Is there something wrong with my baby? My ob is sending me to mfm.

Not necessarily. In many practices it is customary for the OB doc to follow the pregnancy and the mfm to do the ultrasounds as a routine. The mfm can also be there for the OB if there is a problem so best to ask your OB to sort it out.
Pregnancy and MFM. All pregnancies are screened by an mfm(maternal fetal medicine specialists) at least twice during the duration of pregnancy.Once between 13 weeks for nt screen(down's syndrome testing) and once between 20-22 weeks for ntd screen(neural tube defect).At this second screening we check for other anomalies of the fetus as well.Sometimes if the fetal growth is slow, mfm exams may be required additionally.