July 12, 2021

By Allison Prew

Obesity and Infertility: A Growing Concern

Editor’s Note: This past year, the FACTS team expanded our increasingly popular online elective. Beyond educating medical students about the practical applications of fertility awareness-based methods (FABMs) in family planning, the expanded elective incorporates their medical applications in women’s health. FABMs can be used to diagnose and treat common conditions including endometriosis, polycystic ovarian syndrome (PCOS), infertility, and more.

With the rising prevalence of obesity and infertility, interventions are needed to prevent and treat both conditions, and lifestyle changes are a vital component of such strategies. The article below, written by Allison Prew while on the FACTS elective, summarizes an article[i] titled, “The Overlooked Role of Obesity in Infertility.” It was published in 2008 by Al-Hasani and Zohni in the Journal of Family and Reproductive Health. The authors discuss the role of obesity in infertility and a previously published pilot project, the Fertility Fitness program,v which provides encouraging data on the substantial impact of lifestyle change for women with obesity and infertility.


Obesity is a known risk factor for many conditions. However, one body system is often overlooked: the reproductive system. Infertility is another complication of obesity, made evident by irregular menstrual cycles, reduced pregnancy rates (spontaneous and assisted), and increased miscarriage rates. Central body fat distribution and overall weight excess increase the risk of normogonadotrophic anovulation. Even 5% weight loss may re-establish ovulation or improve a woman’s response to ovulation induction. Obesity may also significantly lower sperm counts in men.


In recent decades, western diets have become higher in complex carbohydrates, fats, and sugars. Passive leisure activities are now more common for both children and adults, and technological advances have made many occupations less physically demanding. This deleterious combination of unhealthy behavioral habits and gradual societal changes contributes to the epidemic of obesity in our society today.

BMI vs. Waist Circumference

Body mass index (BMI) is a common metric to categorize weight, though its use is limited, as it does not reflect body composition. Waist circumference and waist-to-hip ratio (WTHR) measurements are used to further assess obesity. Waist circumference is an approximate index of intra-abdominal fat mass and total body fat. Increased cardiovascular and metabolic disease is noted in men and women with a waist circumference of 102 cm and 88 cm, respectively. WTHR is a simple way to calculate fat distribution by dividing the narrowest waist circumference by the widest hip circumference. In women, this ratio should be ≤0.8, and in men ≤1.0.

When screening for obesity, it is important to consider how fat is distributed throughout the body. Specifically, increased abdominal fat or “apple shape” causes more metabolic problems than increased fat in the hip/thighs or “pear shape.”

Effect of Obesity on Fertility

Although many obese women have healthy pregnancies, obesity can have a multifactorial impact on a woman’s reproductive system. Obesity has been linked to menstrual irregularities, chronic anovulation, PCOS, glucose intolerance, infertility, and pregnancy complications. Increased serum androgen, insulin, and estrogen levels, and lower concentrations of sex hormone-binding globulin (SHBG) are also prevalent.

Obesity may affect ovarian response, requiring a higher dose of clomiphene citrate or follicle-stimulating hormone (FSH) to trigger ovulation, or leading to a poor response to these interventions. Before trying to induce ovulation, PCOS should be ruled out in all obese anovulatory patients. Not all obese women have PCOS, nor are all women with PCOS obese, but a correlation is noted.

Medical benefits of weight loss include improved menstrual cyclicity, restored ovulation, and reduced serum androgen and insulin levels. This leads to enhanced ovarian response to FSH as well as greater success in ovulation induction.


Impact of Obesity on Assisted Reproductive Technology (ART) Success

Any combination of obesity, insulin resistance, and PCOS may compromise the success of ART. Obesity, especially android or “apple shape” obesity, may jeopardize in vitro fertilization (IVF) attempts due to excess adipose tissue and leptin production. This leads to gonadotropin resistance during ovarian stimulation. A higher dose of gonadotropins to overcome the resistance may result in pregnancy complications and greater incidence of miscarriage.

Insulin resistance in PCOS is associated with impaired progesterone synthesis during the luteal phase, indicating a luteal phase defect. Women with

PCOS may not respond well to low-dose FSH stimulation. Luteal phase support is not usually given with ovulation induction protocols. However, women undergoing IVF who do receive luteal support may overcome their hyperinsulinemia and have improved corpus luteum function. Exercise, low-calorie diet, and insulin-lowering drugs may correct these endocrine abnormalities and ultimately improve fertility. How weight loss modifies ovarian morphology is not entirely known, though the alteration in SHBG, free androgens, and insulin sensitivity are thought to play a role.

Falsetti et al (2000) demonstrated enhancement in ovarian morphology with long-term oral contraceptive use,[i] while Crosignani et al (2003) saw similar improvement with a moderate reduction in body weight.[ii] Clark et al (1998) noted that weight loss alone improves menstrual cyclicity, ovulation, and fertility, thereby leading to increased pregnancies.[iii] Per Clark et al, ovulatory cycles and pregnancy was obtained in 40% of previously anovulatory patients after only a 5% reduction in body weight. Following weight loss, the frequency of pregnancy increased by both natural conception and in women using ART. Surgically-induced weight loss has also been shown to restore menstruation and pregnancy, though these options do not come without risk.

Impact of Lifestyle Modification

Clinicians at Queen Elizabeth Hospital in South Australia piloted the Fertility Fitness program.[iv] At the onset of this program, medical infertility treatment was discontinued in women with obesity. The women attended 2-hour weekly meetings for 24 weeks addressing both medical and psychosocial aspects of obesity and infertility. Individualized exercise plans were modified in the first hour, followed by presentations on obesity and reproductive disorders. Appropriate medical treatment resumed after the 6-month program as needed.

Participants lost an average of 10.2 kg, and ovulation was restored in 60/67 previously anovulatory women. The miscarriage rate dropped from 75% (before the study) to 18% (during the study) with 52 pregnancies and 45 live births. The conclusion of this program was that most overweight women with infertility could expect to become pregnant after 6 months of an organized gentle weight loss regimen.

Male Factor

Men who are overweight or underweight have significantly lower sperm concentration and total sperm counts. As a man’s weight increases, blood testosterone levels decrease. The total amount of fat present plays a larger role in sperm production than fat distribution. Increased fat leads to increased estrogen levels, suppression of the hypothalamic-pituitary hormonal axis and alteration of testicular activity. Testosterone production is further decreased by low SHBG levels.

In men, measurement of WTHR is a good starting point to detect and categorize obesity. The presence of abdominal obesity results in changes to glucose homeostasis and metabolism, leading to deteriorating fertility. A high estrogen-testosterone ratio can be treated with aromatase inhibitors, which regulate these hormones and increase sperm production.


Obesity can reduce fertility in women and men. Women require approximately 17-21% of their body weight as fat to menstruate and ovulate normally,i which explains why women who are below their ideal body weight may have anovulatory and irregular cycles. Women above or below their ideal body weight and composition may experience irregular menstruation and anovulation, and therefore reduced fertility. Even modest weight loss may restore menstrual cycles and ovulation, increase sperm production, and improve the chance of conception.


[i] Falsetti L, Gambera A, Tisi G. Efficacy of the combination ethinyl oestradiol and cyproterone acetate on endocrine, clinical and ultrasonographic profile in polycystic ovarian syndrome. Hum Reprod 2001; 16: 36-42.
[ii] Crosignani PG, Colombo M, Vegetti W, Somigliana E, Al-Hasani & Zohni 122 Vol. 2, No. 3, September 2008 Journal of Family and Reproductive Health3 Gessati A, Ragni G. Overweight and obese anovulatory patients with polycystic ovaries: parallel improvements in anthropometric indices, ovarian physiology and fertility rate induced by diet. Hum Reprod 2003; 18: 1928-32.
[iii] Clark AM, Thornley B, Tomlinson L, Galletley C, Norman RJ. Weight loss in obese infertile women results in improvement in reproductive outcome for all forms of fertility treatment. Hum Reprod 1998; 13: 1502-5.
[iv] Galletly C, Clark A, Tomlinson L, Blaney F. Improved pregnancy rates for obese, infertile women following a group treatment program. An open pilot study. Gen Hosp Psychiatry 1996; 18: 192-5.

About the Author

Allison Prew

Allison Prew wrote this summary as a first-year physician assistant (PA) student at Carroll University in Waukesha, WI. Completion of the FACTS FABM course lit a fire under her pre-existing passion for restorative reproductive women’s health care. The course also introduced her to the FACTS Ambassador Program, of which she is now a member. She hopes to continue to share the good news of FABMs with her classmates by inviting a FACTS speaker to her program. After graduation, she hopes to complete the NaProTECHNOLOGY medical training.


The FACTS CME Course is HERE!

The FACTS 4-part CME Course – Fertility Awareness Based Methods (FABMs) for Family Planning and Restorative Reproductive Women’s Healthcare prepares you as a medical professional to present more comprehensive options for family planning and women’s health monitoring and management of a range of reproductive health concerns. Through online lectures, live case study discussions, and readings, this course will explore the broad applications of modern Fertility Awareness-Based Methods (FABMs) and their role in pregnancy prevention, infertility, and women’s health.

The course is divided into four parts; you may elect to do any or all of them and they may be completed in any order. Each part is worth up to 14 AAFP-approved CME credits.

• Part A, An Introduction to Modern FABMs for Family Planning
• Part B, Special Topics in FABMs for Helping Couples Achieve or Avoid Pregnancy
• Part C, FABMs for Restorative Reproductive Medicine and at Various Stages of Life
• Part D, Medical Applications of FABMs

Click here to download the full lesson schedule for the course. 

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