The hormonal intrauterine device (hIUD) induces local changes to reproductive biology (e.g., uterus, endometrium) and has some systemic physiological effects (e.g., hormones, mood, etc.). However, the systemic hormonal changes observed in women with eumenorrheic (EUM) cycles have not been thoroughly investigated in hIUD users. Therefore, this study aimed to establish the concentrations of serum estrogen (i.e., estradiol) and progesterone for hIUD users and compare those concentrations to EUM women. Sixteen hIUD users and 15 EUM women enrolled in a larger investigation had venous blood collected during two testing sessions separated by ~14 days for hIUD and in the early follicular (EFP) and mid-luteal (MLP) phases for EUM women. The luteinizing hormone surge was determined using urinary ovulation kits, and menstrual cycles were tracked using calendar-based counting to confirm the EUM cycles. Progesterone and estradiol enzyme-linked immunoassays were used to analyze the serum samples. The endogenous estrogen and progesterone concentrations were similar across testing sessions in hIUD users (p = 0.720), whereas for EUM women, estrogen and progesterone were greater in the MLP than the EFP (p = 0.004). Based on these differences between estrogen and progesterone in hIUD users and EUM women, hIUD users should be treated as a unique group of females.
Wiggins et al. (2026) studied this question.