Progestin-only pills may be used for menstrual suppression in adolescents. Norethindrone acetate (NA) is the only low-dose (0.35 mg) progestin method available, but optimal dosing for menstrual suppression is unknown. This study seeks to evaluate both prescriber practices in initiating NA 0.35mg and factors that contribute to amenorrhea and satisfaction with the dose.

This is a retrospective cohort study of adolescents ages 9-18 who presented to an academic medical center between 2010-2022. Those with previous hormone therapy were excluded. Data were collected on demographics, menstrual history, bleeding patterns, NA indication, and NA dose. Follow-up care was measured at one, three, and 12 months and included office or virtual visits and portal messages. Heavy menstrual bleeding (HMB) was self-reported. Irregular bleeding (IB) was defined according to ACOG as cycle length varying by >7 days. Prolonged bleeding (PB) was defined as menses lasting >7 days. Data was analyzed using Chi-square or Fisher's exact test. Multivariate logistic regression models assessed outcomes: 1) starting NA 0.35mg; 2) continuing NA 0.35mg; 3) achieving light bleeding or amenorrhea; and 4) reporting satisfaction with bleeding pattern. The University's Institutional Review Board exempted the study.

Of 262 adolescents who initiated NA, 219 completed at least one follow-up. Providers were less likely to start NA 0.35mg for patients with BMI 25kg/m2 (p=0.044), PB (p=0.015), or younger age at menarche (p=0.019). Providers were more likely to prescribe NA 0.35mg if patients were younger (p=0.009) or had estrogen contraindications such as migraines with aura (p=0.008) or risk of venous thromboembolism (p=0.033). Those with PB were 13.1% less likely to continue NA 0.35mg (p=0.043). Additionally, for each year older at menarche, patients were 2.6% less likely to continue NA 0.35mg (p=0.026). Patients with a disability were more likely to continue NA 0.35mg at three and 12 months (p=0.031, p=0.044). Overweight BMI (p=0.01), HMB (p=0.03), and younger age (p=0.034) were associated with lower likelihood of achieving amenorrhea on NA 0.35mg. Patients with IB had significantly more follow-up visits compared to those with weight gain or mood side effects (p< 0.001). Patient satisfaction with NA 0.35mg was negatively associated with IB (p< 0.001).

Providers were more likely to prescribe NA 0.35mg to younger patients, but these patients were less likely to achieve amenorrhea on this dose. Patients who were overweight or had HMB were also less likely to achieve amenorrhea with NA 0.35mg. These results reveal opportunities for improved prescribing practices to help patients achieve menstrual suppression.