By Barkley Smith
Editor’s Note: Physical activity is a lifestyle intervention with tremendous impact on mind, body, and spirit. Studies continue to show its far-reaching benefits on multiple areas for people of all ages. The study featured this week was published by Maher et al in 2024 [1] and was summarized by Barkley Smith while on the FACTS elective. The authors found that regardless of duration or intensity, most interventions to increase physical activity will improve fertility outcomes. Published in Reproduction, their findings emphasize the need for clear exercise prescriptions for women with obesity and infertility as well as more detailed descriptions in future research of the exercise recommendations implemented in each study.
Introduction
The article, “The Current Landscape of Exercise and Female Fertility Research: A Narrative Review,” discusses physical activity as a treatment option for female infertility. [1] The medical definition of female infertility is the inability to achieve pregnancy after 12 months of unprotected sexual intercourse if under 35 years old, or 6 months of unprotected sexual intercourse if over 35 years old. Some definitions of female infertility also include over 6 months of fertility-focused intercourse regardless of age.
The causes of female fertility are multifactorial, but physical activity is a potentially modifiable risk factor. Women with obesity are three times more likely to experience infertility than women with a body mass index (BMI) within the normal range. The higher rates of infertility among women with obesity may be due to hormonal and metabolic dysregulation and related disorders. In the 2024 article [1] summarized below, Maher et al discuss a prescription for varying exercises as an intervention for women with obesity and infertility and report on fertility outcomes as well.
“Women with obesity are three times more likely to experience infertility than women with a body mass index (BMI) within the normal range, (and) the higher rates … may be due to hormonal and metabolic dysregulation and related disorders.”
Methodology
To accomplish their objective, the researchers did a literature search in the English language within CINAHL, Cochrane, Embase, and PubMed for the time frame of January 2005 until January 2021. They searched keywords such as fertility, obesity, and physical activity. Inclusion criteria included women ages 18 to 40 with a BMI over 28 and infertility for over 1 year. Out of 500 articles found, 117 went through a full text review; of those, 16 were chosen to compare for the narrative review. While reviewing the articles, the researchers examined fertility outcomes, which they classified as the rate of conception, pregnancy, and live birth rates, hormonal improvement, and regularity of menstrual or ovulation cycle.
Regarding the exercise data, the researchers classified each exercise as cyclic or acyclic and physical activity as continuous and noncontinuous. They further differentiated the physical activity prescribed by examining exercise techniques, load, intensity, duration, and recovery time.
Results
Overall, 15 of the 16 studies showed a positive correlation between physical activity and fertility outcomes. Most studies examined moderate-intensity cyclic exercise regimens. No differences were found when comparing group versus individual exercises.
In a study by Gorczyca et al, women with obesity and infertility who participated in a weight loss program had a 50% pregnancy rate. [2] Al-Eisa et al found that menstrual cycles were more regular following an exercise intervention. [3] The same study on the impact of exercise reported improvements in fasting blood glucose and insulin levels in 67% of participants. [3]
“In a study by Gorczyca et al, women with obesity and infertility who participated in a weight loss program had a 50% pregnancy rate.”
In another study, Mutsaerts et al compared two groups of women with a primary endpoint of a healthy singleton at 24 months. [4] One group began physical activity 6 months prior to attempting to conceive with or without artificial assisted reproduction; the other group began infertility treatment immediately. [4] The results were confounded, and no significant differences were found after the 24-month analysis was removed. [4]
Discussion
The findings of the review by Maher et al [1] suggest exercise interventions have a positive effect on fertility, especially in women with infertility and obesity. This lifestyle modification aligns with the approach taken by many women who seek out fertility awareness-based methods (FABMs), as these methods of achieving or avoiding pregnancy are non-invasive, inexpensive, and place an emphasis on lifestyle and understanding one’s own body.
“The findings of the review by Maher et al suggest exercise interventions have a positive effect on fertility, especially in women with infertility and obesity.”
As only 16 out of 117 peer-reviewed studies were chosen, there is a question about the inclusion and exclusion criteria, and why certain articles were excluded. Additionally, the study design did not follow similar protocols between group, individual, or supervised physical activity. Future research could also improve the selection process by choosing those articles in which more details are known about the physical activity implemented, such as the type of physical activity, time per week, and intensity level for all articles discussed. Finally, to avoid delaying conception in couples with infertility for the sake of research, a similar trial could enroll women with obesity and irregular periods who wish to avoid pregnancy, implementing a physical activity requirement and observing hormonal and menstrual regularity with or without an FABM as a measure of fertility outcome.
In conclusion, the evidence supports physical activity as a positive intervention to improve fertility outcomes. Women and couples interested in using FABMs to avoid or achieve pregnancy are a subset of patients likely to benefit from this knowledge, as lifestyle modification is already an integral part of family planning for these patients. Still, more research is needed with an emphasis on methodology to ensure future studies can be reproduced and compared to maximize their clinical applications.
References
[1] Maher RA, Wadden K, Fuller D, Basset F, Murphy H, McGowan E. The current landscape of exercise and female fertility research: a narrative review. Reproduction. 2024 May 31;168(1):e220317. doi: 10.1530/REP-22-0317. PMID: 38642581.
[2] Gorczyca, Anna M.; Washburn, Richard FACSM; Steger, Felicia L.; Marsh, Courtney; Donnelly, Joseph E. FACSM. Weight Loss, Physical Activity, And Conception In Obese Infertile Women: 1935 Board #196 May 31 2. Medicine & Science in Sports & Exercise 50(5S):p 466, May 2018. | DOI: 10.1249/01.mss.0000536614.49670.28
[3] Al-Eisa E, Gabr SA, Alghadir AH. Effects of supervised aerobic training on the levels of anti-Mullerian hormone and adiposity measures in women with normo-ovulatory and polycystic ovary syndrome. J Pak Med Assoc. 2017 Apr;67(4):499-507. PMID: 28420905.
[4] Mutsaerts MA, van Oers AM, Groen H, Burggraaff JM, Kuchenbecker WK, Perquin DA, Koks CA, van Golde R, Kaaijk EM, Schierbeek JM, Oosterhuis GJ, Broekmans FJ, Bemelmans WJ, Lambalk CB, Verberg MF, van der Veen F, Klijn NF, Mercelina PE, van Kasteren YM, Nap AW, Brinkhuis EA, Vogel NE, Mulder RJ, Gondrie ET, de Bruin JP, Sikkema JM, de Greef MH, ter Bogt NC, Land JA, Mol BW, Hoek A. Randomized Trial of a Lifestyle Program in Obese Infertile Women. N Engl J Med. 2016 May 19;374(20):1942-53. doi: 10.1056/NEJMoa1505297. Erratum in: N Engl J Med. 2018 Jun 28;378(26):2546. Erratum in: N Engl J Med. 2018 Jun 28;378(26):2546. doi: 10.1056/NEJMx180013. PMID: 27192672.
ABOUT THE AUTHOR
Barkley Smith is a fourth-year medical student at the Philadelphia College of Osteopathic Medicine in Georgia. She completed her undergraduate education at Texas A&M in College Station, TX. She plans to do her residency in emergency medicine and has a strong interest in women’s health, recognizing that many individuals seek care in the emergency department for fertility-related concerns.
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