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Objectives:Rates of pregnancy and HIV infection are high among South African adolescents, yet little is known about rates of mother-to-child transmission of HIV (MTCT) in this group. We report a comparison of the characteristics of adolescent mothers and adult mothers, including HIV prevalence and MTCT rates.Methods:We examined patterns of health service utilization during the antenatal and early postnatal period, HIV prevalence and MTCT amongst adolescent (<20-years-old) and adult (20 to 39-years-old) mothers with infants aged ≤16 weeks attending immunization clinics in six districts of KwaZulu-Natal between May 2008 and April 2009.Findings:Interviews were conducted with 19,093 mothers aged between 12 and 39 years whose infants were aged ≤16 weeks. Most mothers had attended antenatal care four or more times during their last pregnancy (80.3%), and reported having an HIV test (98.2%). A greater proportion of HIV-infected adult mothers, compared to adolescent mothers, reported themselves as HIV-positive (41.2% vs. 15.9%, p<0.0001), reported having a CD4 count taken during their pregnancy (81.0% vs. 66.5%, p<0.0001), and having received the CD4 count result (84.4% vs. 75.7%, p<0.0001). Significantly fewer adolescent mothers received the recommended PMTCT regimen. HIV antibody was detected in 40.4% of 7,800 infants aged 4-8 weeks tested for HIV, indicating HIV exposure. This was higher among infants of adult mothers (47.4%) compared to adolescent mothers (17.9%, p<0.0001). The MTCT rate at 4-8 weeks of age was significantly higher amongst infants of adolescent mothers compared to adult mothers (35/325 [10.8%] vs. 185/2,800 [6.1%], OR 1.7, 95% CI 1.2-2.4).Conclusion:Despite high levels of antenatal clinic attendance among pregnant adolescents in KwaZulu-Natal, the MTCT risk is higher among infants of HIV-infected adolescent mothers compared to adult mothers. Access to adolescent-friendly family planning and PMTCT services should be prioritised for this vulnerable group. © 2013 Horwood et al.
Written informed consent was obtained in the local language from all adult participants, and from parents or legal guardians of participating infants. The University of KwaZulu-Natal Biomedical Ethics Review Committee granted ethical approval for the study. Participants were part of the KZN PMTCT Impact Study (2008–2009), a large cross-sectional survey designed to assess the impact of the PMTCT programme in six of the 11 districts in KZN. Full details on the sampling, methods and main findings have been previously reported [13]. Briefly, data were collected from all mothers with children aged younger than six years attending well-child clinics (Figure 1). Fathers and legal guardians attending immunisation clinics with infants aged four to eight weeks were also interviewed. Three of the participating districts were primarily urban and three primarily rural. All fixed clinics providing immunisations were included in the sample; mobile clinics were excluded. Structured questionnaires were administered in the local language by trained field workers. Data collectors were trained for two weeks and closely supervised throughout the period of data collection. All completed questionnaires were checked for accuracy and completeness and field workers received feedback if any errors were made. Mothers were asked about their history of HIV testing and uptake of PMTCT services in their most recent pregnancy, including receiving antiretroviral drugs (ARVs) for PMTCT prophylaxis or as lifelong antiretroviral therapy (ART). Written informed consent was requested from mothers and legal guardians of infants aged between four and eight weeks (i.e. 28–62 days) for anonymous HIV testing of the infants, regardless of the reported HIV status of the mother or her participation in the PMTCT programme. Dried blood spot (DBS) samples were obtained from infants by heel prick using a spring-loaded lancing device (Accu-chek Softclix, Roche diagnostics, Burgess Hill, United Kingdom), and whole blood was collected onto filter paper and dried. DBS samples were first tested for HIV antibody (Biomerieux Vironostika HIV Uni-Form II plus O, Boxtel, The Netherlands), thus reflecting maternal HIV infection. If HIV antibodies were detected, the same DBS sample was tested for HIV DNA by PCR (HIV-1 DNA AMPLICOR VERSION 1.5 Roche Diagnostics, Pleasanton, California, USA). Mothers were also offered linked HIV testing of their infants with return of results. The analyses were restricted to mothers presenting with infants aged ≤16 weeks to reduce recall bias and to ensure that results reflect recent PMTCT coverage. For the purposes of this analysis we defined ‘adolescents’ as those aged 12–19 years, and ‘adults’ as those aged 20–39 years. Simple frequency rates were used to assess PMTCT uptake in the last pregnancy. Maternal HIV infection status and HIV transmission rates were estimated based on results of HIV testing of infants four to eight weeks of age. Bivariate analyses were conducted to examine the association between maternal HIV status and socio-demographic and other risk factors. Amongst women whose infant was HIV antibody positive, bivariate analyses were conducted to examine the association between mother’s age at delivery (12–19 years versus 20–39 years) and maternal ARV prophylaxis in pregnancy and MTCT. Multivariable logistic regression analyses were conducted using a full model with all potential covariates. Factors were kept in the model based on a priori hypotheses. Odds ratios (OR) and 95% confidence intervals (CI) for associations between maternal age, HIV infection status and HIV transmission to infants were calculated by generalized estimation equations (GEE) using Proc Genmod (SAS Institute) to account for potential correlation of outcomes measured in the same clinic [14]. All statistical analyses were performed using SAS, version 9.2 (SAS Institute, Cary, NC, USA).
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