The truth about body weight and infertility

A recent New York Times article entitled, “When You’re Told You’re Too Fat to Get Pregnant” discussed a woman’s journey to having a child, which involved being counseled against undergoing fertility treatment due to her high body weight. She ultimately underwent bariatric surgery, lost weight and was then able to conceive after an IUI (intrauterine insemination) cycle, a fertility treatment that involves placing the sperm at the top of the uterus, so it is closer to her eggs at the time of ovulation. The article chronicles her fertility journey, which was a long emotional road. The piece also describes how the fertility physicians declined to treat her for infertility until she lost weight. I thank the New York Times for bringing awareness to this important topic but also want to take this opportunity to discuss the complexity of this issue and the increased medical risks that high body weight imposes on fertility treatment and pregnancy.

Body mass index (BMI) is a commonly used measure to assess an individual’s body weight derived by dividing a person’s body mass (in kilograms) by the square of their body height (in meters). A high BMI alone should not be assumed to be the cause of infertility without a thorough history and diagnostic workup. In general, an infertility workup is indicated in the following circumstances:

  • a couple have been trying to conceive for > 1 year, and the woman is < 35 years old
  • a couple have been trying to conceive for > 6 months, and the woman is 35 years old
  • other factors in the couple’s history that may be contributing to infertility (such as irregular cycles, no periods, painful periods, pain with intercourse, history of multiple pelvic surgeries, history of pelvic infections, known or suspected uterine fibroids, polyps or adhesions, known or suspected endometriosis, or known or suspected issues with sperm parameters)

Similar to many other fertility physicians, I am a strong believer in patient education and empowering patients with knowledge. Our goal is to help all of our patients reach their dreams of building a family, but also to make sure we achieve this goal in the most effective and safest way possible. A high BMI impacts the safety of fertility procedures, the success rates with fertility treatments, the health of the mother during pregnancy, and the health of the baby.

Some fertility clinics that are hospital-based have the capability and resources to treat patients with higher body weight without BMI cutoffs. However, some outpatient fertility clinics have BMI cutoffs due to limited procedural and anesthesia resources. These cutoffs are intended for patient safety. It is, however, wrong for these BMI cutoffs to appear arbitrary without an explanation to the patient of these safety concerns. The America Society of Reproductive Medicine (ASRM), one of our governing societies dedicated to the advancement of the science and practice of reproductive medicine, has not implemented specific BMI cutoffs, given the different types of fertility clinics and their varying individual resources and capabilities. ASRM does, however, recommend preconception counseling to address the reproductive and high-risk pregnancy complications associated with high BMIs.

Evidence-based medical practices based on well-designed and well-conducted research studies are important to how we practice medicine. There is evidence that having a high BMI is associated with an impact on fertility, risks with procedures and anesthesia and risks with pregnancy (see below for a list of some of these risks). It is important to explain all risks to patients so that informed decisions can be made.

High BMI and impact on fertility

Many obese women and men are fertile. There is an association with high BMI and,

  • difficulty ovulating
  • miscarriage
  • reduced response to fertility medications
  • decreased egg quality
  • decreased function of the uterine lining
  • lower birth rates
  • impaired reproductive function of the male

High BMI and risks with an egg retrieval (a procedure done with IVF to remove the eggs from the body) and anesthesia

Increased risk of:

  • aspiration (entry of secretions or stomach content into the airway)
  • airway obstruction, laryngospasm, and bronchospasm
  • lower oxygen levels (which can be harmful to patients)
  • requiring intubation (placement of a tube in the mouth and into the airway to help patients breathe)
  • difficult intubation
  • respiratory arrest and even death
  • may need to have the procedure done at a hospital instead of an outpatient clinic due to these risks

High BMI and risks with pregnancy

Increased risk of:

  • preeclampsia
  • gestational diabetes
  • stillbirth
  • preterm delivery
  • C-section
  • wound infections
  • blood clots
  • macrosomia
  • fetal growth restriction
  • fetal anomalies

The fertility physician will discuss these risks and formulate an individual treatment plan for each couple. Weight loss is certainly an important consideration to improve pregnancy outcomes and decrease risk with treatment and pregnancy, but there are other factors to consider when counseling patients with a high BMI.

For example, in a young woman with good ovarian reserve and with ovulation dysfunction as the only infertility factor, it is reasonable to consider modifying lifestyle with diet and exercise to see if weight loss can restore ovulation. For older women with a lower reserve of eggs and less time to achieve pregnancy, it may be more appropriate to work on weight loss concurrently with fertility treatments since postponing pregnancy to lose weight may risk declining ovarian function further. Some patients may decide to pursue IVF and freeze embryos, and then work on achieving their weight loss goals with the transfer of an embryo at a later time. This will allow for more time to achieve weight loss goals. Determining which treatment course can be a difficult decision and is why appropriate education and counseling are crucial.

As your fertility physician, it is our goal to help all patients reach parenthood and to achieve that goal safely. We must carefully educate patients to understand their diagnoses, the risks, the rationale for treatment recommendations, and then arrive at a treatment plan together after appropriate counseling. It is also essential to have an open dialogue on BMI and how healthy lifestyle modifications, medications, or surgery can be important adjuncts to improve outcomes. It is our desire to support and advocate for our patients during this journey and to look out for the safety of mom and baby. If you are not finding these conversations with your physician to be caring and supportive, please consider finding another physician. There are many compassionate fertility physicians throughout the country dedicated to helping you reach your family goals while supporting you every step of the way.

Anu Kathiresan is a reproductive endocrinologist.

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