History of maternal anorexia linked to small infant size

1. Women with a history of anorexia nervosa were more likely to have small-for-gestational-age (SGA) infants compared to healthy women.

2. Women with active eating disorders in pregnancy experienced the worst perinatal outcomes, including higher odds of SGA infant and preterm birth.

Evidence Rating Level: 2 (Good)

Study Rundown: Eating disorders are common among reproductive-age women and affect roughly 5-8 percent of pregnant women. The majority of eating disorders can be divided into 2 categories: anorexia nervosa, characterized by extreme calorie restriction and deprivation, and bulimia nervosa, described as compulsive binging and purging. In addition to increasing morbidity risk for women, eating disorders have been suggested to be associated with worse outcomes for the developing neonate. Prior studies demonstrate an associated with lower birthweight and intrauterine fetal growth restriction (IUGR) among pregnant women with anorexia, though other studies have failed to reproduce this finding. IUGR, however, is associated with known adverse outcomes including cardiovascular and metabolic diseases such that any relationship between maternal eating disorder and IUGR is important. Research by this study group has previously demonstrated that a history of maternal anorexia nervosa was associated with lower birth weight infants and that this associated was mediated by low maternal pre-pregnancy BMI and smoking during pregnancy. In this study, they re-evaluated the relationship between maternal eating disorder behavior and birth weight in a larger, population-based cohort.

Results demonstrated that women with a history of anorexia were more likely to have small-for-gestational-age infants, and outcomes were worst among pregnant women with an active eating disorder. Strengths of this study included a large, population-based sample, the use of objective outcome measurements of growth, and stratification by eating disorder status (e.g. active vs. former). The presence of an eating disorder, however, was self-reported, which introduces the opportunity for recall bias. Future studies might collect information on weight gain in pregnancy and incorporate eating disorder journal entries or interviews with nurses to assess how maternal behavior, including weight gain, exercise and eating habits, in pregnancy are associated with neonatal weight gain and in utero development.

Click to read the study in BJOG

Relevant Reading: Risk of major adverse perinatal outcomes in women with eating disorders

In-Depth [prospective cohort study]: Using data from the Danish National Birth Cohort, a longitudinal population-based cohort, researchers compared women with anorexia nervosa (n = 1609), bulimia nervosa (n = 1693), and both anorexia and bulimia (n = 634) to unexposed women (n = 76 724) using both linear and logistic regression models. The primary outcomes included size at birth (birth weight, length, head and abdominal circumference), gestational age at delivery, SGA and large-for-gestational age (LGA).

Both history of anorexia and active anorexia in pregnancy were associated with delivering an SGA infant (aOR:1.4, 95% CI:1.2-1.7; aOR:2.9, 95% CI:2.0-4.2, respectively, p < 0.1). Women with active anorexia during pregnancy experienced greater odds of preterm birth compared to healthy women (aOR = 1.8, p = 0.049). Maternal cigarette smoking during pregnancy mediated the effect of maternal anorexia on offspring SGA slightly but did not meaningfully impact effect estimates. Bulimia alone was not predictive of adverse neonatal outcomes, but women with a history of both anorexia and bulimia were at greater odds of having an SGA fetus.

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