Prepregnancy counselling is efficient in cases of chronic maternal disease, selection of medication and avoiding bad life habits. A new policy is the use of folic acid in the periconceptional period for the purpose of reducing the chance of having a baby with neural tube defects (NTD). Research in progress at the Department of Obstetrics and Gynaecology in Nijmegen, the Netherlands, is presented demonstrating that a derangement of methionine-homocysteine metabolism could be the underlying mechanism of pathogenesis and prevention with folic acid. Such derangement was found in ± 20% of cases with NTD, recurrent miscarriage and placental infarcts (abruption) and offers new possibilities for primary prevention in three major areas