Expectant mums with anorexia nervosa at increased risk of adverse pregnancy outcomes

The presence of anorexia nervosa during pregnancy may contribute to elevated risks of clinically important adverse pregnancy outcomes, with a significant proportion of the excess risk due to an underweight prepregnancy body mass index (BMI) or gestational weight gain below the recommendation, as shown in a study.

The study included 241 pregnant people with a diagnosis of anorexia nervosa and 6,418,236 without an eating disorder diagnosis.

Adverse pregnancy outcomes included gestational diabetes, gestational hypertension, pre-eclampsia, anaemia, antepartum haemorrhage, premature rupture of the membranes, premature labour, caesarean delivery, oligohydramnios, placenta previa, chorioamnionitis, placental abruption, severe maternal morbidity, small for gestational age, large for gestational age, low birthweight, and preterm birth (by timing and indication).

Poisson regression models were used in the analysis with adjustments for demographic factors, anxiety, depression, substance use, and smoking. A mediation analysis was also conducted.

Pregnant people with vs without an anorexia nervosa diagnosis were more likely to have anaemia, preterm labour, oligohydramnios, severe maternal morbidity, a small for gestational age or low birthweight infant, and a preterm birth between 32 and 36 weeks with spontaneous preterm labour (adjusted relative risks range, 1.43–2.55).

Underweight prepregnancy BMI mediated 7.78 percent of the excess in preterm birth risk and 18.00 percent of the excess in the risk of having small for gestational age infants. Meanwhile, gestational weight gain below the recommendation mediated 38.89 percent of the excess in preterm birth risk and 40.44 percent of the excess in the risk of having low birthweight infants.

The findings underscore the importance of treating anorexia nervosa and comorbid conditions and letting pregnant people with anorexia nervosa know that preconception weight and gestational weight gain may improve pregnancy live birth outcomes.