Background: The Tanzania National AIDS Control Programme has established HIV sentinel surveillance
among antenatal clinic (ANC) attendees as one of the methods for collecting data on HIV prevalence. This
article provides trends on HIV prevalence for 92 sentinel sites that have constantly been part of the
surveillance system since 2001 and have participated in at least three consecutive rounds.
Method: The surveillance population included all pregnant women aged 15–49 years who were attending a
selected sentinel ANC site for the first time for any pregnancy between 2001 and 2011. Serial testing for HIV
infection was done anonymously by detecting for the presence of IgG antibodies to HIV on dried blood
spot (DBS) specimens. HIV trends were calculated taking into account random effects from sites on the
following variables: region, sites and socio-demographic characteristics defined as age, marital status,
parity, education level and duration of stay at present residence.