shot to protect my blood from mixing with my baby's blood ?

so yesterday i went to the doctor for the first time ( i'm 7 weeks , 1 day ) & everything went really good . the baby's heartbeat is steady & everything seems to be developing right , & he/she is healthy & on track 😍 a few hours after i left i got a call from the doctor saying my bloodwork came back & that i needed to come back in right away for a shot . i had the doctor explain it to me better & basically it's because my blood type is O- & the baby's take after their father's blood type which he thinks his is B+ , & if anything goes wrong & my blood winds up mixing with the baby's blood it's gonna cause complications & i'll lose it . only because i have this weird blood type 😩 so i went back & got it of course but has anyone else had to go through this before ?  & apparently i have to get the shot every time i become pregnant .. which probably explains my miscarriage that happened a little over a year ago .