Why Is There A BMI Limit For IVF?

1. What is BMI?
2. Required BMI for IVF
3. What is the best BMI for IVF?
4. What if my BMI is not ideal for IVF?
5. Is it possible to get pregnant with a high BMI?

Each of these women is individual not only in terms of their reproductive problem, but also in terms of baseline data, such as body mass index (BMI). Is there a weight limit for IVF? Formally, no, but before accepting you into the program, doctors are required to warn you about all the risks associated with violating the weight limit for IVF. If your BMI is very different from normal, you will most likely be offered to lose or gain weight.

We regularly blog about preparing for IVF, including tips on weight normalization, treatment of chronic diseases, and more. None of the tips is a magic pill that can make you pregnant. But following them significantly increases your chances of getting pregnant.

In this material, we will look at what BMI is, BMI requirements for IVF, find out the optimal IVF BMI limits, and also study risk factors for women with low and high BMI.

What is BMI?

Body mass index (BMI) is the ratio of a person's weight to his height squared. The indicator reflects the amount of fat in the body and is taken into account when creating BMI requirements for IVF. However, it should be noted that this parameter has a limitation in use: people with high muscle mass, such as athletes, should not take BMI into account when undergoing IVF treatment.

Formula for calculating BMI: weight/height*height. That is, for a person weighing 65 kg and height 170 cm, BMI = 65/1.7*1.7 = 22.5                                                                                                                                                                                                                                                     

Normal indicators for men and women:

• less than 19 – underweight;
• 19-24 - normal;
• 25-29 - overweight;
• more than 30 – obesity.

There are no weight requirements for IVF. However, both underweight and excess body weight negatively affect fertility. Therefore, both low and high BMI during IVF treatment can reduce the effectiveness of the procedure.

Required BMI for IVF

BMI for IVF does not play a decisive role: women of all shapes and sizes have a chance to achieve pregnancy and safely give birth to a healthy child. Therefore, BMI during IVF is taken into account only in conjunction with other factors that are important for the success of the procedure:

1. Age.
2. State of the reproductive system.
3. Hormonal status.

Weight limits for IVFis considered rather in terms of the influence of adipose tissue as a source of additional estrogen on the general hormonal background of a woman.

Estrogen determines weight and fertility. The hormone is produced by the ovaries, adrenal glands and adipose tissue. Accordingly, the higher the BMI, the higher the estrogen level. In turn, the more estrogen in the body, the thicker the endometrium of the uterus in preparation for pregnancy. Excessive concentrations of the hormone can disrupt the menstrual cycle, and in more serious cases, ovulation may stop.

Low BMI also negatively affects fertility. When there is a lack of nutrients produced by adipose tissue, the body experiences stress, which can lead to the shutdown of secondary systems, such as the reproductive system. Hormonal balance is disrupted, which manifests itself in an irregular cycle or absence of menstruation.

The American Society for Reproductive Medicine (ASRM) has evidence that a higher percentage of body fat may determine the success of IVF, which is why many reproductive medicine specialists insist on bringing weight to the optimal limit for IVF.

What is the best BMI for IVF?

Many fertility clinics have a weight limit for IVF between around 19-30. The decision on admission to the program is made by the attending physician individually for each patient, taking into account his medical history.

The exact nature of the relationship between a woman’s body weight and her fertility has not yet been established. However, the negative impact of obesity on the success of IVF is quite obvious. The study found that women with a high BMI had more miscarriages and an overall lower live birth rate. There was also a tendency towards a decrease in the number of mature eggs and embryos that reached the blastocyst stage.

Another study found the effect of high BMI on endometrial receptivity in women undergoing IVF. Obesity had a negative impact on the success of IVF by shifting the implantation window - the time when the endometrium is most receptive and ready to accept an embryo.

Thus, the weight limit for IVF is dictated by the desire of doctors to maximize your chances of a successful pregnancy and the birth of a healthy child.

What if my BMI is not ideal for IVF?

If your weight is not within the IVF BMI limits established in the clinic, your attending physician will most likely recommend reducing your weight by 5-10%. In addition to the standard recommendation for weight loss, a good clinic will offer you a consultation with an endocrinologist, because not in all cases weight loss can solve the problem. In some cases, polycystic ovary syndrome may be the cause of weight gain.

Lack of weight is also a reason to consult a specialist and develop a weight gain program.

In addition to working with body weight, controlling hormone levels, in particular anti-Müllerian hormone (AMH), will help increase the chances of successful IVF. This simple technique will help your healthcare provider determine your fertility and how your BMI may affect your ability to achieve pregnancy.

Is it possible to get pregnant with a high BMI?

Yes, as noted earlier, women of all shapes and sizes have a chance of pregnancy and successful birth of a child. Any assisted reproductive technologies are at your service, including egg donor services. However, if your BMI exceeds the limit for IVF, you may face many problems at all stages of the reproductive program: from stimulating ovulation and retrieving oocytes to pregnancy and delivery.

In women whose BMI exceeds 30, the risk of miscarriage in the first trimester is significantly increased; gestational diabetes, hypertension and preeclampsia are more common during pregnancy.

It is also quite significant that, in the absence of other disorders, 80% of women who lost at least 10% weight experienced improved fertility without treatment.

If you are worried that your BMI may become an obstacle to pregnancy and a long-awaited baby, do not self-medicate, especially do not practice the “eat apples and water until the weight drops” diet. Order a free consultation with our endocrinologist from the manager on the website and receive professional recommendations.