The fibroids that grow inside the uterine cavity are called submucosal fibroids, which can lead to miscarriage and premature birth, and even to abnormal development of the child if the fibroids in the uterine cavity are too large. Most fibroids between the muscles of the uterus have no effect on pregnancy, but if the placenta is in the location of the fibroids, they may increase in size during delivery or in the middle or late stages of pregnancy, leading to a crisis of placental abruption. There is another type of fibroid that grows outside the uterus, called subplasmic fibroids, which usually has no effect on pregnancy. In any case, if a pregnancy is combined with fibroids, the majority of pregnancies are not affected as long as the fibroids are monitored closely during pregnancy and the size of the fibroids is observed. There are some pregnant women who need to have a cesarean section for other reasons, and the doctor can remove the fibroids during the cesarean section.