To better understand the changes your body goes through during the last trimester and labor, it is helpful to be familiar with basic anatomy. Open the activity on the right to compare your body before pregnancy to your body at 37 weeks. You'll see how your body adjusts in amazing ways to support your growing baby. Then, play the video to learn about pregnancy anatomy from inside the womb.

open activity Activity: Comparative Anatomy


Comparative Anatomy

Mouse over each word to highlight organs

play video Anatomy: Take a 3D look inside pregnancy.

view text Take a 3D look inside pregnancy.

(Narrator) Seeing the anatomy of pregnancy will help you understand the physical changes that occur during pregnancy, labor, and birth. This image shows the inside of a pregnant woman with her baby at full term. (Narrator) The baby lives inside of her mother’s uterus. This is a strong, balloon-shaped muscle that will contract during labor. The bottom part of the uterus is the cervix. A mucous plug fills the cervix and prevents outside germs and bacteria from reaching your baby. Below this is the vagina, which is also called the birth canal because it will be your baby’s passageway into the world. (Narrator) The placenta is an organ created by the mother’s body just for pregnancy that grows into the wall of the uterus. The placenta makes pregnancy hormones, carries oxygen and nutrients from mother to baby, and removes waste from the baby’s blood. The umbilical cord carries blood back and forth between the placenta and the baby. Growing out from the placenta is the amniotic sac, which is also known as the bag of waters. The water inside the sac is called amniotic fluid. It cushions the baby and keeps her warm.

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Fetal Development: These amazing 4D ultrasound images show you how babies move in the womb.

Fetal Development
view text These amazing 4D ultrasound images show you how babies move in the womb.

4D ultrasound images like this one give us a special glimpse at what babies can do in utero during the third trimester. As this baby rubs her eyes, you can see that her facial features are already unique. In this next ultrasound, you can see this baby lick his arm. His mother probably just ate a sugary snack that he's tasting. In this one, the baby's practicing how to move her hands and fingers. Perhaps she'll give mom a little jab by accident. While babies move around and explore the womb, important fetal development continues right up until birth: their lungs mature, their brains are wired for thinking, and they gain the body fat needed to stay warm outside of the womb.

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