups of people, it’s not an accurate marker of individual health.”

Based on recent research and evidence, BMI is not a true indicator of overall health, but is still an important measurement for certain fertility treatments that work optimally on women with a BMI between 18.5-24.9. 

At Circle, we accept surrogates with body mass indexes up to 33!

“My BMI is over 33, but I had no trouble getting pregnant myself. My babies were healthy with no complications.”

Healthy PregnancyThe process of getting pregnant naturally is very different than an IVF pregnancy. When becoming a gestational surrogate, a created embryo is implanted in the uterus and fertility medications are used to aid in the implantation of the embryos. The medications used in this process work optimally with women within a specific body mass index range. Health Magazine recently published and article explaining why BMI may impact IVF success and the role that weight plays in IVF pregnancy.

According to Christine Greves, MD, an ob-gyn with Orlando Health System in Florida, “obesity can complicate IVF.” A study published in August 2018 in the Journal of Assisted Reproduction and Genetics found that women with a BMI above the normal range had a higher risk for IVF cycle cancellation  and lower rates of ongoing pregnancy.

“Even with a higher BMI, I can still get pregnant as a surrogate. Why does it matter?”

A surrogate must have a body mass index of 33 or below. Class II Obesity, a BMI above 35, can increase the time to conception two-fold. Additionally, underweight women with a BMI less than 19 can take up to four times longer to conceive. There are also associated risks that come with having a higher BMI during pregnancy. According to Peter Kovacs, MD, PhD , “Women in obese class I and obese class II-III had lower clinical pregnancy rates compared with normal weight women.” These women may be at a higher risk for gestational diabetes, preeclampsia, and other pregnancy related conditions.

When it comes to surrogacy, an extended time to conception means time, money, and emotional expenditure for both the intended parents and surrogate. Screening gestational carriers for BMI’s under 33 can help to avoid any potential complications with the in-vitro fertilization process. Our goal is to create the safest scenario for our surrogates and the highest rate of a successful outcome for our intended parents.


For more information on our surrogate requirements and why we have them, check out our recent blog post or visit our surrogate qualifications page. If you’re interested in becoming a surrogate with Circle, we encourage you to apply!