Eating disorders, encompassing anorexia nervosa and bulimia, affect approximately five per cent of women and have profound medical and psychiatric ramifications.

Eating disorders are associated with significant morbidity and mortality rates and, therefore, early recognition is imperative. Due to the ubiquity of these conditions and the growing number of patients diagnosed at increasingly young ages, it is probable that the majority of O and Gs will encounter such patients in their practice under various guises. Initial presentations may be to an O and G, with the patient not having a prior documented history of eating disorders.

According to the American Psychiatric Association Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DSM V), the proposed diagnostic criteria of anorexia nervosa are associated with a restriction of energy intake relative to requirements leading to a significantly low body weight in the context of age, sex, developmental trajectory and physical health. Anorexia is further associated with an intense fear of gaining weight or becoming fat, or persistent behaviour that interferes with weight gain, despite the fact that the patient has significantly low weight. A common feature of anorexia is a disturbance in the way in which one’s body weight or shape is perceived or persistent lack of recognition of the seriousness of the current low body weight. Finally, in postmenarchal women, amenorrhoea in at least three consecutive menstrual cycles is characteristically described in this condition. Previous criteria defined the weight in anorexic patients to fall below 85 per cent of their expected weight. It is postulated that moving away from this rigid criteria would allow inclusion of adolescents, allowing for normal variability in development, and women with partial syndromes who may still suffer adversely as a result.

Two types of eating disorder are described, a food restricting and a binge eating or purging type. Bulimia nervosa is defined as recurrent episodes of binge eating. An episode of binge eating is characterised by eating an amount of food that is larger than most people would eat during a similar period of time under similar circumstances and associated with a sense of lack of control over eating during the episode. Compensatory measures are then taken in order to prevent weight gain. Typically these include self-induced vomiting; misuse of laxatives, diuretics or other medications; fasting; or excessive exercise. The binge eating and inappropriate compensatory behaviours both occur, on average, at least once per week for three months.

Female reproduction resulting in pregnancy requires an investment of a large amount of energy. Energy stores are diverted to the baby while in utero and, subsequently, energy is required during parturition, lactation and child rearing. This comprises the largest expenditure of energy in a woman’s lifetime.¹ As such, survival mechanisms exist in undernourished women to protect them against the additional energy demands of an ensuing pregnancy. This is achieved by interplay between the reproductive axis and the nutritional status, leading initially to a reduction and ultimately cessation of ovulation when energy stores are deemed insufficient to support a pregnancy. Energy balance appears to be a more important factor than absolute weight or body mass index (BMI); clinicians should bear in mind that anovulation may precede significant weight loss.² Conversely, moderate improvements in nutritional status may restore fertility in most cases.

Malnourishment has profound medical ramifications. The Dutch famine, which affected the western parts of the country between October 1944 and May 1945, resulted in a fall of an average daily calorific intake from 1500 kilocalories per capita to less than 700 kilocalories per capita. Subsequently, the birth rate nine months after the onset of the famine decreased. It has been postulated that a maturation process of the hypothalamic-pituitary-gonadal axis in children can be undermined by periods of starvation and may have reproductive sequelae in adulthood. From the Dutch experience it was retrospectively seen that the reproductive lives of girls experiencing the famine when aged between three and 13 years old had a 1.88 fold increase (95 per cent CI = 1.29-1.74) of having no or fewer children than desired.³

Eating disorders predominantly first develop in adolescence, with 90 per cent presenting before 25 years of age. Clinical sequelae of anorexia and bulimia depend on timing of the disease in relation to puberty. Presentations may include pubertal delay, primary or secondary amenorrhoea, pubertal arrest, cold intolerance, constipation or diarrhoea, fatigue, frequent fractures, nerve compression, easy bruising and scalp hair loss and/or dental problems associated with enamel erosion.^4,5 The earlier these conditions are recognised, and treatment initiated, the higher the chance of successful remission. In the case of anorexia, full recovery is anticipated in a third of patients; while with bulimia, resolution is seen in 74 per cent. However, achieving these recovery rates requires a protracted period of follow up and surveillance and, despite this, relapse occurs in a third of patients.⁶

Fertility

Anorexia nervosa and bulimia nervosa affect up to five per cent of women of reproductive age causing amenorrhoea, infertility and, in those who do conceive, an increased likelihood of miscarriage.⁷ Menstrual periods often cease after a 10–15 per cent decrease in normal body weight. Amenorrhoea may occur in normal BMI bulimic women, indeed amenorrhoea may persist in 30 per cent of patients who have recovered from anorexia and regained a normal weight.⁸

Infertility is a common presentation in patients with eating disorders; indeed, primary infertility may be the initial presenting manifestation of eating disorders. Identification of this is imperative both for the successful treatment and in order to deal with potential deleterious ramifications during pregnancy and later on in the woman’s life. In the fertility clinic setting, a disproportionately high number of patients have eating disorders. Of patients presenting with amenorrhoea or oligomenorrhoea, it has been estimated that over 50 per cent may have an underlying eating disorder. It is worth keeping in mind that patients may not recognise that their behaviour constitutes an eating disorder or be in denial of this. Sensitively broaching eating habits, exercise, nutritional intake and examination in combination of body weight and height should be routinely completed with all patients presenting to an infertility clinic. Infertility may be due to a combination of anovulation, sub-physiological levels of sex hormones that may result in reduced libido and, in some, a rejection of sexual activity. Restoration of the hypothalamic-pituitary-ovarian axis depends on weight gain and resolution of underlying psychological issues. Persistence of amenorrhea despite appropriate weight gain is in some cases related to the duration of anorexia; the longer the duration of the illness the longer it may take for resumption of menses. Underlying anxiety disorder or abnormal eating habits may also contribute to a persistence of amenorrhoea.^9,10,11,12 Interestingly, several studies have demonstrated that live birth rates in patients with low BMI are not reduced in comparison with normal BMIs. In a Norwegian study of patients receiving ART, those with BMIs <18.5kg/m2 had identical live birth rates to those patients with BMIs ranging from 18.5 to 25kg/m2.¹³ This may reflect the fact that BMI is not a sensitive measure of energy stores as described above.

Pregnancy

Early symptoms of pregnancy may mimic symptoms associated with eating disorders. These include delay in menstrual cycle, hyperemesis and fatigue. As such, pregnancy may on occasion present late. Hyperemesis gravidarum may be caused by a variety of factors. It is however worth noting that intractable, severe hyperemesis may be associated with increased frequency in those with eating disorders.^14,15 Indeed, some women with eating disorders have increased incidence of impaired weight gain during pregnancy and of delivering infants with lower birth weights, microcephaly and intrauterine growth-restricted babies.^16,17 Women’s response to pregnancy varies, some studies report an improvement in symptoms as a direct consequence of their pregnancy, with the motivation of maintaining their health and health of their babies.^18,19 This is especially seen in women who have previously been treated and have a supportive network. Others find it difficult to distinguish their pregnancy with weight gain. With a profound fear of uncontrolled weight gain, pregnancy is perceived as adopting poor body image and as such concomitant anxiety and depression are commonly. The postpartum period is a stressful time associated with profound physiological and hormonal changes. These are coupled with great emotional upheavals coping with a newborn that can precipitate dysfunctional eating habits. A large proportion of women who report an improvement in eating disorder symptoms during pregnancy, regress in the postpartum period. As such, pregnant women with a current or past history of eating disorders should be monitored closely postpartum so that potential issues with either mother or baby may be addressed.

Understanding the nature of these conditions and the various presentations in an O and G context is imperative. Adopting a non-judgemental, holistic, multidisciplinary view is undoubtedly advantageous in management of these patients