first prenatal appt

so i had to change my dr as i was going to my gyn at first but he does not do deliveries. i’m really sad because he’s an amazing dr that actually listens to me, has never pushed me to get on BC, and took my complaints seriously, which has been really hard for me to find ! when calling the new drs office the woman on the phone was being kind of rude and just had an attitude. after telling her my dob she said “since you’re only 19 you’ll need to get a swab” i was just kind of confused bcs idk what that had to do with anything and she didn’t elaborate any further than that. and why she didn’t mention anything else that’ll happen at the appointment, just that. i’m not really sure what to expect for my first appt so does anybody know what i would need a swab for ? the only thing i could think of is a std test and i don’t even mind getting the test done i’m just kind of confused as to why she implied i would need it based solely off my age ?