Your baby's development
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Six to eight weeks- Fetus is about ½ an inch long
- Spinal cord, nervous system and gastrointestinal systems (stomach and intestines) are developing
- Sense of hearing and lungs are developing
- Eyes, ears, nose tip and tongue are forming
- Arms and legs are present, with slightly webbed fingers and toes
- Placenta and umbilical cord are forming
Nine to 10 weeks- Fetus is about 1 inch long
- Fingers are present
- Fetal heartbeat may be detectable
- External genitals are developing
- Fetus moves constantly
11 to 12 weeks- Fetus is about 2 inches long and weighs ½ ounce
- Face begins to look more human: eyes are closer together, ears more to the sides of head
- Fetus starts secreting urine
- Brain continues to develop as nerve cells multiply
13 to 14 weeks- Fetus is about 3 inches long and weighs 1 ounce
- Fetus can smile, frown and move fingers and toes
- Fingernails are forming
- Taste buds are developed
- Gender is detectable
- Placenta development is complete, with a full exchange of nutrients and waste products
15 to 17 weeks- Fetus is about 5 inches long and weighs 4 ounces to 5 ounces
- Body now is growing faster than the head
- Fetus can suck its thumb
- Fetus swallows amniotic fluid
- Heart pumps about 25 quarts of blood each day
- Bones start to form
- Body starts to cover with lanugo (soft, downy hair)
20 weeks- Fetus is about 8 inches long and weighs about 11 ounces
- Body is completely covered with lanugo
- Eyebrows and eyelashes start growing
- Nails appear on fingers and toes
- Fetus is more active due to increased muscle development
- Heartbeat can be heard with a stethoscope
- Quickening (when the mother can feel the fetus moving) can occur
24 weeks- Fetus is about 11 inches long and weighs about 1 pound, 10 ounces
- Eyebrows and eyelashes are well formed
- Eyes are fully developed
- Fetus has hand reflexes and startle reflexes
- Footprints and fingerprints are forming
- Alveoli (air sacs) in lungs are forming
25 to 28 weeks- Fetus is about 15 inches and weighs about 2 pounds, 11 ounces
- Rapid brain development occurs
- Nervous system develops enough to control certain body functions
- Eyelids open and close
- Respiratory system is immature, but developed enough for gas exchange
- Baby born at this time may survive, but complication rates and death rates are high
29 to 32 weeks- Fetus is from 15 inches to 17 inches long and weighs about 4 pounds, 6 ounces
- Body fat rapidly increases
- Lungs are not fully mature, but rhythmic breathing movements occur
- Bones are fully developed, although they are soft and pliable
- Fetus starts to store iron, calcium and phosphorus
36 weeks- Fetus is about 16 inches to 19 inches long and weighs about 5 pounds, 12 ounces, to 6 pounds, 12 ounces
- Lanugo starts to disappear
- Body fat continues to increase
- Fingernails grow to end of fingertips
- Baby born at this time has good chance of survival, but may need medical intervention and care
37 to 40 weeks- Fetus may be 19 inches to 21 inches long and weigh about 6 pounds to 8 pounds, 8 ounces; it is considered full-term at 37 weeks
- Lanugo is gone except for upper arms and shoulders
- Fingernails grow beyond fingertips
- Small breast buds present in both genders
- Hair on head is coarse and thick