There is a high
risk of HIV seroconversion during pregnancy for women in South Africa,
investigators report in the online journal PLOS
One. The study involved approximately 10,000 mother and infant pairs and
found that 3% of mothers became infected with HIV during pregnancy, accounting
for over a quarter of all cases of mother-to-child transmission (MTCT) of HIV.
believe their findings have important implications for prevention of mother-to-child
transmission programmes in South Africa, and urge that women should have repeat
screens for HIV infection after week 32 of pregnancy, during labour and again
six weeks after giving birth. Women with HIV-positive partners and those
undergoing screening for tuberculosis (TB) should also, the investigators recommend,
be prioritised for HIV testing.
African guidelines for the prevention of mother-to-child transmission of HIV recommend that women
should be screened for HIV infection when first presenting to antenatal care,
with retesting at week 32 of pregnancy and during labour. The aim is early
identification of infections to allow interventions that can reduce the risk of mother-to-child transmission to below 1%.
has shown that many women continue to have an ongoing risk of infection with
HIV during pregnancy. HIV viral load is very high during seroconversion,
meaning that women infected with HIV during pregnancy could have a significant
risk of transmitting HIV to their baby.
A team of investigators
therefore designed a population-based study to estimate the rate of HIV
seroconversion during pregnancy after an antenatal HIV-negative test result,
and the contribution of infection with HIV during pregnancy to early mother-to-child transmission risk.
The study involved
9800 mother and infant pairs. The infants were aged between four and eight
weeks. Infant dried blood spots were tested for HIV antibodies and DNA. The
mothers’ medical records were reviewed, and they were also interviewed about
possible HIV risk during pregnancy. Recruitment took place at 578 health
facilities between August 2011 and March 2012.
of mothers had prevalent HIV infection and just over 3% seroconverted during
The median time of
seroconversion was week 33 of gestation, but in 28% of cases, seroconversion
occurred after week 36.
seroconversion during pregnancy was associated with a significant risk of early mother-to-child transmission. Approximately 11% of infants whose mothers seroconverted during pregnancy
were infected with HIV; the rate of early mother-to-child transmission for mothers with
prevalent HIV infection was 2%.
mothers seroconverting during pregnancy represented 2% of all mothers and 7% of
all mothers with HIV. However, they accounted for 26% of all cases of mother-to-child transmission
of the women who seroconverted reported knowing the HIV status of their
partner, with 2% stating their partner was HIV positive. The authors were
concerned about the apparent “very low rates of HIV disclosure among sexually
active couples,” and stress that World Health Organization guidelines recommend offering counselling
and testing to all pregnant women in prevention of mother-to-child transmission settings.
for TB and having a HIV-positive partner were associated with a higher risk of
seroconversion during pregnancy. Moreover, women who seroconverted were less
likely than HIV-negative women to have had a doctor or nurse present when they
finding indicates that pregnant women have a high risk of acquiring HIV in
pregnancy,” write the authors. “We believe provision of a package of both
tuberculosis screening and HIV testing would improve early detection of both
HIV infections, including incident infection, and tuberculosis infection.”
recommend that priorities for prevention
of mother-to-child transmission programmes in South Africa should include:
- Repeat HIV testing at weeks 32
and 36 of gestation, at labour and six weeks postpartum.
- Couples counselling and testing
with early antiretroviral treatment (ART) for HIV-positive partners in serodiscordant
- HIV testing and TB screening in
“successfully implementing these interventions could help in early detection of
incident HIV infection occurring during pregnancy, and early initiation of ART
to reduce MTCT risk during pregnancy and breastfeeding.”