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. In the presence of offering iron supplementation and an uptake of 60%, PPIUD use does not cause anemia or impede postpartum Hb recovery in the first 12 months postpartum.