When Does Embryonic Period Begin?

After conception, your baby begins a period of dramatic change known as the embryonic stage. This stage runs from the 5th through the 10th week of pregnancy. During this stage, the baby is called an embryo. There are numerous changes that occur during the embryonic stage.

What does the embryonic period begin with?

The beginning of the third week after conception marks the start of the embryonic period, a time when the mass of cells becomes distinct as a human. The embryonic stage plays an important role in the development of the brain. Approximately four weeks after conception, the neural tube forms.

How long is the pre-embryonic period?

The first 2 weeks of prenatal development are referred to as the pre-embryonic stage. A developing human is referred to as an embryo during weeks 3–8, and a fetus from the ninth week of gestation until birth.