What Your Weight Has to Do With Fertility

Obesity can do a number on your ability to get pregnant. But knowing what's behind the connection is the first step to getting around it. We'll show you the way.

by Claire Gillespie Health Writer

Even as a teenager, Jessica knew getting pregnant might be difficult. “I started having irregular periods when I was 16, and at age 22 I was diagnosed with Polycystic Ovary Syndrome (PCOS),” says the 36-year-old mom from New York City, who got pregnant with her daughter after fertility treatment. (She asked us not to use her real name.)

“Aside from my PCOS, I considered myself to be a fit, healthy person despite being overweight,” says Jessica. However, when she first tried to get pregnant, her BMI was 34. “Suddenly, the ‘obese’ tag I’d always shrugged off was at the forefront of my mind,” she says. “We were desperate to start a family, and I didn’t want my weight to be the reason it didn’t happen.”

For the record, BMI alone “is not diagnostic of the body fatness or the health of an individual," according to the Centers for Disease Control and Prevention. Instead, other health assessments including skinfold measurements, diet and physical-activity evaluations, and family history are required to evaluate an individual’s health status and risks.

But for now, the screening tool is still the starting point for any woman with fertility issues because as Jessica experienced, being overweight can impact your ability to conceive. In fact, some fertility clinics won’t treat you at all if your BMI is over a certain level. Our take? Every woman deserves the chance to become a mom if she wants to beregardless of the number on the scale. Here's what you need to know to help make pregnancy happen for you.

The Link Between Obesity and Infertility

Just like the ovaries, fat cells make estrogen; the more fat you have, the more estrogen you produce. And when levels of natural estrogen are high, the body's response can be similar to taking hormonal birth control, meaning infrequent or no ovulation or monthly periods. In fact, an assessment of several studies published in Obesity Review found that ovulation problems are three times more common in obese women.

“Excess weight and abdominal fat increase the risk of having menstrual abnormalities, which occur more frequently with increasing BMI,” says Barry Witt, M.D., a reproductive endocrinologist and medical director with WINFertility and Greenwich Fertility in Greenwich, CT.

To complicate matters, some overweight women like Jessica also have PCOS, another
condition that seriously messes with your hormone levels. As you probably surmised, PCOS causes multiple cysts to develop on the ovaries, which interferes with ovulation and leads to irregular (and sometimes nonexistent) periods. PCOS also can cause acne and excessive body hair, especially on the face. What's more, in many women PCOS also leads to weight gain or makes pounds more difficult to lose, possibly due to its negative impact on insulin, which regulates the body's ability to turn food into energy.

“Obesity is a common finding in PCOS and aggravates many of its reproductive and metabolic features related to insulin resistance," says Dr. Witt. “In the U.S., 60% to 75% of PCOS patients are obese, but in some other countries, only 10% to 40% of PCOS patients are.” (Because of disparities like this, obesity isn't necessarily required for diagnosis.)

Beyond PCOS, obese women are also more likely to have severe forms of endometriosis, according to researchers from the Royal Women’s Hospital and University of Melbourne in Australia. Endometriosis, which occurs when the lining of the uterus grows in other places, such as the fallopian tubes, ovaries or in abominal cavity, can also interfere with fertility.

Why It Can Be Harder to Get Help

As if these issues aren’t enough to deal with, some women who need fertility treatment might face another gut-wrenching obstacle: finding a fertility clinic that accepts obese patients.

A University of Connecticut study of U.S. IVF programs found that about 50% of programs have a maximum BMI at which they will perform in vitro fertilization (IVF) (typically in the range of 40 to 45) while about 25% have a maximum BMI for other fertility treatments (usually ranging from 40 to 50). According to Dr. Witt, typically those programs do not turn patients away, but rather refer them for weight-loss programs including bariatric surgery, when indicated, and have them return for care after reaching weight-loss goals.

A few of the reasons given for these cut-offs include difficulty administering anesthesia and maintaining an airway during the procedure; the presence of comorbidities like diabetes and hypertension; and difficulties visualizing the ovaries on ultrasound along with increased risks with egg retrieval.

According to Dr. Witt, these BMI limits exist because most IVF programs are in out-patient settings where there are strict guidelines in place to reduce the risk of anesthesia-related complications. However, IVF programs within a hospital setting are less likely to have absolute BMI cut-offs as they are better equipped to manage difficult airways during anesthesia, which is the main concern regarding obese patients.

It’s Not All Bad News

Not all women with a BMI over 30 will find it difficult to conceive. Nicola Salmon started her periods at age 13, but only had one or two before being diagnosed with PCOS at age 16, when her BMI was around 30. At that point, her doctor told her she would never be able to have children. But she is now a mother of two, conceived without fertility treatmentand both pregnancies were textbook, with no complications.

“I was at my highest weight when my husband and I decided to start to try to get pregnant. I thought it was going to be impossible so I thought I had lots of time to find another more restrictive diet so I could lose weight and get pregnant,” she says. “But I got pregnant straight away with both of my boys.”

Fertility Treatment Isn’t “One Size Fits All”

Every woman’s pregnancy journey is different, and Dr. Witt stresses that each case must be considered individually. When a patient with a BMI over 30 goes to a fertility specialist for a consultation, they undergo a standard infertility investigation, which includes semen analysis of their partner and ovarian-reserve testing, and if they have irregular periods, they undergo hormonal testing to determine the cause. “The association between obesity and infertility along with the risks associated with pregnancy are reviewed, and lifestyle modifications that combine dietary modification, exercise, and behavioral interventions are discussed,” says Dr. Witt.

However, weight loss is not the end goal. “The benefits of postponing pregnancy to achieve desired preconception weight loss must be balanced against the risk of declining fertility with age,” states Dr. Witt. “Encouraging lifestyle changes to improve health should be the primary focus, but weight loss is not always achievable and failure to lose weight should not be a reason to routinely withhold care.”

In her work as a fat-positive fertility coach, Salmon supports other people in getting pregnant in the bodies they are in. “We take the focus away from weight loss and look at what health-promoting activities they can do to support their physical and mental health and enrich their lives,” she explains.

Salmon also wants to change the narrative around fertility and weight to lessen the emotional stress on people trying to conceive. “Language is really important in this arena,” she says. “The terms ‘obese’ and ‘overweight’ are stigmatizing, because they associate fat bodies with something unhealthy. Being fat does not indicate anything about your health in the same way that being thin does not. People live healthy and unhealthy lifestyles in all BMI brackets.”

Treatment Can Improve Your Chances of Getting Pregnant (Including a Little Weight Loss)

Unlike Salmon, Jessica did need fertility treatments to get pregnant, but this was due to her PCOS and not her weight specifically.

“The need for ovulation medications with PCOS is not dependent on weight,” explains Dr. Witt. “However, the ability to respond to the medications may be affected by weight. Higher doses may be required, and there may be greater resistance to the medications with increasing weight.”

Jessica and her partner tried to conceive naturally for six months, before seeking help. After initial tests confirmed that she wasn’t ovulating, her primary-care doctor prescribed the oral medication Clomid (clomiphene citrate).

“Fertility treatment is often needed to make a woman with PCOS ovulate,” says Dr. Witt. “Typically, this starts with oral medications like clomiphene citrate or letrozole (like Femara). Most PCOS patients will respond and ovulate to these medications, but some will not and will require an injectable follicle-stimulating hormone (FSH) treatment in order to successfully induce ovulation.”

After four cycles of Clomid, an ultrasound showed that Jessica’s midcycle LH (luteinizing hormone, which boosts the reproductive system) surge wasn't strong enough to induce ovulation, and she was prescribed an injection of hCG (human-chorionic gonadotropin, a hormone that supports normal egg development and release) alongside Clomid. It worked, and two years into her fertility journey, Jessica gave birth to her daughter.

Jessica lost 10 pounds while she was on Clomid, but says she didn’t feel pressured to do so by her doctor. “My OB-GYN was really supportive,” she says. “I did my research—I believed that losing weight would improve my chances of conceiving.”

Weight loss isn’t a common side effect of Clomid. ”Some patients gain minimal weight during the treatment as a result of minor fluid retention,” says Dr. Witt. Jessica lost the weight the old-fashioned way: eating a balanced diet within her recommended daily calorie range, and ramping up her exercise level.

“There is evidence that modest weight reduction (5% to 10% of body weight) in obese women with anovulatory infertility improves the pregnancy rate,” says Dr. Witt. “According to a study in the International Journal of Obesity and related Metabolic Disorders, within one year of stopping contraception, 66% of obese women conceive, compared to 81.4% of women of normal weight.”

Fertility Depends on Many Factors

Weight loss aside, patients with a BMI over 30 shouldn’t be treated any differently than patients of a “normal” weight. “All patients presenting for evaluation of infertility undergo an investigation to assess the potential cause,” says Dr. Witt. “If a patient is found to be anovulatory, the cause of the anovulation is sought (e.g., PCOS, hypothyroidism, hyperprolactinemia) and treatment with appropriate medications to induce ovulation is recommended.”

The course of treatment depends on other factors too, such as age and ovarian reserve. If a patient has blocked fallopian tubes (most commonly caused by pelvic inflammatory diseases, sexually transmitted diseases, or endometriosis) or if male infertility is a factor, IVF may be recommended as an initial treatment.

Another concern for obese patients going through IVF is a reduced chance of pregnancy and live birth. A meta-analysis of 33 studies published in The Obstetrician & Gynaecologist showed a 10% reduction in pregnancy and a 16% reduction in live birth. “This has been attributed to poorer egg quality (resulting in lower fertilization) and poorer embryo quality,” explains Dr. Witt.

Dr. Witt also points to possible technical issues during the egg-retrieval procedure if the obese patient’s ovaries are more difficult to access, resulting in lower numbers of eggs retrieved and fewer embryos available for transfer.

How to Increase the Chance of Pregnancy Success

“Ultimately, the goal for fertility clinics is to assist patients in achieving a pregnancy with the greatest chance of resulting in a live birth of a healthy child and to minimize pregnancy complications to the mother and child,” says Dr. Witt.

Whatever your BMI is, there are things you can do to help achieve that goal. “The path toward parenthood in patients struggling with obesity begins with treating the obesity itself,” says David Diaz, M.D., a reproductive endocrinologist and fertility expert at MemorialCare Orange Coast Medical Center in Fountain Valley, CA.

  • First, find a doctor you trust and feel comfortable with, who is willing to take the time to provide you with the support and education about the effects of obesity on your overall health. In Dr. Diaz’s experience, advising patients about managing obesity “frequently improves their chances for conceiving.” This advice may focus on behavior modification to reduce calorie intake, mindfulness in selecting healthy food choices, learning how to read food labels, and stress management to avoid emotional overeating.

  • Look at your lifestyle and make whatever changes you can to improve your health overallbut try to take the focus away from losing all the weight. If your doctor doesn’t refer you to a qualified nutritionist to help you to set and meet realistic goals, ask them to.

  • Take care of your mental health, because going through fertility treatment takes its toll. Professional help is there if you need it! National organizations like RESOLVE and Share Pregnancy & Infant Loss Support can help you deal with infertility and miscarriage/baby loss and point you in the direction of local support groups.

  • Do your research! If you have a higher BMI, contact a clinic first to see if they have BMI cut-offs before attending a consultation. Remember, it’s likely that hospital-based programs will have higher limits.

  • Rely on a support network of caring, non-judgmental family and friends to cheer you on, every step of the way.

  • Remember, your body and your fertility journey are unique. Even if you do have irregular periods, you might just need to get busy under the sheets. You might need fertility treatment, like Jessica, or you might get pregnant without any help, like Salmon. Whatever you do, don’t give up hope.

Obesity and Infertility Meta-Analysis: The Obstetrician & Gynecologist. (2017). “Effect of obesity on assisted reproductive treatment outcomes and its management: a literature review.” obgyn.onlinelibrary.wiley.com

Role of Body Mass On Women’s Reproductive Health: International Journal of Obesity Related Metabolism Disorders. (1997). “Women’s Reproductive Health: The Role of Body Mass Index in Early and Adult Life.” ncbi.nlm.nih.gov

Claire Gillespie
Meet Our Writer
Claire Gillespie

Claire Gillespie writes about mental health, psoriasis, psoriatic arthritis and IBS for HealthCentral. She is a passionate about mental health awareness, and also writes about health and wellness for other sites, including Vice, SELF, Zocdoc, Reader’s Digest, and Healthline. You can follow her on Twitter @southpawclaire.