Fetal head is small, the doctor said maybe the fetal head deformity

29 weeks pregnant today, went to hospital to check the results of B-BPD6.7CM, HC26.5cm, FL5.5cm, AC24.0cm Palace high 29, the doctor said fetal head is small, maybe I'm worried about fetal head deformity

Fetal malformations, maternal surface will not have any particular symptoms, but there may be a precursor to abortion.
Need to be able to have special medical diagnosis confirmed, with the living conditions of pregnant women to see if can find out the reasons for teratogenicity.