We found a matchYour institution may have access to this item. Find your institution then sign in to continue.TitlePrenatal screening for trisomy 18 with free beta human chorionic gonadotrophin as a marker.AuthorsSpencer, K; Mallard, A S; Coombes, E J; Macri, J NPublicationBMJ, 1993, Vol 307, Issue 6917, p1455ISSN0959-8138Publication typearticleDOI10.1136/bmj.307.6917.1455