The Inside Story: Your Baby in Week Twelve

Baby is three inches long this week! Find out more about her growth and development during your 12th week of pregnancy.

Your baby can swallow by now, and he might even get the hiccups! He's a whopping 3 inches long, and his head, which was half the size of his body last month, is now just a third as big as the rest of him. He's also less hunched over. His face is almost fully formed, and his nose, eyelids, and ears are almost completely developed. He's even got an upper lip.

Blood has started to pump through your baby's umbilical cord, carrying nutrients and oxygen from your body through the placenta to support your baby. The umbilical cord also works in reverse to rid your body of the baby's waste products now that his kidneys are excreting urine.

All of the major organ systems have finished forming by the end of your 1st trimester, so now they only need to grow. Your baby has opposable thumbs too, and his motions are more purposeful. In fact, some researchers say they can detect variations in personality even this early, such as whether your baby will be active or calm, a thumb sucker or not. Most of his motions right now are reflexes, but his muscles are starting to respond to his brain signals; he can kick and curl his toes. If you could prod your baby's hands right now, they would probably close because of reflex. He'll be holding your finger with a good, firm grip before too long.

Originally published in You & Your Baby: Pregnancy.

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