in vitro fertilization

Researchers examine whether a higher body mass index (BMI) in women with endometriosis improves the chances of success after in vitro fertilization.

It is known that overweight and obese women have a lower chance of pregnancy following in vitro fertilization.1 It is also known that women with a high body mass index (BMI) have lower levels of intrafollicular human chorionic gonadotrophin, which is associated with reduced embryo quality and pregnancy rates.2

Interestingly, despite the increasing incidence of obesity, the percentage of obese women in need of infertility treatment is less than the percentage of non-obese women requiring similar treatment. Moreover, it is known that endometriosis is a leading cause of infertility among women, and there exists an inverse relationship between body mass index and endometriosis with infertile, obese women less likely to suffer from endometriosis. A new study attempted to reconcile these findings by testing the following hypothesis: Does a higher body mass index in non-obese women with endometriosis improve the chances of conception after in vitro fertilization? The results of the study were published recently in BMC Women’s Health.3

The study recruited 156 women with endometriosis as the sole cause of infertility and segregated them into three groups: underweight (BMI less than 18.5), normal weight (BMI 18.5–24.9), and overweight (BMI 25–29.9). The participants were subjected to treatment protocols for ovarian stimulation, and 35 hours after triggering, eggs were harvested by ultrasound-guided aspiration. After two, three, or five days of egg retrieval, the researchers transferred fertilized embryos back into the uteri of the participants. The researchers monitored the number of retrieved eggs, egg quality, embryos, and the rates of biochemical (a positive test for the pregnancy hormone human chorionic gonadotropin or b-hCG), clinical (confirmed by ultrasound examination), and ongoing pregnancies.

The study found that underweight women comprised 10.3%, normal weight 71.2%, and overweight 18.6% of the study population. It also found that higher grades of endometriosis occurred more frequently in patients with a lower body mass index. The study did not find significant differences in terms of the number of retrieved eggs, quality of eggs, embryos obtained, and biochemical, clinical, and ongoing pregnancy rates between the various weight categories. Therefore, the results of the study do not support the initial premise that higher BMIs lead to improved fertility outcomes in non-obese women with endometriosis. Also notably, an increase in body mass index did not negatively impact fertility outcomes.

In the light of their negative results, the authors propose additional large-scale studies or case-controlled studies to resolve these questions, which could provide information about the optimum body mass index that patients need to achieve before they undergo the in vitro fertilization procedure.

Written by Usha B. Nair, Ph.D.

References:

(1) Maheshwari A, Stofberg L, Bhattacharya S. Effect of overweight and obesity on assisted reproductive technology–a systematic review. Hum Reprod Update. 2007 Sep-Oct;13(5):433-44. Epub 2007 Jun 21. Review. PubMed PMID: 17584821.
(2) Carrell DT, Jones KP, Peterson CM, Aoki V, Emery BR, Campbell BR. Body mass index is inversely related to intrafollicular HCG concentrations, embryo quality and IVF outcome. Reprod Biomed Online. 2001;3(2):109-111. PubMed PMID: 12513872.
(3) Garalejic E, Arsic B, Radakovic J, Bojovic Jovic D, Lekic D, Macanovic B, Soldatovic I, Perovic M. A preliminary evaluation of influence of body mass index on in vitro fertilization outcome in non-obese endometriosis patients. BMC Womens Health. 2017 Nov 16;17(1):112. doi: 10.1186/s12905-017-0457-0. PubMed PMID: 29145852.

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