- Germinal stage: This stage begins at conception and lasts for about two weeks. During this time, the fertilized egg divides into many cells and implants into the lining of the uterus.
- Embryonic stage: This stage lasts from about two weeks to eight weeks of pregnancy. During this time, the major organs and body systems begin to develop.
- Fetal stage: This stage lasts from eight weeks of pregnancy until birth. During this time, the fetus grows and matures. The organs and body systems continue to develop, and the fetus prepares for birth.