Down syndrome is a chromosomal abnormality associated with genetics. For your situation, it is recommended to undergo amniocentesis, a more accurate testing method to further determine if the fetus has Down syndrome. Additionally, it is suggested to have a 4D ultrasound around the 24th week of pregnancy to check for any abnormalities in the fetus’s appearance and internal organs. If a neural tube defect is diagnosed, it may lead to severe malformations such as intellectual disability and disabilities in the newborn.

If you undergo a Down syndrome screening around the fourth and a half month of pregnancy and the results indicate a high risk of neural tube defects, further examination is needed. Options include DNA testing or amniocentesis.