Measuring big/ahead?

hlhindin

What exactly does this mean?  I had my 35-week appointment today and our little girl is measuring almost 38 weeks.  I assumed that meant that she is just big, but three different family members have commented that they interpret that to mean she'll come early.  I didn't ask at the doctor's office, because it didn't occur to me to interpret it that way until other people started chiming in.  Just to clarify, it's simply a size thing...er, right?

TIA!