From the time the fertilized egg is laid to the birth of the fetus, the 280 days in between, the fetus is changing all the time as it grows and develops inside the mother-to-be. It takes about three months from the formation of the fertilized egg to the development of its first human form. This stage is fragile and prone to problems, and it is also the most critical period for the growth and development of the fetus. During the first month of pregnancy, the fertilized egg lays in the uterus and divides, forming part of the brain and part of the nerve tissue. In the second month of pregnancy the heart develops and can beat, the facial organs can be distinguished, the ears continue to take shape, the skin is thin, blood vessels are visible, and the fetus can move. In the ninth month of pregnancy, the organs develop and the embryo is formed before it can be called a “fetus” in the true sense of the word. In the third trimester, the fetus takes on its first human form, measuring about 65 mm in length, with its head occupying about half of its body, its fingers and toes fully separated, its bones beginning to harden, and its joints taking shape. It takes about three months for a fertilized egg to develop into a humanoid fetus, which is an important period for the growth and development of the fetus’ body organs.