 Nowadays, multiple treatment modalities have been applied clinically to treat striae gravidarum, such as laser therapy, microdermabrasion, platelet-rich plasma injectionPRP, etc. To some extent, these treatments can improve striae gravidarum. In this clinical trial, the investigators are going to treat striae gravidarum by using two different kinds of combination therapies. One is fractional laser and PRP injection synergy, and the other one is treated by nanofat grafting with PRP injection. 