Welcome to HCM
Your past obstetrical history is good.
This type of placenta is known as placenta preavia or low lying placenta as detected by USG. 13 weeks is early stage of pregnancy
. As pregnancy advances there is migration of placenta away from internal cervical os.
So you should be in regular check up by USG for placenta localization.
Do not worry much ,take some precaution and vigilant for painless bleeding or spotting per vagina.
Avoid Coitus and exceesive weight lifting.
Take adequate rest .
Regular blood pressure monitoring.
Best of luck .
Any further question you are welcome to ask.