Eating disorders are relatively common among women of reproductive age, yet the literature on the effects of maternal eating disorders (ED) on pregnancy outcomes is relatively sparse.  There has been concern that eating disorders may negatively affect gestational weight gain.  Previous studies have demonstrated an association between maternal anorexia nervosa (AN) (both active and past) and lower infant birthweight (as compared to women with no history of ED); however, calculations of the magnitude of this effect have been inconsistent.

Data derived from the Generation R study, a longitudinal population-based birth cohort study conducted in the Netherlands, suggest that maternal eating disorders may have less of an impact on pregnancy outcomes than earlier reported.  In this study, women who enrolled prenatally and gave birth to a live singleton (n = 5256) were included in the analysis.  The authors identified four groups of exposed women: lifetime anorexia nervosa (AN; n = 129), lifetime bulimia nervosa (BH; n = 209), lifetime AN + BN (n = 100), other lifetime psychiatric disorder (n = 1002).  Outcomes were compared with unexposed women (n = 3816).

Overall there was little evidence in this general population sample that lifetime ED was associated with increased risk of poor pregnancy outcomes.

  • Compared to unexposed women, women with AN had, on average, a lower body weight but a higher rate of weight gain subsequently; whereas women with BN had a higher body weight but a lower rate of weight gain.
  • Women with a lifetime history of eating disorder did not differ from unexposed women in terms of risk for prematurity, low birthweight, gestational diabetes, and pre-eclampsia.
  • The only observed differences between exposed and unexposed groups was an increased risk of  fetal distress in women with lifetime AN and a trend toward increased risk of being hospitalized during pregnancy for women with lifetime AN + BN.

While this data is reassuring it is important to consider it along with earlier studies on pregnancy outcomes.  Many of the studies which demonstrated an association between maternal eating disorder and lower birthweight were smaller in size and recruited subjects from clinical populations.  It is likely that these subjects recruited because they have an eating disorder suffer from more severe illness and may also have comorbid psychiatric illness.  They are also more likely to have active illness (as opposed to a history of eating disorder as assessed in the present study).

While the Generation R study suggests that having a history of eating disorder does not exert a strong negative effect on pregnancy outcomes, one of its most significant limitations is that it is not clear how many of the women enrolled in this study had active ED symptoms.  In an exploratory analysis the researchers compared the birthweight of offspring born to underweight women (n = 19) to the birthweight of babies born to normal-weight ED women (n = 269). The mean birthweight of babies born to underweight women with ED was lower  (3275 g; SD 382.8) than that of the babies born to normal-weight women with ED was (3488 g; SD 566.0).  Consistent with earlier studies, this finding argues that women with active symptoms of AN may have worse pregnancy outcomes.

It has been our clinical experience that many women with eating disorders are better able to manage their symptoms during pregnancy than at other times.  In this study, our observation is supported by the finding that women with anorexia nervosa, although they tend to have a lower weight at the beginning of pregnancy, gain weight at a more rapid rate than women without ED.  Similarly, women with a history of bulimia nervosa had a higher body weight but a lower rate of weight gain.

While this population-based study indicates that most women with a history of eating disorder will do well during pregnancy, it will be important in future studies to examine whether all women with ED gain adequate weight in pregnancy, and, if not, what risk factors predict poor gestational weight gain in this population.

Ruta Nonacs, MD PhD

Micali N, De Stavola B, dos-Santos-Silva I, et al.  .  Perinatal outcomes and gestational weight gain in women with eating disorders: a population-based cohort study.  BJOG. 2012 Nov;119(12):1493-502.