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BMI Requirements for Surrogacy – A Complete Guide for Surrogates

The topic of BMI (Body Mass Index) has been a hot button issue for a long time in the world of IVF and surrogacy, sparking debates and discussions among intended parents, surrogates, and medical professionals alike. As surrogacy becomes increasingly popular, BMI requirements have become a focal point due to their potential implications for both the surrogate’s health and the success of the pregnancy.

While some agencies and clinics enforce strict BMI cutoffs to mitigate health risks and optimize pregnancy outcomes, others argue that such criteria may exclude otherwise suitable candidates or perpetuate biases against individuals with higher BMIs. Balancing the health and safety of all parties involved while promoting inclusivity and fairness remains a central challenge in navigating the evolving landscape of surrogacy.

Some Surrogate Applicants Can Feel Anger About the BMI Requirements

Becoming a gestational carrier is a big decision that can dramatically change the life of a person or couple wanting to become parents. Despite the tremendous need for surrogates, though, not everyone is eligible, as surrogates must satisfy a range of health requirements in order to ensure the safety of themselves and the child they carry.

Of all the surrogate requirements, BMI is often one of the biggest challenges that women face. This can be frustrating for the women who want to help others bring a new life into their families. Many of the women who are disqualified because of BMI say that this metric of measuring health is outdated and doesn’t apply to everyone. They often also argue that their previous pregnancies were uncomplicated and they delivered healthy babies, so therefore their weight shouldn’t be a factor.

For all the opponents of the BMI requirement, I’m here to tell you that there are reasons behind this strict requirement. I know this is an unpopular statement to make, but I still encourage you to keep reading and learn more about the medical argument for BMI requirements.

What Is BMI?

Body mass index (BMI) is a measurement of someone’s body fat based on their height and weight.

To calculate your BMI, you simply divide your weight in kilograms by your height (in meters) squared.

Since the United States uses the Imperial measurement system, we have an added step of first converting our height and weight into their metric equivalents (meters and kilograms) before completing the calculations.

To make this easier, many BMI calculators are available, including one from the National Heart, Lung, and Blood Institute. With these calculators you only need to put in your height and weight, and they take over with the conversions and mathematical operations.

Once you have your BMI, it will fall into one of the four following categories:

  • Underweight: <18.5
  • Normal Weight: 18.5 – 24.9
  • Overweight: 25 – 29.9
  • Obesity: 30+

BMI Requirements for Surrogates in the United States

The standard BMI requirement for a gestational carrier is 19-32, although some rare clinics may allow up to 35 BMI. These numbers are set by the fertility clinics who follow the ASRM (American Society for Reproductive Medicine) guidelines. This narrows the range at which someone can qualify as a gestational carrier, but why is this requirement in place? The short answer is to protect both the surrogate and the baby, but let’s take a closer look at how.

The Health Risks to A Surrogate with A High BMI

With surrogacy, the intended parents are looking for someone with the highest possible chances of a successful pregnancy. Since weight is a contributing factor in how safely and successfully someone can give birth to a child, BMI requirements are in place.

Those with a high BMI are at a higher risk of many complications during pregnancy, some beginning immediately in the surrogacy journey. For instance, those who are overweight often have a hard time becoming pregnant, with research showing that, on average, it takes a woman with a BMI over 35 twice as long to get pregnant because of the inhibition of regular ovulation.

There is also a higher risk of complications during pregnancy, such as gestational diabetes, which is the most common complication associated with obesity during pregnancy. Gestational diabetes then comes with associated complications, including gestational hypertension and preeclampsia. These not only affect you, as the surrogate, but can also impact the child you are carrying.

Additionally, women with hyperglycemia (high blood sugar) while the fetus is developing their organs have a higher risk of miscarriage and congenital abnormalities. Those with a high BMI are at risk of other complications as well, including venous thromboembolism, with research showing that up to 57% of those who die from this complication fall within the obese BMI range.

As for labor and delivery, a high BMI correlates to a higher risk of slower labor progression and fetal distress. There is also a higher risk of anesthesia-related complications.

All of these potential complications emphasize that those with a high BMI are at risk of a more dangerous pregnancy. With the safety of the surrogate as a primary concern, BMI requirements are crucial for ensuring a safe pregnancy.

How A Surrogate’s High BMI Affects the Baby’s Health

In addition to the surrogate, a high BMI is also associated with health risks to the baby they are carrying. Various factors contribute to these health risks, with some research showing that inflammation, increased insulin resistance, and oxidative stress in the surrogate can result in early placental and fetal dysfunction. Studies have also shown a higher incidence of miscarriage and stillbirth in those with a high BMI.

Children carried by women with a high BMI are also shown to have a higher incidence of congenital anomalies such as omphalocele, spina bifida, and cardiac defects.

Yet another way in which babies may be affected by a surrogate with a high BMI is through macrosomia, which means they are a large size for their gestational age. This then increases the risk of poor delivery outcomes and traumatic injuries sustained by both the infant and surrogate.

These risks show the importance of a surrogate being within the required BMI guidelines to ensure that the child they carry is in the best possible health.

Is BMI An Outdated Health Measure?

Many have claimed that BMI is an outdated measure of health since it does not account for different body compositions or other factors such as age, race, gender, genetics, muscle mass, fat mass, or bone density. 

While these facts may be true, when it comes to gestational carriers, research has shown that BMI has some vital bearing. In fact, research involving fertility sciences shows that a normal pregnancy often falls within a specific BMI range, which is why surrogates must fall within this range.

Part of the reason why BMI remains a good health indicator is that being above normal weight is considered a risk factor for many conditions, such as diabetes, heart disease, and pregnancy complications. While BMI is only a general indicator, it remains a good identifier of who is at greater risk.

The Importance of BMI in Surrogacy

A lot about pregnancy cannot be controlled, which can be overwhelming for those seeking a surrogate. However, having specific requirements for surrogates, including BMI, is one thing that can be regulated to promote a healthier and more successful experience. 

With the ample evidence showing the potential risks faced by women with a high BMI during pregnancy, both to them and the child they carry, setting a requirement is one way that fertility clinics can ensure that the pregnancies they help with are safe for all involved.

While it can be disappointing to not meet the BMI requirements of surrogates, the risks associated with a high BMI are real and costly to you, the baby, and the intended parents. Still, don’t be dissuaded from being a surrogate if your BMI is too high. Instead, take the time to focus on a balanced diet, increase your activity levels, and lose weight beforehand to lower your BMI and ensure a smoother pregnancy. In the end, you’ll find that you also reduce the risk of many health complications for yourself unrelated to pregnancy.

Above all else, remember that these guidelines, based on scientific evidence, are in place to protect both you and the baby. They may be frustrating for some, but they’re preferable to the alternative. 

Medical References

Calculate Your BMI – Standard BMI Calculator. (2023). https://www.nhlbi.nih.gov/health/educational/lose_wt/BMI/bmicalc.htm

Couples with obesity may take longer to achieve pregnancy, NIH study suggests. (2017). https://www.nichd.nih.gov/newsroom/releases/020217-couple-obesity

Ozcan Dag, Z., & Dilbaz, B. (2015). Impact of obesity on infertility in women. Journal Of The Turkish German Gynecological Association, 16(2), 111-117. doi: 10.5152/jtgga.2015.15232

Kim J, Ayabe A. Obesity In Pregnancy. [Updated 2022 Aug 8]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK572113/#

Lyons G. (2008). Saving mothers’ lives: confidential enquiry into maternal and child health 2003-5. International journal of obstetric anesthesia, 17(2), 103–105. https://doi.org/10.1016/j.ijoa.2008.01.006

Taylor, C. R., Dominguez, J. E., & Habib, A. S. (2019). Obesity And Obstetric Anesthesia: Current Insights. Local and regional anesthesia, 12, 111–124. https://doi.org/10.2147/LRA.S186530

Catalano, P. M., & Shankar, K. (2017). Obesity and pregnancy: mechanisms of short term and long term adverse consequences for mother and child. BMJ (Clinical research ed.), 356, j1. https://doi.org/10.1136/bmj.j1

Lashen, H., Fear, K., & Sturdee, D. W. (2004). Obesity is associated with increased risk of first trimester and recurrent miscarriage: matched case-control study. Human reproduction (Oxford, England), 19(7), 1644–1646. https://doi.org/10.1093/humrep/deh277

Anderson, J. L., Waller, D. K., Canfield, M. A., Shaw, G. M., Watkins, M. L., & Werler, M. M. (2005). Maternal obesity, gestational diabetes, and central nervous system birth defects. Epidemiology (Cambridge, Mass.), 16(1), 87–92. https://doi.org/10.1097/01.ede.0000147122.97061.bb

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