HIV screening in pregnancy
HIV screening in pregnancy |
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Key Words: pregnancy; screening; HIV; breastfeeding; zidovudine
Mother-to-child transmission (vertical transmission) of HIV can occur before or during delivery, or afterwards through breastfeeding. About three hundred infants are born to HIV infected women each year in the United Kingdom. The National Health Service hopes to reduce the numbers of babies with HIV acquired by vertical transmission by 80% by 2002 To achieve this, all pregnant women, regardless of the absence or presence of risk factors are to be offered and recommended an HIV test as an integral part of their antenatal care. An initial uptake of at least 50% is envisaged. However, the mere mention of HIV to any person evokes some resentment and anxiety because of the stigma associated with HIV Infection. This paper sets out the rationale behind recommending universal voluntary HIV screening in pregnancy.
Scope of the problem
The prevalence of HIV infection among pregnant women in the UK (excluding London that has a higher rate of 1:520) was 1 in 5700 in 1996. About three hundred infants are born to HIV infected women each year in the UK and about 10% of previously undetected maternal infections are diagnosed in pregnancy. [1].
The case for HIV screening
For pregnant women, knowing the HIV status is now significantly more useful than in the 1980s and early 1990s. HIV-positive women can benefit from new treatments and such treatment can significantly reduce the risk of HIV transmission from mother to child.
Propelling the need for HIV screening in pregnancy are the occurrence of major scientific advances in the prevention of perinatal transmission of HIV, testing for HIV and the treatment of HIV-positive women. There is clear evidence that transmission of HIV from an infected mother to her child can be greatly reduced by interventions such as anti-retroviral treatment in pregnancy and in the perinatal period, and by the avoidance of breastfeeding. There is also increasing benefits for the woman herself in knowing that she has HIV infection.
Results from a randomised clinical trial (ACTG 076) conducted by the US National Institute of Health show that antiretroviral medication provided to pregnant women during pregnancy, labour and delivery and to the new born during the first six weeks of life can dramatically reduce the risk of vertical transmission of HIV. Other studies have confirmed a reduction in transmission from 25% to 8% or even less [2].
About 91% of children with AIDS are born to mothers infected with or at risk from HIV. One third of these mothers do not report a risk for HIV [3]. HIV infected women will only be in a position to make informed decisions about all measures that are known to protect their babies from HIV infection only if they are aware of their infection status. This buttresses the need to offer all women information about HIV during pregnancy and provide opportunities for HIV testing and counselling. Women are routinely offered the opportunity to undergo HIV testing during pregnancy and counselling about the advantages and disadvantages of HIV testing. It is voluntary and it is of utmost importance that adequate counselling is undertaken. As with other antenatal screening tests, HIV testing should be done with the patient's knowledge and verbal consent. HIV carries with it a stigma and it is important that HIV testing be carried out in such a way as to respect and protect the individual. Practitioners who offer the test to women should be knowledgeable and well equipped to counsel women.
The Test
Screening involves a blood test that can be taken along with other routine antenatal blood tests at booking. To ensure that the numbers of false positive results are minimised, the practice in Northumbria Healthcare NHS Trust is to double check positive test results. Systems have been put in place to ensure that an HIV positive woman receives the emotional support and counselling required and is referred to the appropriate specialist for further management.
HIV-positive women, anti-retroviral therapy and birth defects
Women who test positive should have a choice as to how to proceed with the pregnancy. This will include the decision to continue the pregnancy without taking treatment aimed at reducing the risk of transmission to the baby, she could opt for treatment or decide to abort. Pregnant women being treated with Zidovudine should be offered a caesarean section before the onset of labour and rupture of membranes. This reduces the risk of HIV transmission to the newborn to only 2%. However, caesarean section is associated with higher maternal complications than vaginal delivery. As the risks to the mother are greater, her needs must be balanced with those of the newborn.
The overall risk of birth defects in children born to Zidovudine (ZDV)-treated mothers is 3.7% across all trimesters, consistent with the expected risk of 3-4% of the general population. No onsistent pattern of defects has been reported in both prospective and retrospective studies [4]. .
Infants of HIV-positive women
Mother-to-Child transmission of HIV can occur through breastfeeding. HIV positive women should be provided full information about the relative risks and benefits to their babies of breastfeeding. Postnatal anti-retroviral therapy should be administered to infants of mothers who elect for this treatment.
HIV Screening and Insurance premiums
Acceptance of HIV screening will not affect insurance premiums or result in Insurance companies declining to insure women who have been screened.
Conclusion
The purpose of HIV testing is not to label a woman as infected, but to provide her and her child with the appropriate healthcare. Screening for syphilis in pregnancy resulted in the decline of syphilis infection. Identification of HIV positive women in pregnancy, administration of anti-retroviral drugs and the avoidance of breastfeeding are measures available to combat vertical transmission of HIV.
The potential consequences of undiagnosed HIV in pregnancy can be tragic. The adoption of universal and voluntary HIV testing as a routine component of antenatal care would reduce the vertical transmission of HIV and should be encouraged. Measures to prevent transmission of HIV from mother to child can only be offered if HIV infection is diagnosed in pregnancy.
References
Voluntary confidential reporting by Obstetricians (RCOG), Paediatricians (BPSU/RCPH) and Laboratories (CDSC/PHLS) in: Reducing Mother to Child Transmission of HIV Infection in the United Kingdom, Executive Summary and Recommendations, April 1998, Royal College of Paediatricians and Child Health, London.
Rogers, M. A., Mofenson, L. M. & Moseley, R. R. (1995) Reducing the risk of Perinatal HIV Transmission through Zidovudine Therapy: Treatment Recommendations and Implications. Journal of the American Medical Women's Association, 50(3&4): 78- 82.
American College of Obstetricians and Gynaecologists News Release, May2000. http://www.acog.org/from_home/publications/press_releases/nr05-23-002.htm
CDC (1988): Congenital malformations surveillance report, January 1982-1985, Atlanta, US Department of Health & Human Services, Public Health Service, CDC.
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