“…Clinically, the two regimens show therapeutic equivalence and similar effects on weight gain, bone mineral density, bleeding patterns, and frequency of serious adverse effects, which suggests limited differences, if any, in biological responses, despite the 31% dose difference [9]. Furthermore, both DMPA-IM and DMPA-SC result in similar degrees of hypoestrogenism, characterized by systemic estrogen concentrations of 10–100 pg/mL [31, 32, 56]. It is possible that within the initial 30 days following administration of DMPA-IM versus DMPA-SC, with notably different resulting serum concentrations of MPA, some biological responses critical to HIV susceptibility may be differentially impacted.…”