The third stage of development is called embryonal. It lasts from two months through birth.

The third stage of development is the fetal stage, which lasts from two months (eight weeks) through birth. This is supported by the following sources: 1. The American Pregnancy Association - "The fetal stage of development begins at the end of the eighth week after conception and lasts until the birth of the baby." (https://americanpregnancy.org/while-pregnant/stages-of-development/) 2. Kids Health from Nemours - "Your baby is now considered a fetus and is growing in size and maturity. This stage of development lasts from the 9th week of pregnancy until birth." (https://kidshealth.org/en/parents/stages.html) 3. Healthline - "From the ninth week of gestation until delivery, the baby is known as a fetus." (https://www.healthline.com/health/pregnancy/stages-of-development#1)