CLINICAL EVIDENCE CONCISE: A PULICATION OF BMJ PUBLISHING GROUP

HIV: Mother-to-Child Transmission



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What are the effects of measures to reduce mother-to-child transmission of human immunodeficiency virus (HIV)?

BENEFICIAL

Antiretroviral Drugs

One systematic review has found that zidovudine versus placebo significantly reduces the incidence of HIV in infants. One randomized controlled trial (RCT) has found that the longer versus shorter courses of zidovudine (long–long versus short–short courses) given to mother and infant significantly reduces the incidence of HIV in infants. One RCT has found that nevirapine versus zidovudine given to the mother and to her newborn significantly reduces the risk of HIV transmission. One RCT found no additional advantage in giving nevirapine to the mother and infant when transmission rates are already reduced by mothers receiving standard antiretroviral treatment. One RCT has found that zidovudine plus lamivudine versus placebo given in the antenatal and intrapartum period, or in the intrapartum and postpartum period, significantly reduces the risk of transmission of HIV.

LIKELY TO BE BENEFICIAL

Elective Caesarean Delivery

One RCT found limited evidence that elective caesarean delivery versus vaginal delivery in women with HIV reduced the incidence of HIV in infants at 18 months.

TRADE OFF BETWEEN BENEFITS AND HARMS

Avoiding Breastfeeding

One RCT in women with HIV who had access to clean water and health education has found that formula feeding versus breastfeeding significantly reduces the incidence of HIV in infants after 24 months without increasing infant mortality.

UNKNOWN EFFECTIVENESS

Immunotherapy

One RCT found no significant difference in the incidence of HIV in infants of mothers taking hyperimmune globulin versus immunoglobulin without HIV antibody in addition to a standard zidovudine regimen, but it may have been too small to exclude a clinically important difference.

Vaginal Microbicides

We found insufficient evidence about the effects of vaginal microbicides on the transmission of HIV to infants.

LIKELY TO BE INEFFECTIVE OR HARMFUL

Vitamin Supplements

RCTs found no significant difference in the incidence of HIV at birth, six weeks, or three months in the infants of pregnant women given vitamin A or multivitamins versus placebo.

Definition

Mother-to-child transmission of HIV-1 infection can occur during pregnancy, in the intrapartum period, or postnatally through breastfeeding.1 By contrast, HIV-2 is rarely transmitted from mother to child.2 Infected children usually have no symptoms and signs of HIV at birth, but develop them over subsequent months or years.3

Incidence/Prevalence

A review of 13 cohorts found that the risk of mother-to-child transmission of HIV without antiviral treatment is on average about 15 to 20 percent in Europe, 15 to 30 percent in the United States, and 25 to 35 percent in Africa.4 The risk of transmission is estimated to be between 15 and 30 percent during pregnancy, with an additional risk of about 10 to 20 percent postpartum through breastfeeding.5 It has been estimated that 800,000 children younger than 15 years were newly infected with HIV during 2001, bringing the total number of children with HIV/acquired immunodeficiency syndrome (AIDS) to 3 million worldwide.6 Most of these children were infected from their mother, and 90 percent live in sub-Saharan Africa.

Etiology/Risk Factors

Transmission of HIV to children is more likely if the mother has a high viral load.1,7,8 Women with detectable viremia (by p24 antigen or culture) have double the risk of transmitting HIV-1 to their infants than those who do not.1 Breastfeeding also has been shown in prospective studies to be a risk factor.9,10 Other risk factors include sexually transmitted diseases, chorioamnionitis, prolonged rupture of membranes, and vaginal delivery.1115

Prognosis

About 25 percent of infants infected with HIV progress rapidly to AIDS or death in the first year. Some survive beyond 12 years of age.3 One European study found a mortality rate of 15 percent in the first year of life and a mortality rate of 28 percent by five years of age.16 A recent report estimated the mortality rates attributable to HIV/AIDS in children younger than five years in sub-Saharan Africa after correcting for competing causes of mortality.17 HIV accounted for 2 percent of deaths in 1990 rising significantly to almost 8 percent in 1999. Five countries (Botswana, Namibia, Swaziland, Zambia, and Zimbabwe) had rates of HIV-attributable mortality in excess of 30 per 1,000 in children younger than five years.

search date: September 2002

editor's note: Treatment with hyperimmune globulin is in the experimental stage and is not available commercially. Adapted with permission from Volmink J. HIV: mother to child transmission. Clin Evid Concise 2003;10:154–5.

 

REFERENCES

1. John GC, Kreiss J. Mother-to-child transmission of human immunodeficiency virus type 1. Epidemiol Rev. 1996;18:149–57.

2. Adjorlolo-Johnson G, De Cock KM, Ekpini E, et al. Prospective comparison of mother-to-child transmission of HIV-1 and HIV-2 in Abidjan, Ivory Coast. JAMA. 1994;272:462–6.

3. Peckham C, Gibb D. Mother-to-child transmission of the human immunodeficiency virus. N Engl J Med. 1995;333:298–302.

4. The Working Group on MTCT of HIV. Rates of mother-to-child transmission of HIV-1 in Africa, America and Europe: results of 13 perinatal studies. J Acquir Immune Defic Syndr. 1995;8:506–10.

5. Nduati R, John G, Mbori-Ngacha D, et al. Effect of breast-feeding and formula feeding on transmission of HIV-1: a randomized clinical trial. JAMA. 2000; 283:1167–74.

6. Report of the global HIV/AIDS epidemic UNAIDS, Geneva 2002.

7. Mofenson LM. Epidemiology and determinants of vertical HIV transmission. Semin Pediatr Infect Dis. 1994;5:252–6.

8. Khouri YF, McIntosh K, Cavacini L, et al. Vertical transmission of HIV-1: correlation with maternal viral load and plasma levels of CD4 binding site anti-gp 120 antibodies. J Clin Invest. 1995;95:732–7.

9. Dunn DT, Newell ML, Ades AE, et al. Risk of human immunodeficiency virus type-1 transmission through breastfeeding. Lancet. 1992;240:585–8.

10. Miotti PG, Taha ET, Newton I, et al. HIV transmission through breastfeeding: a study in Malawi. JAMA. 1999;282:744–9.

11. UNAIDS (Joint United Nations Programme on HIV/AIDS). Report of the global HIV/AIDS epidemic. June 2000. Geneva: UNAIDS; 2000. UNAIDS/00.13E.

12. Nair P, Alger L, Hines S, et al. Maternal and neonatal characteristics associated with HIV infection in infants of seropositive women. J Acquir Immune Defic Syndr. 1993;6:298–302.

13. Minkoff H, Burns DN, Landesman S, et al. The relationship of the duration of ruptured membranes to vertical transmission of human immunodeficiency virus. Am J Obstet Gynecol. 1995;173:585–9.

14. European Collaborative Study. Risk factors for mother-to-child transmission of HIV-1. Lancet. 1992;339:1007–12.

15. Mofenson LM. A critical review of studies evaluating the relationship of mode of delivery to perinatal transmission of human immunodeficiency virus. Pediatr Infect Dis J. 1995;14:169–76.

16. The European Collaborative Study. Natural history of vertically acquired human immunodeficiency virus-1 infection. Pediatrics. 1994;94:815–9.

17. Walker N, Schwartlander B, Bryce J. Meeting international goals in child survival and HIV/AIDS. Lancet 2002. Accessed online January 6, 2004, at: http://image.thelancet.com/extras/01art9188web.pdf.

This is one in a series of chapters excerpted from Clinical Evidence Concise, published by the BMJ Publishing Group, Tavistock Square, London, United Kingdom. Clinical Evidence Concise is published in print twice a year and is updated monthly online. Each topic is revised every eight months, and users should view the most up-to-date version at http://www.clinicalevidence.com. If you are interested in contributing to Clinical Evidence, please contact Claire Folkes (cfolkes@bmj-group.com). This series is part of the AFP's CME. See “Clinical Quiz” on page 1039.


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