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Vertical transmission rates for HIV in the British Isles: estimates based on surveillance data

BMJ 1999; 319 doi: https://doi.org/10.1136/bmj.319.7219.1227 (Published 06 November 1999) Cite this as: BMJ 1999;319:1227
  1. Trinh Duong, statisticiana,
  2. A E Ades, reader (a.ades{at}ich.ucl.ac.uk)a,
  3. Diana M Gibb, senior lecturer in epidemiologyb,
  4. Pat A Tookey, senior research fellowa,
  5. Janet Masters, research assistanta
  1. a Department of Epidemiology and Public Health, Institute of Child Health, London WC1N 1EH
  2. b Clinical Trials Unit, Medical Research Council, Mortimer Market Centre, London WC1E 6AU
  1. Correspondence to: A E Ades
  • Accepted 19 July 1999

Abstract

Objective: To estimate and interpret time trends in vertical transmission rates for HIV using data from national obstetric and paediatric surveillance registers.

Design: Prospective study of HIV infected women reported through obstetric surveillance. HIV infection status of the child and onset of AIDS were reported through paediatric surveillance. Rates of vertical transmission and progression to AIDS rate were estimated by methods that take account of incomplete follow up of children with indeterminate infection status and delay in AIDS reporting.

Setting: British Isles.

Subjects: Pregnant women infected with HIV whose infection was diagnosed before delivery, and their babies.

Main outcome measures: Mother to child transmission of infection and progression to AIDS in children.

Results: By January 1999, 800 children born to diagnosed HIV infected women who had not breast fed had been reported. Vertical transmission rates rose to 19.6% (95% confidence interval 8.0% to 32.5%) in 1993 before falling to 2.2% (0% to 7.8%) in 1998. Between 1995 and 1998 use of antiretroviral treatment increased significantly each year, reaching 97% of live births in 1998. The rate of elective caesarean section remained constant, at around 40%, up to 1997 but increased to 62% in 1998. Caesarean section and antiretroviral treatment together were estimated to reduce risk of transmission from 31.6% (13.6% to 52.2%) to 4.2% (0.8% to 8.5%). The proportion of infected children developing AIDS in the first 6 months fell from 17.7% (6.8% to 30.8%) before 1994 to 7.2% (0% to 15.7%) after, coinciding with increased use of prophylaxis against Pneumocystis carinii pneumonia.

Conclusions: In the British Isles both HIV related morbidity and vertical transmission are being reduced through increased use of interventions

Key messages

  • Reliable estimates of HIV vertical transmission rates can be derived from surveillance data

  • Infected pregnant women are increasingly taking up elective caesarean section and antiretroviral treatment to reduce the risk of transmitting HIV to their babies

  • Vertical transmission rates have fallen greatly over the past four years and progression to AIDS among infected children may also have slowed

  • These benefits can occur only if infected women are diagnosed before or during pregnancy

Footnotes

  • Funding TD, PAT, and JM were supported by grants from AVERT (Aids Education and Research Trust) and the Department of Health.

  • Competing interests None declared.

  • website extra A longer version of this paper is available on the BMJ's website www.bmj.com

  • Accepted 19 July 1999
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