Almost 29 weeks, growth scan?

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My midwife wants me to come back in two weeks for a growth scan. I wasnt offered this in my previous pregnancy. All she did at the appointment was heartbeat check and measuring my belly. I also had 130/80 blood pressure reading. Im just wondering if anyone else was referred for a growth scan and what it entailed and also why their doctor may have recommended it? As excited as I am to see my baby boy again when I didnt think I would get to.. I am now nervous as to why Im getting this done this time but not last time.