Injectable contraceptives

Im an FTM po, kakadeliver ko lang last week and first time ko lang rin mag-injectible contraceptives, yung every 3mos. ask ko lang, if ever mag-do kami ni mister, safe ba iputok sa loob? since naka injectable naman na ko. PS. wala pa po ko balak makipag-do agad-agad 😆 asking lang how injectable works. thank you