Introduction
To evaluate the effectiveness of the levonorgestrel intrauterine system (LNG‐IUS) in obese women with heavy menstrual bleeding in Counties Manukau Auckland area, New Zealand.

Methods
Prospective observational study in a tertiary teaching hospital. Twenty women with heavy menstrual bleeding (HMB) who agreed to treatment with the LNG‐IUS and had a body mass index (BMI) of >30 kg/m2 were recruited between May and December 2014. The women completed two validated tools (Menstrual Impact Questionnaire and the Pictorial Bleeding Assessment Chart) at recruitment, 6 and 12 months follow‐up. Demographic, medical and laboratory variables were obtained from the relevant CMH databases. Data on side effects and satisfaction were obtained from the women at 12 months.

Results
The median age (range) and BMI of the 20 women were 40.5 years (27–52 years) and 40.6 kg/m2 (30–68), respectively. Three LNG‐IUS were removed due to infection and pain and these women were subsequently booked for a hysterectomy. The reduction in menstrual loss was estimated at 19.7% per month (95% CI (12.5%, 26.2%); P < 0.001), which translates to 73.2% per period of 6 months (95% CI (55.3%, 83.9%)) and 92.8% per period of 12 months (95% CI (80.0%, 97.4%)). The six items in the quality of life measure improved significantly in 14 women but only 12 women were satisfied with the treatment. Conclusion The LNG‐IUS was an effective treatment for 67% of obese women with heavy menstrual bleeding over a 12‐month period, as assessed by the reduction in menstrual bleeding and the improvement in the quality of life measures.