How BMI Affects Surrogacy Candidacy

BMI affects surrogacy

BMI, also known as Body Mass Index, is a rating system that is used to provide an overview of a person’s weight in relation to their height. Generally, a person is considered to be at a healthy weight when their BMI falls between 18.5 and 24.9. Lower than this usually means the person is underweight. While a BMI of 25 or higher means the individual has too much body fat. 

When it comes to surrogacy, BMI is used as a tool to help a clinic assess a person’s health and consider if weight might pose a problem during pregnancy. Several studies have confirmed that women who are underweight, as well as those with too much body fat, are at risk of certain complications when they do become pregnant.

In this blog, we will take a closer look at the relation between BMI and becoming a Surrogate mother. We will discuss how a low BMI (a person who is underweight)  could have a negative effect during pregnancy. Additionally, we will also consider how excess fat in the female body might cause problems. 

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Understanding How BMI Works

As we have mentioned already, BMI stands for Body Mass Index and essentially provides an overview of the relation between body weight and height. The Academy of Nutrition and Dietetics explains that BMI is primarily used as an indication of how much body fat a person has. While this is not the only tool that is used to provide an indication of a person’s overall health, it can offer a physician a good view of the chances for a successful pregnancy. 

The following are the general guidelines used to explain what a person’s BMI means:

  • BMI that is lower than 18.5 = underweight
  • BMI that is between 18.5 and 24.9 = normal weight
  • BMI that is between 25.0 and 29.9 = overweight
  • BMI that is over 30.0 = obese

When a person has a BMI that indicates they are underweight, it usually means they are not obtaining an adequate amount of calories on a daily basis. On the other hand, when the BMI is too high, the number of calories consumed may be too much. 

How A Low BMI Affects Pregnancy

A woman who has a BMI that indicates she is underweight may be at risk of certain complications that need to be taken into account when considering potential surrogates.  The primary risk that is associated with a low BMI is preterm birth. There is also a risk of a Small Gestational Age Baby. When these complications occur during pregnancy, this puts the baby at risk of certain health problems.  – and without adequate treatment, the baby’s life may also be in danger. 

How A High BMI Affects Pregnancy

Women who have a high BMI are also at risk of several complications during pregnancy. Additionally, a high BMI might be an indication that certain problems could occur with a woman’s fertility.  This could make it more difficult for a successful pregnancy during a procedure such as IVF. 

A review paper published in the Journal of the Turkish-German Gynecological Association explains that obesity has a significant negative impact on fertility. The paper explains that studies found infertility to be especially high among obese women. Infertility is not the only concern that is mentioned here. 

According to the researchers behind this particular publication, there are several other factors that need to be taken into account when women with a high BMI want to become pregnant. Reproductive outcomes in the form of difficulty getting pregnant, as well as actual complications that can occur while pregnant, are both concerns that need to be taken into consideration. 

The Office on Women’s Health explains that a high BMI has been found to prevent ovulation. This makes it harder for sperm to attach to the egg of a woman. Additionally, a high BMI also seems to interfere with the effectiveness of fertility treatments. 

Some of the risks that have been noted among pregnant women with a high BMI  include:

  • Gestational diabetes, where diabetes develops during pregnancy. This can increase a woman’s risk of developing type 2 diabetes. When gestational diabetes occurs, low blood sugar may develop in the unborn baby. In turn, the woman and the baby are at risk of certain complications. 
  • Women with a high BMI are more likely to experience complications during childbirth, which often calls for the need to have a C-section done. 
  • Gestational hypertension is another risk to be taken into consideration. This is when hypertension, or high blood pressure, develops while the woman is pregnant. There is a serious complication that may result from gestational hypertension, known as preeclampsia. 

What Is The Ideal BMI For Surrogates?

While we often hear that women will be eating for two while they are pregnant and that weight gain is normal during this time, it is important to take a step back and consider what the most ideal BMI would be for a surrogate. 

There are a variety of requirements that a woman must meet before they are accepted into a program. Having a BMI within a normal range is one of them.  

A normal BMI means the woman should have a rating that falls between 18.5 and 24.9. It is sometimes advised that having a BMI that is slightly higher than 24.9, which would make the woman overweight, is not bad either. Weight gain is closely monitored during pregnancy. Too much weight gain can cause problems during a pregnancy endangering both the surrogate and the baby.

What Happens When The BMI Of A Potential Surrogate Mother Is Not In The Ideal Range?

Typically, the physician overseeing the surrogate’s pregnancy will provide a recommendation on the amount of weight that should ideally be gained. While there is a general recommendation that women who start off their pregnancy at a healthy weight gain approximately 25 pounds, with a maximum of 35 pounds advised. This may be different for a person with a BMI that is not in the normal weight range.

When a woman has a BMI that indicates she is underweight, the recommendation would usually be between 28 pounds and 40 pounds. This weight should be gained in a healthy way. Calories are often increased without causing the woman to start following unhealthy eating habits. Instead, a special diet can be developed that ensures the calories consumed – including the extra ones – come from food that is able to provide both the woman and the baby with adequate nutrients. 

If a woman has a BMI that is too high, then her physician might advise that she loses some weight before she becomes pregnant through artificial insemination or IVF. This is to assist in reducing the risks that are associated with a high BMI during pregnancy. A specialized plan can also be developed in this case.  A healthy diet would be provided to the woman, along with an exercise plan. The nutrition in the food consumed will not only assist with improving weight management but also help prepare the woman’s body for pregnancy – thus ensuring once pregnant, there will be adequate nutrients for the baby as well. 

Overweight women who do get pregnant are advised not to gain more than 20 to 25 pounds during pregnancy, depending on their weight at the start of the pregnancy.  When the person has a high BMI, the maximum amount of weight to be gained during pregnancy is 25 pounds. 


There is a strong relationship between a woman’s BMI and her chances of being an ideal candidate as a surrogate. Having a BMI that is either too low or too high can be problematic during pregnancy. This rating is often utilized by physicians when they assess the general well-being of a woman who is planning on becoming a surrogate. Fortunately, when a woman’s BMI is not ideal for pregnancy, there are steps that can be taken to provide an improvement in her weight management. 

Physician’s Surrogacy, a surrogacy agency in San Diego, has helped form over 1,000 families. As experts in the field of surrogacy, Physician’s Surrogacy is armed with more than 100 years of combined experience and provides you with a fully integrated solution. We stand by your side during your entire surrogacy journey. Visit us or call (858) 299-4580 to learn more about the surrogacy process. 

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Looking for Reliable Surrogacy Info?

Physician’s Surrogacy is the nation’s only physician-managed surrogacy agency. Join our community to get updates on surrogacy, expert insights, free resources and more.