This pregnancy that I am following has a due date of February 10, 2023 - The embryo is now the size of a pea. On the 2D ultrasound the gestational sac is clearly defined (the black ring), the yolk sac (the white ring) is next to the embryo that can be clearly documented and measured during this stage. We would be able to document the heart rate, however. it may not be a rate at 120 bpm yet. That is normal. Too early for a 3D or HD elective scan.