Possibly under grown baby?

Shaina
I went to the doctor today for my monthly check up.  I'll be 25weeks tomorrow.  Doc says my belly is measuring in at 24-241/2 weeks.  He had a difficult time finding the baby using Doppler.  After about 5mins he found him.  He ordered an ultra sound to ensure the baby is growing at an appropriate rate.  This kinda concerns me.  I don't go until the 15th.  Has anyone else had this issue?  What was the out come?  This is my first pregnancy