HI,
   I understand your query & concern.   
Fibroid is a 
tumor from uterine muscles . It tends to grow in early weeks of 
pregnancy when 
estrogen is in high amount in mother's circulation- but later on it hardly interferes with pregnancy.
    * when placenta is attached near fibroid,  though there is small chance of blood supply to baby, there is chance of placental separation& early induction of delivery may become essential to save life.
   * I would advise you to be in contact with your gynecologist through out your pregnancy . You will need repeated scans, blood investigations to assess  the pregnancy  condition. strictly follow the advise given. The management would depend on placental position & other developments with advance of pregnancy.
  -  Should consult your doctor immediately in case of-abdominal & 
back pain, uterine contractions, continuous uterine contraction without relaxation, vaginal bleeding.
  - Be ready to terminate pregnancy if your doctor advises so.
   Thanks..