Title: Fetal development: The 1st trimester - Mayo Clinic
Headings: 
Fetal development: The 1st trimester
Weeks 1 and 2: Getting ready
Week 3: Fertilization
Week 4: Implantation
Week 5: Hormone levels increase
Week 6: The neural tube closes
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
Products and Services

Content: The trunk and neck begin to straighten. By the end of this week, your baby might be about 1/2 inch (11 to 14 millimeters) long from crown to rump — about half the diameter of a U.S. quarter. Week 9: Baby's toes appear
Open pop-up dialog box
Fetal development seven weeks after conception
Close
Fetal development seven weeks after conception
Fetal development seven weeks after conception
By the end of the ninth week of pregnancy — seven weeks after conception — your baby's elbows appear. In the ninth week of pregnancy, or seven weeks after conception, your baby's arms grow and elbows appear. Toes are visible and eyelids form. Your baby's head is large but still has a poorly formed chin. By the end of this week, your baby might be a little less than 3/4 inch (16 to 18 millimeters) long from crown to rump — the diameter of a U.S. penny. Week 10: Baby's elbows bend
Open pop-up dialog box
Fetal development eight weeks after conception
Close
Fetal development eight weeks after conception
Fetal development eight weeks after conception
By the end of the 10th week of pregnancy — eight weeks after conception — your baby's toes and fingers lose their webbing and become longer.