Uterine fibroids do not shrink in mid-pregnancy. Fibroids are a common type of benign tumor that grow slowly and have relatively clear borders. In pregnant patients, fibroids grow a little faster than usual, but they usually do not have any serious consequences for pregnancy. For patients with fibroids, those with small fibroids and no symptoms may not need treatment and regular ultrasound checkups are sufficient. It is generally considered that patients with fibroids over 5 cm or with more obvious symptoms need to be surgically removed.