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Week 12 of Pregnancy: What's Going On Inside

British Columbia Specific Information

If you have any questions or concerns about pregnancy, labour and baby care speak with your health care provider or contact HealthLink BC at 8-1-1 to speak with a registered nurse anytime of the day or night, any day of the year, or a pharmacist from 5:00 p.m. to 9:00 a.m.

You can also read Baby's Best Chance (PDF 14.88 MB), a parent’s handbook on pregnancy and baby care.

Topic Contents

Topic Overview

Congratulations, you've made it through your first trimester! You can now hear your baby's heartbeat with a Doppler heart monitor. That can be very exciting.

Inside your uterus, an important organ called the placenta has formed. The placenta's main job is to give your baby oxygen and nutrients through the umbilical cord.

Wondering what your baby looks like now? As you enter the fourth month of pregnancy, your baby is about the size of a plum. Average baby length is 61 mm (2.4 in.).

How your baby is changing

Here are some of the important facts and developments around 12 weeks.

    • When you are 10 weeks pregnant, your fetus has nearly all of the body structures that an adult has. The brain is now more complex.
    • This month, the tiny fetus starts moving the head and jaw, grasping, moving the tongue, and stretching. Eyelids are covering the eyes, and fingernails are starting to grow.
    • At the end of this month, the fetus starts a big weight gain.

Credits

Adaptation Date: 9/17/2021

Adapted By: HealthLink BC

Adaptation Reviewed By: HealthLink BC