Serological screening for sexually transmitted infections in pregnancy: is there any value in re-screening for HIV and syphilis at the time of delivery?

OBJECTIVE The aim of this study was to assess the prevalence of syphilis, human immunodeficiency virus (HIV), and hepatitis B virus (HBV) infections in women at the time of delivery, and to determine the seroconversion rates for syphilis and HIV infections from initial booking visit to delivery. SETTING The labour ward of a typical tertiary hospital in a developing country and serving an indigent African population. METHOD Four hundred and eighteen women presenting in labour were randomly selected and informed consent obtained for serological testing for syphilis and HBV infections in umbilical cord blood samples. The specimens were then given a study number, the gestational ages recorded and anonymously tested for HIV infection. RESULTS Of the 191 women who had antenatal care, 13 (6.8%) were HIV antibody positive at the initial "booking" visit. An additional 4 were found to be HIV antibody positive at the time of delivery resulting in a seroconversion rate of 2.2%. The seroconversion rate for syphilis at the time of delivery was 2.7%. Hepatitis B surface antigens were detected in only 2 women, one of whom was antigen positive. CONCLUSION The high seroconversion rates for both syphilis and HIV infection in pregnancy justifies re-screening for these conditions in endemic areas such as ours.