-
Weeks 1-2
None -
Weeks 3-4
-Conception
-Zygote turns into blastocyst and
travels down the fallopian tube
-Rapid cell division begins
-Blastocyst implants in uterus lining
during week 4 and becomes and
embryo -
Weeks 5-6
•Neural tube closes; brain and spinal cord will form
•Heart, organs, and bones start to form
•Develop head and trunk
•Arm and leg limb buds appear
•Brain begins development
•Eyes and ears begin to form
•Heart continues to develop, and beats a regular rhythm
•Baby is 1/6 inch long -
Weeks 7-8
•Brain and face shape begin growing
•Four-chamber heart
•Lungs begin to form
•Fingers and toes start to form
•Ear begins to develop internally
•Lip and nose have formed
•Trunk and neck begin to straighten
•Baby is about ½ inch long
•All major organs are formed -
Week 10
•Head is half the size of the baby
•All body parts are present
•Eyes, ears, arms, and legs are
identifiable
•Baby is 1 ¼ inches long -
Week 11
•Genitals develop
•Head is about half of the length of
baby
•Teeth buds form
•Baby is about 2 inches in length and
weighs about 1/3 ounce -
Week 12
•Fingernails grow
•Face has more defined profile
•Intestines are in the abdomen
•About 2 ½ inches in length and
weighs about ½ ounce -
Week 14
•Baby’s sex will become apparent
•Baby can swallow and make urine
•Baby is about 3 ½ inches in length and weighs about 1 ½ ounces -
Week 16
•Baby is moving but mom cannot feel
it
•Baby is about 4 ½ inches in length
and weighs about 4 ounces -
Week 18-19
•Baby begins to hear
•Digestive system works
•Vernix caseosa covers the baby -
Weeks 20-21
•Regular sleep and wake patterns
•All organs and structures formed
•Breathing movements occur but are underdeveloped
•Covered in Lanugo
•May begin to suck thumb
•Baby is about 6 1/3 inches in length and weighs about 11 ounces -
Week 22
•Has nails, fingerprints, eyebrows,
lashes, and possibly some hair
•More active
•Heartbeat heard with a stethoscope
•Lowest limit of viability (survival
outside the mother)
•Baby is about 7 ½ inches in length
and weighs about 1 pound -
Week 24
•Wrinkly skin, translucent and pinkish
red
•Lung development
•Regular sleep and wake patterns
•Baby is about 8 inches in length and
weights about 1 1/3 pounds -
Weeks 28-29
•Eyes begin to partially open and
close
•Central nervous system directs
breathing and body temperature
control
•Lungs are capable of breathing air
•Baby begins to kick and stretch
•Baby is about 10 inches in length
and weighs about 2 ¼ pounds -
Week 31-32
•Finished most major development
•Rapid weight gain begins
•Lanugo starts to fall off
•Baby is about 11 inches in length and weighs about 3 ¾ pounds -
Week 34
•Continues to grow fingernails and
toenails
•Develop breathing motion
•Responds to light
•Skin is pink and smooth
•Baby is about 12 inches in length
and weighs about 4 ½ pounds -
Week 36-37
•Takes up most of the amniotic sac
•Starts to turn head down to prepare
for labor
•Baby is about 13 ½ inches in length
and weighs about 6 pounds
•Will continue to gain about ½ pound
a week until delivery -
Week 38-40
•Brain, lungs, and liver still developing
•Brain will double in size between week 35 & 39
•Lung development during last few weeks helps with fewer complications after birth
•At week 39, baby is considered full term
•Weight gain helps with temperature control once born