Detect the heartbeat of the baby

Hi! To i went to my regular check up. When the nurse want to detect the heartbeat of the baby, she managed to do so but she said it is the heartbeat from the umbilical cord or tali pusat. Is it okay? It happened two times in a row from previous check up and today’s check up. Is it normal? #helpme #firsttimemom #imscaredifanythingmighthappen