When can you see a baby in ultrasound?

An ultrasound, also known as a sonogram, can detect a pregnancy as early as 5 weeks from the first day of a woman's last period. An ultrasound uses sound waves to create images of the inside of the body. In early pregnancy, an ultrasound can show the gestational sac, which is a small fluid-filled sac that contains the developing embryo. The embryo can be seen as a small dark spot within the gestational sac. As pregnancy progresses, the ultrasound will be able to show more details of the baby's development, such as the head, body, and limbs.