The end of the twelfth week of pregnancy marks the end of the first trimester. Your baby is now almost 2.5 inches long (6.1cm) when measured from crown to rump, and weighs between 0.3 and 0.5 ounces (9 to 13g).
Your baby's fingers and toes have separated and are getting longer. Your baby can open and close its mouth and drinks amniotic fluid which it passes out as urine. Its head is becoming more rounded, though it is still large in proportion to its body. It has eyelids.
You can now hear your baby's heartbeat with a Doppler Ultrasound device!
Your baby continues to grow rapidly and has doubled in size in the last three weeks alone.
The face is beginning to look more human, and all body structures are present with a few refinements still in progress. Fingernails and toenails begin to develop this week.
Your baby's muscles are sufficiently developed to allow for involuntary movements at this time. The messages which control your baby's movements are sent from the spine, rather than the brain, which is not yet sufficiently developed.