Eh, panjang 17.98cm tu macam slightly on the smaller side untuk 30 weeks, tapi honestly jangan stress sangat lagi, growth spurts boleh jadi inconsistent at this stage, and scanning accuracy pun ada margin of error yang okay je. A few of my mum friends had similar readings tengah-tengah pregnancy but their babies caught up beautifully later on, so it's really not a red flag on its own. But definitely mention this to your doctor at the next checkup so dia can monitor and maybe do a repeat scan if needed, just to make sure everything's progressing well for baby. Take care, mama!