Ay sis, marami naming kilala na may placenta previa sa first at second trimester, at honestly most of the time umakyat pa talaga ang placenta as the pregnancy progressed! A few of us mums dito sa group had the same worry, and by third trimester ultrasound nila, okay na everything. At 23 weeks ka pa lang kaya definitely may time pa for things to shift, ang uterus mo lumalaki pa, so it's possible talaga na mag-move ang placenta. But definitely worth checking with your OB on your next visit para ma-monitor mo regularly at mapigilan if may bleeding, kasi yan ang main concern with previa naman. Wishing you all the best, mama!