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Week 12 of Pregnancy: What's Going On Inside


By week 12, you can now hear a fetus's heartbeat with a Doppler heart monitor.

Wondering what a fetus looks like at 12 weeks? It is now about the size of a lime.

How a fetus is changing

Here are some important changes that happen around this time.

  • By 10 weeks of pregnancy, an embryo has nearly all of the body structures that adults have. Its brain is now more complex. After this point, we call it a fetus.
  • During this month, the fetus's limbs, hands, and head start to move. Eyelids cover their eyes, and their fingernails are starting to grow.
  • At the end of this month, fetuses start a big weight gain.


Current as of: July 10, 2023

Author: Healthwise Staff
Clinical Review Board
All Healthwise education is reviewed by a team that includes physicians, nurses, advanced practitioners, registered dieticians, and other healthcare professionals.