<prompt> What is the best preventive measure for neural tube defects?Vitamin B12 supplementation to motherFolate supplementation to motherBCG vaccination at birthUSG in 2nd trimester  <response>: Ans. is b i.e., Folate supplementation to mother Neural tube defectso NTDs account for most congenital anomalies in CNS. It results from failure of neural tube to close spontaneously between 3rd-4th week of in utero developmento NTDs have multiple etiological factors :- Maternal diabetes Maternal exposure to alcohol, radiation, valproate, carbamazepine Zinc and folate deficiency Trisomy 13 and 15 Maternal malnutrition is an important risk factor for development of NTD. There is decreased maternal folatelevels in NTD affected pregnancies. Periconceptional folic acid supplementation decreases the occurrence of NTDo NTDs allow excretion of fetal substances like alpha-fetoprotein and acetylcholinesteraseinto amniotic fluid, which are used as prenatal biochemical markers for diagnosis 