<prompt> Periconceptional use of the following agent leads to reduced incidence of neural tube defects?Folic acidIronCalciumVitamin A  <response>: Folic acid supplementation 4mg a day staing 4 weeks prior to conception up to 12 weeks of pregnancy is advised.This can reduce the incidence of neural tube defects.Reference: DC Dutta;s Textbook of Obstetrics, 8th edition, page no:472 