But first, how is a pregnancy dated? Pregnancy terminology can be confusing. There are two ways of dating pregnancy: Gestational Age and Fertilization Age. Most health care professionals use Gestational Age to date pregnancy. The Gestational Age refers to how long it has been since the first day of the mother’s last menstrual period.
During each week of pregnancy the baby develops and grows in new and exciting ways.
2 Weeks* (Conception): Conception usually takes place approximately two weeks from the beginning of the mother’s last menstrual period. This is when the egg and sperm unite to form a single cell. This cell contains all the genetic information for every detail of the newly created life – including, gender, eye & hair color, skin tone, and the intricate lines of the fingerprints.2
21 days/5 Weeks (The Heart & Brain): The heart is the first organ to function and begins to beat 21 days after conception (which is five weeks after the mother’s last menstrual period began). The first signs of brain development are also evident at this stage of development.3
8 Weeks: At eight weeks, the embryo can respond to touch by reflex.4
10 Weeks: For the first time, the brain can make the muscles move on purpose.5
For more information about fetal development, download The First 9 Months brochure.