Does a normal biparietal diameter with slightly small head circumference have any impact?

Generally, whether a smaller-than-normal head circumference with normal biparietal diameter has any impact needs to be evaluated based on specific data and gestational age. Detailed analysis is as follows:

If the head circumference is less than two weeks' difference from the expected value and other fetal growth parameters are normal with regular fetal movements, significant adverse effects are unlikely. This may result from genetic factors—parents with smaller head circumferences may pass this trait to the fetus. It could also stem from measurement errors or individual variations in fetal head development. If follow-up ultrasounds show normal growth velocity of the head circumference, excessive concern is usually unwarranted; regular prenatal monitoring suffices.

If the head circumference is more than two weeks below the expected value, or if it is accompanied by ventriculomegaly or abnormal fetal movements, close attention is required. This may indicate abnormal brain development, chromosomal abnormalities, intrauterine hypoxia, or inadequate nutritional supply, which could potentially affect neurological development over time. Further diagnostic tests are necessary to determine the underlying cause and initiate appropriate interventions.

Pregnant women should maintain a balanced diet, consume adequate high-quality protein and DHA, adhere to a regular sleep schedule to avoid fatigue, stay emotionally positive, and strictly follow medical advice for prenatal checkups and necessary care.