Eating Disorders and Pregnancy: Understanding Their Complex Relationship

By Reva Schlanger MS, RD, CDN

Pregnancy is a time filled with angst and excitement. While there is a lot of information out there on ways to conceive and guidelines around pregnancy, there is not as much information on the relationship between eating disorders and pregnancy. A common misconception is that those actively in an eating disorder will not be able to conceive. This, however is untrue as there are many studies noting the relationship between eating disorders while in pregnancy. Current evidence suggests that eating disorders play a significant part on pregnancy, pregnancy outcome, and infant outcomes.¹⁴ Many have a chronic course, and result in psychiatric and medical comorbidities for both mothers and their offspring. The literature on the relationship between maternal eating disorders and pregnancy indicates a decrease in eating disorder symptoms during pregnancy, followed by a revival when in postpartum. Here we will review the current scientific evidence on the effects of pregnancy on eating disorder symptoms, the effects of eating disorders on pregnancy, and the effects eating disorders have on pregnancy outcomes.

Do Eating Disorders Affect Fertility?

Eating disorders affect 5-7% of women of child-bearing age, leading to many women managing pregnancy with an eating disorder.¹ The onset of these disorders is typically in adolescence or young adulthood, a critical phase of a woman’s reproductive life. Eating disorders have important impacts on the endocrine system including a decrease in hormone production, especially in women with anorexia nervosa. While this accounts for reduced fertility in women with severe and active anorexia nervosa, recent advances in fertility treatment make it possible for women with eating disorders to still conceive. Two small studies have found a high rate of eating disorders in women attending fertility clinics, (approximately 10%).^2,3 Women with anorexia nervosa seem to have lower rates of pregnancy in the long term, though there are inconsistent findings in the existing literature.^4,5 It is important to note that many women with a past or current eating disorder do become mothers of healthy children.

Research has shown that fertility problems appear to be less frequent in women with bulimia nervosa, compared with women with anorexia nervosa. Important to note that there is more information on the relationship between fertility and anorexia than with bulimia. However, it is suggested that women with bulimia nervosa are more often at a normal weight and have regular menstrual cycles leading to more consistent ovulation.⁶ To have a better understanding of fertility and bulimia nervosa, there needs to be more research/literature on the topic.

Effects of Pregnancy on Eating Disorder Symptoms

Few studies have investigated the patterns of eating disorder symptoms during pregnancy. The current literature on healthy pregnant women indicates a more positive attitude to weight and body image during pregnancy.^9,10 However this might not apply to women who have concerns about shape and weight pre-pregnancy, including women with eating disorders. On a positive note, research focusing on the course of eating disorder symptoms in women with active bulimic disorders during pregnancy shows an improvement in bulimic symptoms.  Few women, however, reported a complete cessation of symptoms and behaviors during pregnancy. Results from a large Norwegian cohort showed similar patterns of remission for a sample of women with bulimia nervosa while pregnant.¹² Fewer studies have investigated symptom changes in anorexia nervosa; however, one of the above studies showed a smaller decline in symptoms compared to bulimia nervosa. Despite the reported decrease in eating disorder related behaviors during pregnancy, weight concerns and body dissatisfaction remained prevalent. Therefore, it is important to seek help from a team of eating disorder professionals as well as maternal-fetal medicine specialists.

Effects of Eating Disorders on Pregnancy Outcomes

Despite the variable quality, size and nature of samples, most studies on the effects of active or lifetime eating disorders suggest an increased risk of adverse obstetric and pregnancy outcomes. Higher levels of prematurity have been reported in three studies of women with lifetime or current anorexia nervosa, with an approximate two-fold increase in risk.^4,5 Most studies have highlighted lower birthweights in samples of infants born to women with active or lifetime eating disorders, particularly in the case of children born to mothers with active or life-time anorexia nervosa. One study published has researched the obstetric outcomes of women with binge eating disorder (BED), and results suggest an increased risk of large-for-gestational-age offspring in this group of women.¹⁴ There is also convincing evidence for an approximate two-to-three-fold increase in risk of miscarriage secondary to maternal active bulimia nervosa.^7,12 In two small studies on the outcome of pregnancy in a sample of bulimic women, a higher than expected number of fetal complications (breech presentation, caesarian delivery) were found in women with active bulimia nervosa.^8,11

Several studies, suggest that the postpartum period is a high-risk period for the recurrence or exacerbation of eating disorder symptoms. Most of the studies that have investigated the postpartum period to date have shown that most women whose symptoms decreased during pregnancy, relapsed, or returned to pre-pregnancy behaviors after giving birth.^11,14 In particular, a study of 94 women with active bulimia nervosa, found that in more than half of the sample, bulimic behaviors were more severe in the postpartum period than pre-pregnancy. Some studies have investigated other psychological symptoms in this population, mainly focusing on depression. Women with current and/or past eating disorders have high rates of postnatal depression; over 30% across studies.^7,14

Patients who report having an eating disorder should be offered an in-depth assessment of the type and severity of symptoms present. Research has shown that most women with eating disorders will be motivated to change their disordered behavior or will have lower levels of symptoms during pregnancy. However, a small portion of patients may still have eating disorder behaviors or be ambivalent about the need to change these behaviors in pregnancy. This is likely driven by the importance placed upon controlling weight, shape, and appearance, which is a common theme amongst certain eating disorders. Most women with current or past eating disorders will also be unsure about adequate nutritional requirements and will be intensely preoccupied with just how much weight they should put on during pregnancy. They might need very precise information from a dietitian about the need for incorporating food from each nutritional group in their diets and about daily energy requirements. Energy requirements typically increase the farther a woman is in her pregnancy.¹³ Seeking help from an eating disorder dietitian is preferable as they can help support pregnant women in obtaining proper nutrition while working on some of the maladaptive eating behaviors caused by the eating disorder.

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