SPECIAL OFFER: - Limited Time Only!
(The ad below will not display on your printed page)

First Trimester: Images of Your Developing Baby

Do you know what to expect in the first trimester of pregnancy? We've partnered with the American Institute of Ultrasound Medicine (AIUM), Johns Hopkins, and the March of Dimes to create this unique peak into Baby's development inside the womb during the first trimester. These images reveal all the intricate details of your baby's growth. While most women normally receive one or two ultrasounds during pregnancy, this slideshow of the first trimester of pregnancy gives you a look at each week of development.
Week 5 Week 5 of Pregnancy

Fetal Size: 1/18 to 1/16th of an inch (about the size of the pen dot).

Fetal Development Milestones: Cells that will form the heart and the central nervous system are developing.

What You're Seeing: The dark area is the fluid filling the gestational sac. Eventually, this fluid will be replaced by a sac containing the amniotic fluid your baby-to-be will live in for the next few months. The white circle within the fluid is called the yolk sac. Before the placenta is fully formed, the yolk sac plays a role in providing all the nutrients your baby-to-be needs to grow. Adjacent to the yolk sac, little + marks show a very early embryo. The sonographer measures the length of the embryo (the crown-rump length or CRL) to confirm or revise the due date estimated from your LMP, or to evaluate the embryo's growth.