Our analysis is subject to limitations resulting from pooling data
from studies with heterogeneous research methodologies. Incident
HIV infections reported in the studies were estimated using tests
that varied in sensitivity and with different intervals for follow-up
testing. Variability in test performance has previously been noted
to result in overestimation of incidence when lower sensitivity tests
are used initially and higher sensitivity tests for subsequent tests
[49]. Timing of seroconversion is also related to timing of testing;
women seeking antenatal care and testing earlier in their
pregnancy have more person-time and opportunity to be detected
as an incident rather than chronic infection. Conversely,
seroconversions early in pregnancy are not captured as incident
infections if antenatal care is sought later. Another limitation of
this analysis is that cumulative incidence based on repeat testing
was estimated from cohorts with differing duration of follow-up
and cross-sectional testing using sensitive assays. While the
performance of assays for detecting recent infections has been
shown to vary across HIV clades and subpopulations, a recent