<s>[INST] After my 20 week ultrasound there were concerns about baby measuring small. Limbs (sorry, I don t recall the exact term) were in the 4th and 5th percentile, HC was 11th, and BPD was measuring in the 1st percentile. I was sent for a follow up ultrasound at 26 weeks. The numbers improved slightly with the limbs in the 8th and 9th percentile, HC was 18th, and BPD was at 4. My doctor is concerned, particularly with the BPD and has sent me for some tests and is referring me to a specialist. He also said I ll have more ultrasounds to monitor. Im looking for thoughts on what this could be. I just want to be prepared when I do get results back. I would rather worry over nothing than not be worried and have it turn out serious. [/INST] Hello and Welcome to ‘Ask A Doctor’ service. I have reviewed your query and here is my advice. The findings you shared are suggesting intrauterine growth retardation. In this condition there growth parameters do not increase as they should according the dates. One needs to look for the cause. Serial ultrasound scans are done to ascertain if growth is there or not. In case no growth is seen after specific time then doctor usually suggests termination of pregnancy. However, this decision depends upon strong evidence of no growth. Hope this answers your question. If you have additional questions or follow up questions then please do not hesitate in writing to us. Wishing you good health. </s>