Articles
Fetal development: The first trimester
Week 5: Hormone levels increase
Week 7: Baby's head develops
Week 8: Baby's nose forms
Week 9: Baby's toes appear
Week 10: Baby's elbows bend
Week 11: Baby's genitals develop
Week 12: Baby's fingernails form
Content
Weeks 1 and 2: Getting ready
Week 3: Fertilization
Week 4: Implantation
Week 5: Hormone levels rise
Week 6: The neural tube closes
Week 7: The head develops
Week 8: The nose forms
Week 9: Toes appear
Week 10: The elbows bend
Week 11: Genitals develop
Week 12: Fingernails form
Week 7: Baby's head develops
Week 8: Baby's nose forms
Week 9: Baby's toes appear
Week 10: Baby's elbows bend
Week 11: Baby's genitals develop
Week 12: Baby's fingernails form
Content
Weeks 1 and 2: Getting ready
Week 3: Fertilization
Week 4: Implantation
Week 5: Hormone levels rise
Week 6: The neural tube closes
Week 7: The head develops
Week 8: The nose forms
Week 9: Toes appear
Week 10: The elbows bend
Week 11: Genitals develop
Week 12: Fingernails form
Content
By Mayo Clinic Staff
You're pregnant. Congratulations! As your pregnancy goes on, you may wonder how your baby is growing and developing. Use this information to follow along with what's happening week by week during the first 12 weeks of pregnancy, called the first trimester.
