IVF is a very good fertility treatment with high pregnancy rates. Doctors and patients
are always looking to identify factors which might identify patients with a lower chance for success.
If you are overweight, will this lower your chances for IVF success? Stay tuned, I will
present the results of original InfertilityTV research to help answer this question
On today’s episode, I am discussing the impact of weight on IVF success only. If you are more
interested in the effect of weight on your ability to get pregnant naturally,
then check out this episode.
All of the studies I am going to talk about today use BMI or body mass index to investigate
the impact of weight. Although its not perfect, BMI helps us to control for the fact that taller
people are going to weigh more than shorter people even if they are not overweight. BMI categories
may differ slightly in different countries. A low BMI indicates that a person is underweight.
A high BMI, greater than 25 indicates that a person is overweight. A BMI over 30 is defined as
obese.There are also different classes of obesity for people who have a BMI over 35, 40 and so on.
In 2013, this study was published looking at over 12,000 couples who had IVF in Denmark.
This study concluded that pregnancy rates were lower when female BMI was greater than 25
and an even lower pregnancy rate when both partners had a BMI over 25.
This was a nice study. Applying that today however is difficult for two reasons.
First, they looked at couples undergoing a fresh embryo transfer only which is not
done very commonly anymore and second, they didn’t provide information on couples with
higher BMIs such as those greater than 30 or 40 which is much more common today.
If increasing weight lowers the chance for IVF success,
is it due to an effect on the eggs? Or is it an effect on the uterus or some other factor about
the person attempting to carry the pregnancy. A few years later, this study was published
using the IVF registry in the USA. This study looked at patients attempting pregnancy using
donor eggs. By using embryos from higher quality donated eggs, this kind of study is helpful
because it controls for the egg factor. This study also looked at people who had much higher BMIs
in the 40, 45 and 50 range. They concluded that compared with people with normal range BMIs,
those with higher BMIs had lower pregnancy rates and higher miscarriage rates. This
also gives us some idea about couples doing frozen embryo transfers since the method used
to prepare the uterus is donor egg recipients is similar to what we use for frozen embryos
There haven’t been any good studies which looked at the effect of weight on the chance
for pregnancy specifically with frozen embryo transfer. We decided to do that study. This study
was conducted at the Naperville Fertility Center from January until Mid August 2021.
During that time, I performed 310 frozen embryo transfers. To prevent skewing the results,
we analyzed only the first transfer for each patient.This left us with 253 transfers to
analyze. All patients had transfer of a single blastocyst embryo. When we looked
at the percentage of patients who had a positive pregnancy test we saw a definite decline as the
BMI increased. This ranged from 89% in the lowest BMI group to 60% in those with a BMI over 40. Some
patients miscarried after their positive pregnancy test. To look at the percentage of ongoing
pregnancies, we looked at how many patients made it to the point where we were able to see
a fetus with heart motion on ultrasound twice a week apart. This is a pretty good indicator
for those patients who will go on to deliver a baby. We found a lower ongoing pregnancy rate in
patients with a BMI over 30 and a much lower rate, only 20% in patients with a BMI of 40 and over.
We also looked at those patients who used embryos that were tested for chromosome abnormalities.
By transferring only normal embryos we eliminate the impact of age
since younger and older patients have the same pregnancy rate when using normal embryos.
As you can see, pregnancy rates still declined in patients as their BMI became higher.
Our InfertilityTV Bottom line is this. Even when using state of the art IVF techniques
such as frozen embryo transfer, blastocyst transfer and chromosomally normal embryos.
There is still a significant and progressive impact of BMI. The higher the BMI the lower the
chance that an embryo will implant and the lower the chance that a patient will have a delivery.
Patient’s should be aware that IVF does not overcome these problems
Hi! I’m Doctor Randy Morris. I’m an IVF expert in the United States, near Chicago and the host
of Youtube's most popular and informative channel about trying to conceive - InfertilityTV. I give
honest, science based tips that have helped people all over the world have their rainbow baby. If you
want to improve your odds for success,
hit that subscribe button right now. It's like having a fertility specialist in your phone.