Is It Safe To Use DMPA Injection While Having Minimal PTB?

hello, im 23 years old, last year i was diagnosed to have a minimal ptb, about 3 months after the diagnosis, i got pregnant, i gave birth with a normal delivery and this time, my baby is 5 months old, i am planning to use contraceptive like DMPA injectable, i'm bit worried with my health and for my baby, although i feel so fine, it is alright if i use DMPA..