How do i reduce stretch marks that appear after periods?

Time: If by increase you mean redness - this will improve with time. There are no known effective treatments for stretch marks.

Give it time: Unfortunately, there is no treatment that will get rid of stretch marks, however, stretch marks will fade with time. In the meantime, there are treatments that can help improve thier appearance, these include tretinoin cream, microdermabrasion or laser therapy. These options have varying results. See your dermatologist for these options if the marks do not fade with time.