My ultra sound at 20 weeks: ac only 16th percentile; head 35 percentile. follow up at today at 28 wks now ac is 31 but head is 8. so worried about 8. ?

More information: The ultrasound results are indeed worrisome but to say how worrisome would require more information. A consult with a maternal-fetal medicine specialist ( an Ob with special training in high risk pregnancies) would be advisable to give you a better idea what is going on and provide the best management. My best wishes to you and the baby.