RT Journal Article SR Electronic T1 Third trimester screening or safer sex to prevent mother to child transmission of HIV JF Sexually Transmitted Infections JO Sex Transm Infect FD BMJ Publishing Group Ltd SP 226 OP 227 DO 10.1136/sti.77.3.226-a VO 77 IS 3 A1 P K C Goon A1 R P F Watkins A1 E G H Lyall A1 J Parry A1 G P Taylor YR 2001 UL http://sti.bmj.com/content/77/3/226.2.abstract AB