Hi The postpartum rash occurs due to many different reasons, but one of the most common ones is due to an allergic reaction. Post-partum when the uterus starts returning to the closest to normal size, a few contents from conception or from the placenta that were left behind in the uterus get absorbed. This is perfectly normal and happens in mang women. But at times, your husband s DNA from thise contents absorbed into your body results in an allergic reaction. I would recommend a visit to your doctor for a blood evaluation that can confirm/rule out an allergic reaction. Once this is done, we can take things forward from there. Best wishes.