Fibroid pain during pregnancy occurs when noncancerous growths in the uterus expand or undergo changes due to increased hormones. Many women experience symptoms such as pelvic pain, abdominal pressure, backache, or cramp-like discomfort, especially in the second and third trimesters. In some cases, pain results from fibroid degeneration, when the growth outgrows its blood supply.
https://www.usafibroidcenters.com/blog/how-fibroids-affect-each-trimester-of-pregnancy/