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The Contribution of Maternal HIV Seroconversion During Late Pregnancy and Breastfeeding to Mother-to-Child Transmission of HIV

Johnson, Leigh F. PhD*; Stinson, Kathryn MPH*; Newell, Marie-Louise MB, PhD†,‡; Bland, Ruth M. MD†,§; Moultrie, Harry MD, MSc‖,¶; Davies, Mary-Ann MD*; Rehle, Thomas M. MD, PhD*,#; Dorrington, Rob E. MPhil**; Sherman, Gayle G. MD, PhD††,‡‡

JAIDS Journal of Acquired Immune Deficiency Syndromes: April 1st, 2012 - Volume 59 - Issue 4 - p 417–425
doi: 10.1097/QAI.0b013e3182432f27
Epidemiology and Prevention

Background: The prevention of mother-to-child transmission (PMTCT) of HIV has been focused mainly on women who are HIV positive at their first antenatal visit, but there is uncertainty regarding the contribution to overall transmission from mothers who seroconvert after their first antenatal visit and before weaning.

Method: A mathematical model was developed to simulate changes in mother-to-child transmission of HIV over time, in South Africa. The model allows for changes in infant feeding practices as infants age, temporal changes in the provision of antiretroviral prophylaxis and counseling on infant feeding, as well as temporal changes in maternal HIV prevalence and incidence.

Results: The proportion of mother-to-child transmission (MTCT) from mothers who seroconverted after their first antenatal visit was 26% [95% confidence interval (CI): 22% to 30%] in 2008, or 15,000 of 57,000 infections. It is estimated that by 2014, total MTCT will reduce to 39,000 per annum, and transmission from mothers seroconverting after their first antenatal visit will reduce to 13,000 per annum, accounting for 34% (95% CI: 29% to 39%) of MTCT. If maternal HIV incidence during late pregnancy and breastfeeding were reduced by 50% after 2010, and HIV screening were repeated in late pregnancy and at 6-week immunization visits after 2010, the average annual number of MTCT cases over the 2010–2015 period would reduce by 28% (95% CI: 25% to 31%), from 39,000 to 28,000 per annum.

Conclusion: Maternal seroconversion during late pregnancy and breastfeeding contributes significantly to the pediatric HIV burden and needs greater attention in the planning of prevention of MTCT programs.

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*Centre for Infectious Disease Epidemiology and Research, School of Public Health and Family Medicine, University of Cape Town, Cape Town, South Africa

Africa Centre for Health and Population Studies, University of KwaZulu-Natal, Durban, South Africa

Centre for Paediatric Epidemiology and Biostatistics, Institute of Child Health, University College, London, United Kingdom

§Division of Developmental Medicine, University of Glasgow, Glasgow, United Kingdom

Harriet Shezi Children's Clinic, Chris Hani Baragwanath Hospital, Johannesburg, South Africa

Wits Reproductive Health and HIV Institute, Faculty of Health Sciences, University of Witwatersrand

#Human Sciences Research Council, Cape Town, South Africa

**Centre for Actuarial Research, University of Cape Town, Cape Town, South Africa

††Department of Molecular Medicine and Haemotology, Faculty of Health Sciences, University of Witwatersrand, Johannesburg, South Africa

‡‡National Health Laboratory Service, Johannesburg, South Africa.

Correspondence to: Leigh Johnson, PhD, AIA, Faculty of Health Sciences, Centre for Infectious Disease Epidemiology and Research, University of Cape Town, Anzio Road, Observatory 7925, Cape Town, South Africa (e-mail:

Presented at the 5th South African AIDS Conference, Durban, South Africa, June 7–10, 2011.

Supported in part by the South African Medical Research Council and the William and Flora Hewlett Foundation.

The authors have no conflicts of interest to disclose.

Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal's Web site (

Received July 29, 2011

Accepted November 18, 2011

© 2012 Lippincott Williams & Wilkins, Inc.