Does Body Mass Index (BMI) Affect Your Chances of Pregnancy with IVF?
Does Body Mass Index (BMI) Affect Your Chances of Pregnancy with IVF?

Does Body Mass Index (BMI) Affect Your Chances of Pregnancy with IVF?

BMI may influence the chances of having a baby through in vitro fertilization (IVF).

There is ongoing discussion about whether a woman’s BMI affects the outcomes with IVF.

Medscape.com article reported there is still no clear conclusion about whether high BMI impacts assisted reproductive outcomes, because the studies presented had conflicting results. There seems to be a trend developing toward a more concrete conclusion, as only one study found that BMI was not important.

Here is a summary of those study results:

In a study by Dr. James Segars, from the Walter Reed Army Medical Center in Washington DC, participating women underwent a total of 1625 IVF cycles (2002-2010). In terms of egg quality, the morbidly obese and the normal weight ladies had the same results. The percentage of retrieved eggs that underwent maturation was found to be about 72% for the normal-to-morbidly obese subjects (71 to 74%), yet only 66% matured for the underweight women. The most appreciable difference was in the group of ladies that were underweight.

On the positive side, no other significant differences between BMI groups were found in the Segars survey, with regard to the number of oocytes retrieved or the percentage of women who got pregnant (51 vs. 57%). Thus, this research group’s results appeared to show that there was no negative trend, even in morbidly obese women seeking assisted reproduction.

In contrast, in a second study of 4,609 patients having an IVF cycle (2004-2010), Dr. David Ryley and the IVF Group at Beth Israel Deaconess Medical Center found that obese women could have a much lower chance of clinical pregnancy and lower chances of a live birth, following IVF.

In the Ryley study, there were appreciable differences between the BMI weight categories. There was a lower chance of live birth after several cycles, with the results worsening significantly as BMI increased, as is summarized in the table below.

BMI Group Chance of Live Birth
Normal 96%
Overweight 63% (33% lower than normal)
Obese 39% (57% lower than normal)
Morbidly Obese 32% (64% lower than normal)

There would be much more debate if only these two studies contradicted each other. However, a retrospective literature analysis conducted by Egyptian researchers of 10 relevant studies supports the Ryley study results, as this group also found that obese women who underwent IVF and intracytoplasmic injection of sperm (ICSI)  had significantly lower chances for pregnancy and live birth. They also found that cycle cancellation and miscarriage rates for obese women were higher.

As reported in the Medscape article, the president of the Society for Reproductive Endocrinology and Infertility, Dr. Marcelle Cedars, shared that it is still not clear whether the extra weight influences egg quality, the uterine environment, or embryo development. She does support the concept that IVF outcomes are significantly poorer in obese patients, stating that “patients fare better if they are not obese.”

BMI is an issue to be discussed. Because obesity cannot be fixed in a short period of time, it is important for doctors and patients to be aware of this topic. Trying to conceive might just be a longer successful journey. In young women, losing weight before trying to conceive with IVF is a consideration.

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