Reproductive Issues in Anorexia Nervosa

Elizabeth R Hoffman; Stephanie C Zerwas; Cynthia M Bulik


Expert Rev of Obstet Gynecol. 2011;6(4):403-414. 

In This Article

Perinatal Issues in Anorexia Nervosa


Despite having less gestational weight gain and babies with lower birthweights than the general population,[27,31,38] women with anorexia nervosa do not appear to have increased complications with most aspects of delivery. There are no differences in preterm births, gestational hypertension/preeclampsia, induced labor, vacuum extraction, use of forceps, or breech presentation in women with past or recent anorexia nervosa compared with the general population.[19,27,31,38,39] However, women with anorexia nervosa may have a higher risk of cesarian section. Higher rates of cesarian delivery in women with recent anorexia nervosa were seen in a small USA cohort (compared with nonsymptomatic women with eating disorders) and in a larger controlled study in New Zealand (compared with non-eating disorder controls),[6,39] but risk of cesarian delivery was not increased for women with current anorexia nervosa before pregnancy in the Norwegian MoBa population-based cohort or in a large controlled study in Sweden.[19,27] It is possible that this discrepancy could reflect cross-national trends in cesarean rates, or that eating disorder symptoms were more severe in women before pregnancy in both the USA and New Zealand cohorts compared with the Norwegian and Swedish cohorts, which included women with a wider range of disease severity. Women with more severe, active symptoms of anorexia nervosa during pregnancy may be viewed as high risk by their obstetricians, resulting in more frequent cesarian sections.[10]

Birth Outcomes

Women with both recent and past anorexia nervosa have babies with lower birthweights in comparison to women with no history of eating disorders.[6,7,27,31,38,40] One study found that this lower birthweight was largely explained by the lower prepregnancy BMI of mothers with anorexia nervosa.[31] Several controlled studies have also shown that women with any history of an eating disorder (not specifically anorexia nervosa) are at increased risk for having small-for-gestational-age babies;[27,40] however, this increased risk was not found in a study specifically evaluating women with histories of anorexia nervosa.[19]

While birthweight may be significantly lower, no differences have been found in Apgar scores at 5 min for babies of women with anorexia nervosa compared with babies of women with no history of an eating disorder.[19,27] Earlier retrospective studies found that recent symptoms of restriction in anorexia nervosa were associated with lower Apgar scores at 5 min than babies of women who did not have active symptomatology at conception.[41,42] However, a recent prospective study reported no differences in Apgar scores for babies of women with current versus past symptoms of eating disorders.[39] Thus, it appears that the presence of eating disorder symptoms during pregnancy is not necessarily associated with lower Apgar scores 5 min after birth.

The presence of eating disorders during pregnancy may influence sex ratio at birth. In the Norwegian MoBa cohort study, women with active anorexia nervosa or bulimia nervosa before pregnancy were less likely to give birth to males than a non-eating disorder referent group.[43] It is known that lower caloric intake is associated with fewer male births,[44] and that the nutritional content of foods ingested during pregnancy can influence sex ratio at birth. Interestingly, in animal studies, male fetuses appear to be more sensitive to fatty acid deficiencies than females.[45] Therefore, it is possible that the typical low-calorie, low-fat diets of many women with anorexia nervosa may be selectively harmful to male fetuses during gestation.

It is likely that sufficient gestational weight gain plays a crucial role in determining birth outcomes for women with anorexia nervosa. Earlier case studies describing women with severe restricting-type anorexia nervosa throughout pregnancy reported significantly worse outcomes on all measures (intrauterine growth restriction, preterm delivery, small for gestational age, high occurrence of breech presentation, increased vaginal bleeding and low Apgar scores) than more recent prospective controlled and population-based studies.[7,41,42,46,47] While these recent studies include larger sample sizes and greater statistical power to detect differences on many of these outcomes, the severity of illness in the women with eating disorders during pregnancy is probably much more varied than in the earlier case studies.

Indeed, in the population-based Norwegian cohort study, mothers with anorexia nervosa reported greater weight gain than mothers without eating disorders, suggesting that, in light of their lower prepregnancy BMI, they were gaining appropriate amounts of weight during their pregnancy. Potentially owing to this adequate weight gain, studies of this cohort found few differences in birth outcomes for women with anorexia nervosa than the referent group. One early study of anorexia nervosa during pregnancy even reported that for those women with anorexia nervosa who achieved adequate weight gain during their pregnancy, the occurrence of delivery complications and rate of birth defects was no different than that of the general population.[47] Thus, in clinical practice, monitoring of gestational weight gain in women with suspected past or present anorexia nervosa throughout pregnancy appears to be critical and may mitigate against adverse outcomes.


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