A non-inferiority analysis of hemoglobin levels in postpartum IUD users in Bangladesh

Objective The objective of this study was to compare postpartum hemoglobin (Hb) between postpartum intrauterine device (PPIUD) and non-PPIUD users. Methods A sample of 3697 postpartum women (475 PPIUD users, 3222 non-PPIUD users) from 5 tertiary referral hospitals in Bangladesh were assessed at multiple time points between 6 weeks and 12 months postpartum. Non-inferiority linear regression analysis compared changes in Hb levels at 29-52 weeks postpartum between the two groups. Non-inferiority was declared if the lower 95% confidence interval of the estimated difference in Hb change since delivery between PPIUD and non-PPIUD users was greater than -0.05 g/dl. Results At approximately 9 months postpartum, 276 women in the PPIUD group (58.1%) and 1086 women in the comparison group (33.7%) attended follow-up. In total, 57.9% of PPIUD users and 61.0% of non-PPIUD users had taken iron supplementation. Change in Hb was 0.02 g/dl (95% CI: -0.16, 0.19) higher in the PPIUD users than the comparison group. The lower limit of the 95% CI was greater than -0.05 g/dl, providing good evidence that PPIUD users were non-inferior to the comparison group in their Hb levels. Conclusion In the presence of offering iron supplementation, and an uptake of just over 60%, no difference in anemia was observed between the PPIUD and control group.