Pregnancy Weekly Guide
[Week 5 Baby] The fetus is resting in the gestational sac.
The gestational sac is visible on ultrasound. You can also see the heart, which starts to beat about 21 to 22 days after fertilization.
However, the sac may not be visible on ultrasound at week 5, so don't worry if you don't see one this week. You can get a doctor's letter confirming pregnancy once the sac is confirmed inside the uterus. This is also when the embryo loses the tail and grows into a more human-like fetus.