What happens during the first trimester?
At four weeks:
- Your baby’s brain and spinal cord have begun to form.
- The heart begins to form.
- Arm and leg buds appear.
- Your baby is now an embryo and smaller than a grain of rice.
At eight weeks:
- All major organs and body structures have started to form.
- Your baby’s heart beats with a regular rhythm
- The arms and legs grow longer, and fingers and toes have started to form.
- Your baby’s sex organs have begun to form.
- The eyes have moved forward on the face and eyelids have formed.
- The umbilical cord can easily be seen.
- At the end of eight weeks, your baby looks more like a human and is almost 1 inch long.
At 12 weeks:
- Nerves and muscles are starting to work together and your baby can make a fist.
- Your baby’s sex organs show on the outside, baby’s sex can be seen soon with an ultrasound.
- The eyelids close to protect the eyes.
- Your baby is about 3 inches long.
Source: Womenshealth.gov