Week 13: Bones start to harden

Week 14: Red blood cells form

Week 15: Bone development continues

Week 16: Eyes move

Week 17: Toenails develop

Week 18: Hearing develops

Week 19: A protective coating forms

Week 20: The halfway point

Week 21: Baby can suck a thumb

Week 22: Hair becomes visible

Week 23: Fingerprints and footprints form

Week 24: Skin is wrinkled

Week 25: Baby responds to your voice

Week 26: Eyebrows and eyelashes form

Week 27: Second trimester ends