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How eating disorders impact fertility

How eating disorders impact fertility

12 min read

Eating disorders are complex conditions with significant implications for both our physical and mental health. Over the last 50 years, the prevalence of eating disorders hasn’t changed significantly — the lifetime prevalence of eating disorders in the U.S. is 2.7%, according to the National Institute of Mental Health. Eating disorders are more than twice as prevalent among females (3.8%) than males (1.5%).

People of all ages, genders, socioeconomic status, and ethnicities can suffer from eating disorders. The age at which people (especially those with ovaries) start experiencing disordered eating, however, keeps getting lower. And beyond the physical and emotional repercussions of eating disorders, they’re also shown to have an impact on reproductive health and fertility.

In this post, we’re diving into the research to find out how eating disorders, both past and present, affect people’s ability to conceive and their pregnancy outcomes; what people with a history of eating disorders should be aware of if they’re trying to conceive; and what biological mechanisms link eating disorders and fertility.

Main takeaways

  • All forms of current eating disorders are associated with a higher risk of irregular or absent ovulation, which may decrease chances of conception.
  • Pregnancy rates at six months and overall number of pregnancies are not affected by past eating disorders.
  • People with ovaries who have a current eating disorder may be at higher risk for adverse pregnancy outcomes like miscarriage and low birth weight.
  • Pregnancy can result in conflicting feelings for people with past or present eating disorders. Talking to a doctor or mental health specialist can help.

A quick overview of eating disorders

The broad category “feeding and eating disorders” that you’ll find in today’s Diagnostic and Statistical Manual V (aka the bible for mental health professionals) comprises four different types of eating disorders, each with its own symptoms and underlying biology. Here’s what clinicians generally keep an eye out for for each:

  • Anorexia nervosa: Restricted eating, fear of gaining weight, distorted body image.
  • Bulimia nervosa: Repeated instances of binge eating, feeling lack of control while eating, compensatory behavior to avoid weight gain.
  • Binge eating disorder: Similar to bulimia nervosa, but without the compensatory behavior to avoid weight gain. This is the most common eating disorder among Americans
  • Avoidant restrictive food intake disorder: a relatively new diagnosis previously referred to as “selective eating disorder.” It’s similar to anorexia in that both disorders involve limitations in the amount and/or types of food consumed, but unlike anorexia, this does not involve distress about body shape or size.
  • Eating disorder not otherwise specified: Irregular eating or weight-related behavior that doesn’t neatly fit into the specified categories above.

Despite each eating disorder being associated with different behaviors, there are some common threads among the three that have important implications for general health and fertility. People with eating disorders are typically nutritionally compromised, and are more likely to experience amenorrhea (aka no menstrual cycles) or oligomenorrhea (irregular menstrual cycles), which may cause issues when trying to conceive.

Though nutrition is compromised in people with all three types of eating disorders, which can itself have significant impacts on general health, there are some biological differences between the groups that have important implications for reproduction and fertility.

One more important thing to note before we dive in: Not all people who have a specific eating disorder look the same or act the same. It’s totally possible for two people to meet the diagnostic criteria for anorexia, one with a body mass index (BMI) of 29 (which is classified as “overweight”), and one with a BMI of 15 (which is classified as “underweight”). That people with eating disorders come in all different shapes and sizes makes it even easier for eating disorders to fly under the radar.

(It’s important here to note that while BMI is an imprecise and historically problematic measurement tool, it’s the most common metric healthcare providers use to predict body-fat percentage. As a result, many studies use BMI as a proxy for body-fat percentage.)

Often, the people who present in a treatment clinic or hospital for an eating disorder represent the most extreme cases, and aren’t necessarily representative of all people who meet the diagnostic criteria for an eating disorder. That’s why in doing the research for this article, we tried to (when possible) focus on population-based studies that collect data from a representative sample of all people, rather than on clinic-based studies that collect data from what likely represents a subset of the most severe eating disorder cases.

Trying to conceive with a current eating disorder

There are many necessary steps for conception and pregnancy to occur, and one big one is ovulation. Ovulation is when a developed egg is released from the ovary, and has the potential of being fertilized by sperm. If ovulation doesn’t occur, pregnancy doesn’t occur — full stop. That’s why keeping tabs on ovulation is so important for people trying to conceive. (For tools to help you do that, check out our Ovulation Test and free ovulation tracking app.)

Anorexia and irregular ovulation

For people with current eating disorders, ovulation and menstruation may become irregular or stop completely. Though irregular periods or lack of periods aren’t part of the diagnostic criteria for anorexia nervosa, between 70-90% of people with symptoms of anorexia report that they’ve previously stopped getting their periods for at least three months; an additional 5-10% report irregular periods.

The underlying biology behind irregular ovulation and anorexia is fairly well understood. Anorexia (and the state of being underweight, more broadly) is associated with a decrease in a hormone called leptin. Though it’s typically thought of as the hormone controlling appetite and weight, it has another important superpower: It regulates the activity of the hypothalamus in the brain, which ultimately controls the production of hormones like luteinizing hormone (LH) and follicle-stimulating hormone (FSH) that are crucial for ovulation. Low levels of leptin can “shut down” the hypothalamus and reduce levels of these important reproductive hormones, resulting in irregular or absent ovulation.

Other eating disorder subtypes and irregular ovulation

Periods and ovulation may look comparatively more typical in people with other eating disorder subtypes, though still different than what we see among people who don’t have eating disorders. About 40% of people with bulimia and 50% of people with other types of disordered eating have regular periods, while about 30-40% of people with these subtypes don’t get their periods at all.

Across subtypes, there are certain things that make someone more or less likely to experience irregular periods and ovulation. An atypically low BMI, atypically high BMI, high levels of exercise, and low levels of caloric intake all increase the risk of amenorrhea or oligomenorrhea.

Does having an eating disorder make you infertile?

Changes in menstrual cycle regularity are by no means permanent in eating disorders. Some studies suggest that the majority of people with anorexia and amenorrhea can expect that their cycles will become typical within the first six months of them getting closer to their “normal” weight for their height. (Each person has a genetically predetermined ideal weight for them, which may or may not follow traditional BMI curves.)

That being said, irregular periods don’t mean you can’t get pregnant. In fact, people with eating disorders are twice as likely to have an unwanted or unplanned pregnancy — a finding that has been replicated in two population-based studies (meaning we can be pretty confident it’s something worth paying attention to). The authors of these studies hypothesize this is because people may assume irregular or absent periods means the chance of getting pregnant is zero, and as a result, they stop using contraception.

People with unplanned pregnancies (who previously assumed they simply wouldn’t be able to get pregnant) may be less likely to seek early prenatal and pregnancy care, limit alcohol intake, and start taking a prenatal supplement — all of which may have significant implications for the health of the developing fetus down the line. None of these things are unique to people who have eating disorders, but may be important to emphasize because of the higher risk of unplanned pregnancy within the group.

Trying to conceive after recovering from a past eating disorder

While it’s clear that a current eating disorder could affect your chances of conception, what about having a past eating disorder — are there any long-lasting effects of eating disorders that could linger and affect fertility?

The data generally indicates that having a past eating disorder doesn’t affect your current ability to conceive. One large population-based study in the UK found that chances of conception in the first six months of trying to conceive were similar across people with a history of anorexia, a history of bulimia, and no history of eating disorders (~74%). Though people with ovaries who have a history of eating disorders were more likely to have seen a doctor for fertility-related issues (which could indicate effects of past eating disorders on fertility), they weren’t more likely to have received fertility treatment after seeing a doctor (which wouldn’t necessarily indicate effects of past eating disorders on fertility). Other studies have too found that people with past eating disorders aren’t more likely to undergo fertility treatment.

People with ovaries who have a history of anorexia also don’t differ in the number of pregnancies and age of their first pregnancy relative to those with no history of eating disorders. But the lack of differences between people with and without a past of eating disorders doesn’t mean that the experience of pregnancy, or pregnancy outcomes, are the same across these two groups.

Does having an eating disorder impact your pregnancy?

Here, we’ll talk about some of the pregnancy outcomes that have been studied in relation to eating disorders that have received the most research attention.

Miscarriage: There’s some data that suggests people with ovaries who have either current or past anorexia report more miscarriages as compared to those with no history of eating disorders. The fact that people with a past history of anorexia are at increased risk for miscarriage may be because people with a history of anorexia have lower BMIs on average (even when they’re in remission), and low BMI is associated with higher miscarriage risk in general. That being said, findings here are inconsistent — not all studies report associations between present or past anorexia, as well as present or past bulimia, and miscarriage.

Some data points to a link between binge eating disorder and miscarriage. It’s possible that the link between miscarriage and binge eating disorder is also tied to BMI: People with binge eating disorder on average have higher BMIs than the general population, and high BMI is associated with higher miscarriage risk.

Low birth weight: Low birth weight is associated with infant mortality, and potentially for certain health outcomes in adulthood (e.g., cardiovascular disease). Population-based studies find that active anorexia, but not active bulimia, past anorexia, or past bulimia, are associated with lower birth weight. Others suggest that a history of anorexia may have a slight impact on birth weight, but not enough to be clinically meaningful. While clinic-based studies have more consistently shown links between eating disorders and low birth weight, that’s likely because people presenting in clinics have more severe forms of eating disorders, meaning studies based on them likely overestimate the effect of eating disorders on low birth weight.

Perinatal mortality: In pregnant people with active anorexia, some studies suggest no differences in perinatal mortality (stillbirths or infant mortality within the first week), and others suggest significant increases. Some also suggest that people with past anorexia, but not people with past bulimia or binge eating disorder, are also at higher risk for infant mortality.

While we can’t say for sure that any differences we see in pregnancy outcomes are caused by eating disorders, we can loosely speculate about what they are likely not caused by (though, of course, this unscientific process of elimination isn’t a stand-in for rigorous prospective studies to try and answer this question). Prenatal supplements are designed to deliver the necessary nutrients for the birthing parent during pregnancy and for the developing fetus, and studies suggest prenatal supplement use is similar in people with and without eating disorders. Self-reported micro- and macro-nutrient consumption is also similar during pregnancy in people with and without a history of eating disorders, though there are some serious concerns about the validity of self-reported dietary data.

Bottom line: The evidence is mixed on whether past and current eating disorders affect pregnancy outcomes, though studies more consistently point to no effect of past eating disorders on pregnancy outcomes — meaning any potential effects of eating disorders are likely reversible.

If you’re struggling with an eating disorder and are currently trying to conceive or may start trying to conceive in the near future, it’s worth starting a conversation with your doctor about treatment first. Dr. Katherine Hill, MD, the medical director of Equip Health, a clinical care team that provides at-home eating disorder treatment, has this advice: “If somebody is struggling with eating and wants to get pregnant, they should first try to get their eating under better control with the help of a healthcare provider like an OB, as well as an eating disorder-experienced therapist and dietitian — some people really find benefit from that.” The organization Project Heal can help with access to mental healthcare providers who specialize in eating disorder treatment.

On the research front, we’re hopeful to see more large-scale studies on links between present and past eating disorders on pregnancy outcomes, and studies that investigate what exactly causes potential differences in pregnancy outcomes among those with current eating disorders, past eating disorders, and no eating disorder history.

The experience of pregnancy with an eating disorder

Pregnancy is associated with a broad spectrum of physical and emotional changes, and some of these changes may be difficult to deal with for people with current or past eating disorders.

Physical changes during pregnancy

The CDC recommends that pregnant people with a “normal” BMI (i.e., between 18.5 and 24.9) gain somewhere between 25 and 35 pounds over the course of their pregnancy. For people whose BMIs classify them as “underweight” (i.e., they have a BMI below 18.5), the recommendation is to gain between 28 and 40 pounds. For people who are used to limiting their caloric intake or the foods they eat, exercising a lot, or otherwise engaging in any other behaviors to limit their weight, this sudden pregnancy-induced weight gain can be extremely psychologically challenging, and there’s data to suggest people with anorexia who are underweight don’t always up their caloric intake enough during pregnancy. And on the other hand, people with bulimia and binge eating disorder are more likely to report excess weight gain during pregnancy.

Because adequate weight gain and nutrition are important across all of pregnancy for the health of both the birthing parent and the fetus, it’s important to address any feelings and behaviors that might negatively impact healthy weight gain and nutrition when trying to conceive or very early on in pregnancy.

Dr. Hill explains that awareness of these significant changes is key, as well as discussing your concerns with your medical team — even if it’s uncomfortable. “While challenging, it is important to disclose difficulties with eating up front so that you can be more closely monitored and supported through what is already a stressful time for somebody's body and mental health,” Dr. Hill explains. “Perhaps if your OB knows you’re suffering from eating issues, then they may be more sensitive when measuring or discussing weight at each visit.”

Not all people with past or present eating disorders express psychological difficulties with the bodily changes associated with pregnancy, though — for some, it’s quite the opposite. Some pregnant people report feeling liberated from focusing on achieving a certain number on the scale or body shape, and instead focus on the unbelievably cool and coordinated suite of physiological changes that support the growth and development of a fetus.

And whether it be because of societal pressure or because of personal changes, existing eating disorders in pregnant people often go into remission during pregnancy. Almost 80% of people with unspecified eating disorders before pregnancy go into remission during pregnancy, as do 34% of people with bulimia. Dr. Hill’s theory is that “it's finally socially acceptable to gain weight.”

Emotional changes during pregnancy

In general, people with eating disorders report higher levels of anxiety and depression before, during, and after pregnancy as compared to people with no history of eating disorders. The American College of Obstetrics and Gynecology (ACOG) recommends that doctors perform comprehensive mental health screening for those trying to conceive, those who are currently pregnant, and those who have recently given birth.

If you fall into any of these categories and have any symptoms consistent with eating disorders, these symptoms may be worth bringing up with your doctor either during a mental health screen, or whenever you have the chance to chat with them. Though your doctor will be able to point you to resources and next steps that are best for you, we’ve also rounded some up at the end of this article.

The bottom line

Trying to conceive and pregnancy are mentally challenging no matter what, but they can be exacerbated by current or past eating disorders. While eating disorders can impact reproductive health, chances of conception, and pregnancy outcomes, seeking treatment before trying to get pregnant can reduce some of those risks. Since some of the research on pregnancy outcomes specifically is mixed and at times inconclusive, if you’re trying to conceive or pregnant and think you may have disordered eating, talk to your doctor as soon as you can — there are services and resources that can help.

We’ve rounded up a few to get you started:

This article was medically reviewed by Dr. Jane van Dis, MD, FACOG. Dr. van Dis is a practicing OB-GYN, volunteer clinical faculty at USC Keck School of Medicine where she serves on the Gender Equity in Medicine and Science Committee, CEO of Equity Quotient, co-founder of OB Best Practice, and co-founder of TIME'S UP Healthcare.

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Talia Shirazi, PhD

Talia is a clinical product scientist at Modern Fertility. She's passionate about reproductive health + behavioral neuroendocrinology. Talia received her PhD in biological anthropology at Penn State.

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