Aw, congrats sa second pregnancy! 300 grams sa 20 weeks ay normal lang, that's actually spot on para sa gestational age mo, my OB said around that range din when I was at 20 weeks with my second. Honestly, the weight measurements can vary a bit depending on the ultrasound equipment and how baby is positioned, so don't worry if the next check shows a slightly different number, that's totally okay. A few of us moms from the group chat compare notes all the time and realized the numbers can fluctuate, pero kung consistent ang growth trend at lahat ay normal sa ultrasound, that's what really matters!