During the second month the embryo increases in length and in weight. It now measures roughly one and a half inches. The most obvious change is the development of the face, with a prominent forehead, blank-appearing eyes which have just acquired eyelids, a mouth, and a broad nose. Small external ears have formed at the sides of the head at two months as well. Another obvious change during this month is the development of arms, legs, which started in the 5th week as mere paddles on the sides of the body but which, by the end of the second month, have fingers, toes, wrists, elbows, ankles and knees. Internally, the greatest change during the second month is the complete reorganization of the heart, which by the end of this month has four chambers just like the adult heart.

The internal sex organs have developed sufficiently to reveal a microscopic difference between the ovaries of a female child and the testicle of a male child.

The external sex organs will develop during the 3rd month. Miniature bones are formed during this month. They are mostly composed of cartilage, which though soft and flexible provides a degree of support. Also, miniature muscles become attached to the small bones.