Weeks 4 & 5 – Gestational Age / Weeks 2 & 3 – Fetal Age
** Gestational age is the age of the pregnancy from the last normal menstrual period (LMP) and fetal age is the actual age of the growing baby.
Arm and leg buds are visible, but not clearly distinguishable. The heart is now beating at a steady rhythm. The placenta has begun to form and is producing some important hormones including hCG. There is movement of rudimentary blood through the main vessels. The early structures that will become the eyes and ears are forming. The embryo is ¼ inch long by the end of these weeks.
Source: American Pregnancy Association