In many cases, placenta is low-lying in the early mid-trimester and as the pregnancy advances, it moves up and so, this finding is not of much significance at this stage and only needs a follow up. Uterine artery
notching is observed as a feature up to 22 weeks after which it should disappear. If it persists beyond that, it may be indicative of pregnancy induced hypertension
(PIH), placental abruption
, intrauterine growth retardation
) and increased maternal serum alpha feto protein. The pain in the abdomen and back is directly related to the pregnancy itself and could be due to the stretching of the muscles and ligaments. Please consult your doctor for further advice. Good luck.