MRCP2-1001

A 35-year-old woman in her third trimester of her first pregnancy presents with a rash that initially appeared on her abdomen and has now spread to her upper thighs and buttocks. Upon examination, you observe an erythematous rash with small papules that have merged into patches in some areas. The rash is most prominent around her stretch marks on her abdomen, with the area around her umbilicus appearing unaffected. There are no blisters present. What is the probable diagnosis?