Newly discovered heart murmur in 34 year old. What does it mean?

I am 34 years old and last year on my annural Gyn appt my doctor said "has anyone ever told you that you have a heart murmur" after listening to my heart. And of course I have never had a heart murmur before. Well she said that I should just go see my primary doctor to see if he wants to do further testing. Well I have a busy schedule and did not go see a doctor as she suggested. I did NOT have any symptoms from the heart murmur. Well a year later my husband and I decided to have another child and now that I am 14 weeks pregnant I have noticied that I am short of breath and now concerned about the heart murmur. Are heart murmurs usually innocent or is this something that I could wait to get checked out until after my pregnancy.