Early pregnancy refers to the period from conception until approximately 12 weeks gestation. During this time, a woman may not even be aware that she is pregnant as many early symptoms are similar to those of PMS or other conditions. However, during early pregnancy, important developments occur such as the formation of the placenta and the beginning of organogenesis - the process by which organs form from embryonic tissues. It's also a critical time for establishing a healthy foundation for fetal growth and development throughout the rest of the pregnancy.