Capturing patients preconceptionally, we have an opportunity to counsel and promote healthy lifestyle interventions for optimal reproductive and long-term health outcomes. We take this seriously, as we should. When patients come to us for help conceiving, we look at their body mass index (BMI) and we often take a pause when it is high. Do we recommend weight loss? If so, how much?

A BMI of 30 kg/m2 is the convention for examining adiposity and health risk. While it may be a reasonable cutoff for balancing sensitivity and specificity to identify those at risk for chronic disease related to excess body fat, it is not clear whether it is the best cutoff for identifying women at risk for adverse reproductive outcomes or the provision of fertility treatment.

Searching for facts in this month’s issue of Fertility and Sterility, Kim et al. (1

Kim J, Patounakis G, Juneau C, Morin S, Neal S, Bergh P, et al. The Appraisal of Body Content (ABC) Trial: increased male or female adiposity does not significantly impact in vitro fertilization laboratory or clinical outcomes. Fertil Steril. In press.

) investigated the use of bioelectric impedance analysis in determining associations between adiposity and reproductive outcomes after in vitro fertilization, arguing that bioelectric impedance analysis is a better measure of adiposity than BMI. The investigators enrolled 1,889 couples and found a slightly higher blastocyst formation rate and a higher prevalence of very low birthweight infants among women with ≥40% body fat when compared with other women. Otherwise, all of the other outcomes were equivalent. Traditional BMI categories did not do a better job in assessing risk.

The investigators conclude that their analysis does not contradict that obesity may impact natural fertility, but rather it suggests that in vitro fertilization/intracytoplasmic sperm injection may mitigate the negative impact of obesity on fertility and that given the increased obstetrics risks, patients should be encouraged to pursue a healthy lifestyle and achieve a normal body weight. However, given their findings, one must ask, what is a normal body weight when it comes to assessing reproductive risk?

When it comes to weight loss for restoring ovulation for women with polycystic ovarian syndrome and obesity, many of us have been taught to recommend a 5%–10% loss in body weight. Women with BMI's greater than 40 kg/m2, often require a higher percentage of weight loss to see improvements. For women who require assisted reproductive technology (ART) to conceive, many of us have advocated for BMI cutoffs in the provision of ART services (2Kelley A.S. Badon S.E. Lanham M.S.M. Fisseha S. Moravek M.B. Body mass index restrictions in fertility treatment: a national survey of OB/GYN subspecialists.). But even the largest studies of obesity and ART outcomes only demonstrate a marginal impact of maternal BMI on ART success (3Luke B. Brown M.B. Missmer S.A. Bukulmez O. Leach R. Stern J.E. et al.The effect of increasing obesity on the response to and outcome of assisted reproductive technology: a national study.). What is not clear from these studies is whether they are limited because women with obesity are denied access to fertility care. The rationale is that maternal obesity increases the risk of adverse obstetric outcomes.While the obstetric risks associated with increased maternal BMI are real, it is not clear if it is any higher than the risk of adverse outcomes among another group of women we often rally behind with a patient-centered approach—women of advanced reproductive age. When working with women of advanced reproductive age, risk assessment focuses on cardiovascular and metabolic fitness. A medical framework could also apply to our approach to fertility treatment in patients with obesity, as much of the risk associated with obesity during pregnancy can be attributed to cardiovascular and metabolic comorbidities (4Establishing an ethically and medically sound framework for integrating BMI limits into infertility care for obese women.).The American College of Obstetrics and Gynecology recently published a committee opinion on ethical considerations for the care of patients with obesity (5ACOG Committee Opinion No. 763: ethical considerations for the care of patients with obesity.). The document outlines that it is unethical for physicians to refuse care that is within the scope of safe practice solely based on an arbitrary BMI cutoff or because a patient has obesity. Instead, physicians should focus on patient-centered counseling. When physicians lack specialized training, experience, or institutional resources (which includes appropriate anesthesia or procedure room capabilities) they should refer patients to physicians with expertise in obesity.

If we agree that fertility treatment is not elective, it is time for us to shift to a patient-centered approach for fertility care in women with obesity.

References

Kim J, Patounakis G, Juneau C, Morin S, Neal S, Bergh P, et al. The Appraisal of Body Content (ABC) Trial: increased male or female adiposity does not significantly impact in vitro fertilization laboratory or clinical outcomes. Fertil Steril. In press.

Kelley A.S. Badon S.E. Lanham M.S.M. Fisseha S. Moravek M.B.

Body mass index restrictions in fertility treatment: a national survey of OB/GYN subspecialists.

J Assist Reprod Genet. 36: 1117-1125Luke B. Brown M.B. Missmer S.A. Bukulmez O. Leach R. Stern J.E. et al.

The effect of increasing obesity on the response to and outcome of assisted reproductive technology: a national study.

Fertil Steril. 96: 820-825

Establishing an ethically and medically sound framework for integrating BMI limits into infertility care for obese women.

in: Jungheim E. Obesity and Fertility. Springer, New York: 179-191

ACOG Committee Opinion No. 763: ethical considerations for the care of patients with obesity.

Obstet Gynecol. 133: e90-e96Article InfoPublication History

Published online: July 05, 2021

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DOI: https://doi.org/10.1016/j.fertnstert.2021.05.114

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©2021 Published by Elsevier Inc. on behalf of the American Society for Reproductive Medicine

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