Prenatal Development (timeline)

week 6-7

• heart beats at regular rhythm

• arm and leg buds

• umbilical cord develops

• tissue that develops into vertebra and bones appears

• blood moves through blood vessels

• start of eyes and ears

• brain = 5 areas + some cranial nerves

week 8

• beginning formation of the lungs

• further brain development

• arms and legs lengthen

• foot and hand areas are distinguishable (have digits but may still be webbed)

week 9

• nipples and hair follicles

• elbows and toes appear

• all essential organs have begun to form

week 10

• rotation of intestines

• facial features continue to develop

• eyelids start to develop

• external ear begins to take final shape

• at the end of this week the embryo is considered a fetus

week 11-14

• fetus begins movement

• fetus = 3.2 in

• head = half of body size

• eyelids close and do not reopen until week 28

• tooth buds appear for baby teeth

• limbs are long and thin

• fetus can make a fist

• genitals appear

• RBCs are produced in liver

week 15-18

• fine hair on head (called lanugo)

• fetus moves and stretches more

• fetus = 6 in

• transparent skin

• more muscle tissue and bones develop

• bones are harder

• sucking motions are made with mouth

• liver and pancreas produce their fluid secretions

week 19-21

• mother feels quickening (when mom can feel baby’s first movements)

• fetus can hear

• more active in womb (“climbs uterine wall”)

• by end of these weeks baby can swallow

week 22

• fetal heartbeat can be heard with stethoscope

• fetus = 8 in

• lanugo hair covers entire body

• meconium (baby stool) is made in intestinal tract

• eyebrows and lashes appear

• nails appear on fingers and toes

• mom can feel fetal movements

week 23-25

• bone marrow begins to make blood cells

• lower airways of baby’s lungs develop

• baby begins to store fat

week 26

• alveoli (air sacs) forming in lungs

• fetus = 11.2 in

• fetus weighs 1lb 10oz

• eyebrows and eyelashes are well formed

• all eye components developed

• fetus has grasp and startle reflex

• footprints and fingerprints forming

week 27-30

• respiratory system begins to develop surfactant for gas exchange

• baby born at this time may survive, but complication and death rates remain high

• fetus = 15 in

• fetus weighs 2lbs 11oz

• rapid brain development

• nervous system can control some body functions

• eyelids open and close

week 31-34

• rapid increase in amount of body fat

• rhythmic breathing but lungs are not fully mature

• bones are fully developed but still soft and pliable

• fetus begins storing iron, calcium, and phosphorus

• baby = 15-17 in

• fetus weighs 4lbs 6oz

week 35-37

• baby born at this stage has high chance of survival but may require additional medical interventions

• baby weighs 5.5lbs

• 16-19 in long

• fetus keeps gaining weight but not length

• skin is less wrinkled b/s fat forms beneath skin

• definite sleeping patterns

• heart and blood vessels developed completely

• muscles and bones are fully developed

week 38-40

• full term = 38 weeks

• 19-21 in long

• lanugo gone except on upper arms and shoulders

• fingernails reach end of fingertips

• small breast buds for both males and females

• head hair is course and thicker

in the __ week of pregnancy it has been 38 weeks since ________ and baby can be born any day

40th; conception

baby born at __ weeks has a high survival rate but may require additional interventions

36