What happens during the second trimester?

At 16 weeks:

  • Muscles and bones are still forming, making a more complete skeleton.
  • Skin begins to form.
  • Your baby makes sucking motions with the mouth.
  • Your baby is about 4 to 5 inches long and weighs almost 3 ounces (about as much as a small apple).

At 20 weeks:

  • Your baby is more active and you may start to feel movement.
  • Your baby is covered by a fine hair called lanugo (luh-NOO-goh) and a waxy coating called vernix. These protect the skin as it grows.
  • Eyebrows, eyelashes, fingernails, and toenails have formed.
  • Your baby can hear and swallow.
  • Your baby is about 6 inches long and weighs about 9 ounces.

At 24 weeks:

  • Taste buds form on your baby’s tongue.
  • Footprints and fingerprints have formed.
  • Real hair begins to grow on your baby’s head.
  • The lungs are formed, but do not work.
  • Your baby sleeps and wakes regularly.
  • Your baby is now about 12 inches long and weighs 1.5 pounds.