Eating disorders in pregnancy

How do eating disorders affect fertility?

Most women with bulimia nervosa (even those with a normal body mass index) have menstrual irregularities, and 5% of these women report secondary amenorrhoea. Women with eating disorders may therefore present to their general practitioner with infertility. However, an 11.5 year follow-up study of 173 women with bulimia nervosa found that 75% became pregnant, which indicates that fertility problems are not more common in these women.3 Women with active anorexia nervosa have more difficulty conceiving. Menstruation and return of normal fertility can be delayed in up to 30% of women with anorexia nervosa who regain normal weight.4

Women with irregular or absent periods often assume that they cannot conceive. This can lead to inadequate use of contraception and the risk of unplanned pregnancies.5

Does pregnancy affect eating disorders?

Pregnancy can be a stressful and anxious time for some women, especially those with an eating disorder. The accompanying weight gain and change in body shape can lead to recurrence or worsening of the eating disorder. Conversely, the eating disorder may improve because of the woman’s worries about its adverse effects on her unborn baby.6

Evidence suggests a variable course for women with past or current eating disorders who become pregnant. The eating disorder may continue unchanged during the pregnancy.2 Two prospective studies found that symptoms may improve in women with bulimia nervosa, whereas those with anorexia nervosa were more likely to relapse postpartum.6 7 Another prospective case-control study reported that pregnancy might lead to a relapse in women with a history of an eating disorder, most probably in the first six months postpartum.8

A recent community based prospective cohort study of 12 254 women with a history of an eating disorder, an active eating disorder, obesity, or no eating disorder reported that women with an eating disorder generally improved throughout pregnancy. However, these women reported continuing concern and anxiety about their weight, dieted more often, used more laxatives, exercised more, and practised more self induced vomiting than the other groups of pregnant women.9

Do eating disorders affect pregnancy and fetal outcomes?

The evidence here is limited and sometimes conflicting. Many studies are retrospective or questionnaire based, which can lead to recruitment bias and recall bias. Other studies are based in hospital clinics, which are not representative of community populations.

Overall it seems that a current eating disorder, particularly active anorexia nervosa, carries an excess small risk to the mother and the fetus. A recent large cohort study of women with anorexia nervosa, women with bulimia nervosa, women with both disorders, and controls found that women with bulimia nervosa were significantly more likely to have a history of miscarriage and those with anorexia nervosa were significantly more likely to have smaller babies compared with the general population.10

Another retrospective study compared women with a history of anorexia nervosa, bulimia nervosa, atypical eating disorder, and controls. It found that women with a history of an eating disorder had a higher rate of miscarriage, small for gestational age babies, low birth weight babies, babies with microcephaly, intrauterine growth restriction, and premature labour (especially if the mother’s body mass index was <20).8

However, a recent large cohort study in Sweden suggests that a past history of anorexia nervosa in itself may not be associated with negative birth outcomes.11

Maternal problems reported include psychological upset, postnatal depression, anaemia, increased risk of hyperemesis gravidarum, and more problems with episiotomy repair.8

Do eating disorders affect the postpartum period and breast feeding?

Women with eating disorders are at increased risk of postnatal depression. A retrospective case-control study of 94 women with eating disorders found that a third of them developed postnatal depression compared with 3-12% in the general population.5 A large retrospective questionnaire study of women with one or more pregnancies found that those with eating disorders were more likely to report depression during pregnancy and postpartum.12

Women with an eating disorder are more likely to have an underlying affective disorder (up to 40%), and this together with the added stresses of pregnancy (body image change, weight gain, loss of control) is thought to make these women more vulnerable to postnatal depression.

Several studies have found that women with eating disorders are at increased risk of relapse of the disorder postnatally, especially those with a history of anorexia nervosa or a high frequency of binge eating at conception.7 13

Women with eating disorders seem to stop breast feeding earlier than the general population. A retrospective questionnaire study surveying 454 women at three to seven months postpartum found that 11.5% self reported an eating disorder and these women were significantly less likely to be breast feeding at three months postpartum.2

Do eating disorders affect the mother-infant relationship?

Research on mothers with eating disorders suggests that they may be particularly controlling of their infants, both during play and at meal times. A controlled cross sectional study of 1 year old children of mothers with eating disorders, found that the mothers were more critical of their children and more conflict occurred during meal times than in controls. The children tended to weigh less than controls, and the children’s weight correlated inversely with the mother’s concern about her own body shape.14

How are women with eating disorders managed before pregnancy?

Eating disorders often go undetected by general practitioners; research suggests that only 10% of women with bulimia nervosa are identified and only half of these are referred for treatment.15 Prepregnancy counselling sessions and the first antenatal visit are good opportunities to screen for eating disorders, as women are perhaps more open to advice and help at these times. National Institute for Health and Clinical Excellence guidelines1 recommend opportunistic screening in vulnerable groups (box 1).

Women with active eating disorders should be advised to postpone pregnancy if possible, until they have largely recovered. Treatment should be offered, with early referral to a specialist eating disorders service, especially for anorexia nervosa.

Women with eating disorders who are considering pregnancy should be asked about drugs, particularly laxatives, appetite suppressants, or diuretics, which may not be safe in pregnancy.

Early education about body changes, cravings, and hyperemesis gravidarum can help the woman prepare for pregnancy.

How are women with eating disorders managed in pregnancy?

Women with an active eating disorder should be referred early to an obstetrician with an interest in high risk pregnancies and ideally to a specialist eating disorders service.

The availability of specialist eating disorders services varies considerably across the United Kingdom, and it may be more appropriate to refer in the first instance to the local psychiatric service.

How are women with eating disorders managed postpartum?

Areas of concern postpartum include the woman’s psychological wellbeing, breast feeding, and relapse of the eating disorder. Offering advice and encouraging partners to be supportive can be helpful.

These women should be offered extra support with breast feeding as many have difficulties and are more likely to give up earlier.

Relapse may be identified by monitoring weight and asking about eating behaviour and self induced vomiting. It is worthwhile to ask about drugs such as laxatives, diuretics, and appetite suppressants. Some women may use these drugs in an effort to lose weight quickly without realising the potential hazard they pose to a breastfed baby. If rapid weight loss occurs, leading to concern about recurrence of anorexia nervosa, referral is indicated.

Bulimia nervosa and binge eating can sometimes be managed in the community with self help guides. High dose fluoxetine (60 mg daily) has a specific anti-bulimic effect and may help patients regain control over their eating if combined with self help therapy.16 Referral is indicated if simple interventions do not help or if the eating disorder is severe or complicated by other psychological problems.

Eating disorders are a relatively uncommon but important problem in women of reproductive age, as they can be affected by pregnancy and can adversely affect mother and baby. Box 3 provides a summary of the management of pregnant women with eating disorders. The key elements are recognising the disorder at an early stage; developing a good relationship with the woman and her partner; clearly communicating with the general practitioner, midwife, and obstetrician; and having a low threshold for asking the advice of a specialist in eating disorders. These women often need ongoing support so continuity of care is vital.