Now that your baby-to-be is fully formed, all of her various organs and structures are gaining definition and growth. For example, her kidneys are beginning to function this week, Nutrients are provided by the placenta and delivered through your baby's umbilical cord. Her little body also gets rid of liquid waste through the umbilical cord. Later, some of baby-to-be's urine might also be secreted into the amniotic fluid surrounding her, but this is normal and doesn't harm the baby.
Your baby can swallow by now, and he might even get the hiccups! He's a whopping three 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.
All of the major organ systems have finished forming by the end of your first 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.
Baby's various body systems are also beginning to work, although at a very basic level. Her nervous system is establishing connections between the brain and the developing baby's muscles. Along with jerky motions of her legs and arms, she might try more complex movements, such as squinting her eyes, moving her delicate fingers or toes, even sucking her thumb. Her reproductive system is also continuing to develop, but your sonographer would be hard-pressed to find and identify the gender with an ultrasound. With all of her systems becoming stronger and more developed, you might be able to hear your baby-to-be's heartbeat during your normal prenatal office visit. Your health care provider will use a special instrument, called a Doppler, to pick up baby's heartbeat by passing the device over your abdomen.
BPD (biparietal diameter): A measurement of the fetus' head. Used to determine the width of the head, the sonographer will measure from just above one ear to the other.
Images courtesy of the American Institute of Ultrasound in Medicine (AIUM.org)