AnencephalyFolic AcidVaccinium myrtillusCerealsFood, FortifiedSpinal DysraphismSpina Bifida OccultaNeural Tube DefectsDietEncephalocelePregnancyCongenital AbnormalitiesFolic Acid DeficiencyPregnancy, TwinFetal DeathPreconception CareDiseases in TwinsAmniotic Band SyndromeDietary SupplementsPrenatal CareInfant, NewbornFetal DiseasesAmniotic FluidPrenatal Diagnosis