Resumption of Menses and Normalisation of Body Weight in Adolescents Undergoing Specialised Treatment for Anorexia Nervosa Inpatient or Outpatient Treatment

ABSTRACT Objective To predict resumption of menses (ROM) in patients with anorexia nervosa (AN). Method Females aged 9–17 years with AN, receiving inpatient multimodal treatment (IMT) or family‐based treatment (FBT) underwent assessments at baseline, 6‐month and 12‐month follow‐up (12FU). A menstrual questionnaire recorded date, weight and height at loss of menses (LOM) and ROM occurring up to 30 months after 12FU. A stepwise backward logistic regression analysis evaluated predictors for menstruation at 12FU. Results Among 99 females (age = 14.8 ± 1.7) with AN (restrictive = 85 [86%], binge‐purge = 8 [8%], atypical = 6 [6%]), and percent median body mass index (%median BMI) = 78.9 [IQR = 74.3, 82.8] undergoing IMT ( n = 50) or FBT ( n = 49), 66 (66.7%) had at baseline secondary amenorrhoea, 26 (26.3%) were without menarche, 5 (5.1%) had regular menses, and 2 (2.0%) used contraceptives. At 12FU, menses were present in 45 (45.5%) patients and associated with baseline menarche (OR = 6.04, p = 0.002) and higher 12FU %mBMI (OR = 1.08, p = 0.006) ( R 2 = 0.251). After an average of 15 months of amenorrhoea [IQR = 12.0, 25.0] ( n = 41 with information), %mBMI at ROM (92.0 [IQR = 86.6, 97.8], equalling BMI percentile = 25.0; range = 1–60), was 6.8 %mBMI units > LOM (85.2 [IQR = 79.9, 92.0]; p = 0.001), and 6.5 %mBMI units < premorbid %mBMI (98.5 [IQR = 94.1109.7]; p < 0.001). Conclusions ROM follows weight recovery. Full restoration to premorbid BMI percentile is not necessary for ROM.