4 Weeks Pregnant: Ultrasound & Early Pregnancy – What to Expect

First, let's clarify something. It is not possible to see a baby on an ultrasound at 4 weeks of pregnancy. An embryo at that stage of development is a cluster of cells that is too small to be detectable by ultrasound. It would likely be another week or two before an experienced sonographer could positively identify a fetal pole and yolk sac and confirm a viable pregnancy.