my OB advised to follow 1st TVS dahil maaaring mag-iba ang EDD during 2nd or 3rd trimester ultrasound dahil nakadepend ang AOG or EDD sa size ni baby. if normal ang cycle, you can follow based from LMP. also, hindi naman nagkakalayo ang mga EDDs of different ultrasounds. maaaring manganak earlier dahil EDD ay 40weeks.