How Your Baby Grows
To get a rough idea of when your baby is due visit Due Date Calculator (SOGC).
Your due date is a best guess – most babies are born within two weeks before or after your due date.
The FIRST trimester weeks 1 to 13
By the end of the first trimester:
- the placenta, the cord and all of baby’s organs have formed and are working together.
- baby’s heart is beating.
- the spine and bones are taking shape.
- baby is using muscles to move and kick, but you won’t feel movement yet.
- the face is forming and includes ears, a nose and eyes which are closed.
- the arms, legs, fingers and toes have appeared – fingerprints are present
- the brain is growing quickly.
- baby is 7 to 10 cm (3 to 4 inches) and weighs 28 grams (1 ounce).
The SECOND trimester weeks 13 to 28
By the end of the second trimester:
- baby’s eyes can open, eyebrows and lashes appear.
- the heartbeat can be heard by your health care provider.
- the external genitals are well developed by the end of the 14th week – an ultrasound can show if you are having a boy or a girl.
- you will be able to feel baby moving (16-20 weeks).
- tooth buds develop inside the gums.
- soft, fine hair is growing on the body.
- a white coat (vernix) covers baby’s body to protect it.
- baby’s senses develop – can hear your voice (18 weeks) and open eyes.
- baby is about 36 cm long (14 inches) and weighs 1 kilogram (2 pounds).
The THIRD trimester weeks 29 to 40
By the end of the third trimester:
- baby can suck on its thumb and swallow.
- the skin becomes less wrinkled as baby gains weight more quickly.
- baby won’t be doing somersaults but you should still feel frequent movement.
- baby has periods of sleep and wakefulness.
- baby can see and will turn to a bright light.
- the lungs and brain mature.
- baby has stored iron, other nutrients, and antibodies from mom.