Human immunodeficiency virus

Testing for HIV in pregnancy enables measures to be taken to reduce the risk of mother-to-child transmission and for the woman to be offered treatment and psychosocial support.

33.1 Background

Human immunodeficiency virus (HIV) is a blood-borne infection that is initially asymptomatic but involves gradual compromise of immune function, eventually leading to acquired immunodeficiency syndrome (AIDS). The time between HIV infection and development of AIDS ranges from a few months to 17 years in untreated patients PHLS 1998. Undiagnosed HIV infection during pregnancy has serious implications for the health of both the woman and her child. Early HIV diagnosis can reduce the risk of mother-to-child transmission and the rate of disease progression in the mother NICE 2008.

33.1.1 HIV in Australia

• Rates of diagnosis of HIV: The number of notifications of newly diagnosed HIV among women in Australia has remained stable for the past 10 years and was 0.7 per 100,000 women in 2016 (The Kirby Institute 2017a). In 2016, notification rates were more than three times higher among Aboriginal and Torres Strait Islander women than among Australian-born non-Indigenous women (1.1 vs 0.3 per 100,000) (The Kirby Institute 2017b).
• Geographical distribution: Recent trends in the population rate of newly diagnosed HIV have differed across jurisdictions. Over the past 10 years (2007–2016) rates per 100,000 fluctuated in Victoria (range 4.4 to 5.3; 2016 rate 5.0), Queensland (range 3.9 to 5.3; 2016 rate 4.1), Western Australia (range 3.0 to 4.3; 2016 rate 3.6), Tasmania (1.0 to 4.2), the Northern Territory (2.6 to 8.1) and the Australian Capital Territory (range 1.8 to 4.2; 2016 rate 3.0) and declined in New South Wales (from 5.8 to 4.2) (The Kirby Institute 2017a).
• Country of origin: In overseas born populations, HIV notification rates per 100,000 in 2016 were 17.3 for people born in the Americas (North and South America), 17.1 for people born in South-East Asia, 10.9 for people born in sub-Saharan Africa and 7.3 for people born in North-East Asia and (The Kirby Institute 2017a).
• Risk factors: Transmission of HIV in Australia continues to occur primarily through sexual contact between men. In 2015, 20% of new HIV diagnoses were attributed to heterosexual sex and 3% to injecting drug use (The Kirby Institute 2016). Of new diagnoses attributed to heterosexual sex, 36% were in people from high-prevalence countries or with partners from high prevalence countries.
• Perinatal exposure: Among 223 women with HIV who gave birth in the 5-year period 2012–2016, the transmission rate to newborns was 2%, compared to 39% in the period 1985–1991 and 28% in 1992–1996 (The Kirby Institute 2017a). In the past 10 years, the transmission rate has dropped from 9% in 2007 to 0% in 2016.

33.1.2 Risks associated with HIV infection in pregnancy

Globally, most children with HIV acquire infection through mother-to-child transmission during pregnancy, during birth or through breastfeeding (Volmink et al 2007). Maternal viral load is a strong independent determinant of transmission risk Khouri et al 1995, Mofenson 1995, John & Kreiss 1996, Warszawski et al 2008.

33.2 Testing for HIV infection in pregnancy

Universal testing for HIV in pregnancy is recommended in the United Kingdom de Ruiter et al 2008, NICE 2008, RCOG 2010, the United States (Branson et al 2006) and Canada SOGC 2006, CPS 2008. These policies are based on the availability of accurate diagnostic tests and effectiveness of antiretroviral treatment in preventing mother-to-child transmission. They also reflect the fact that testing based on risk factors would miss a substantial proportion of women with HIV (Chou et al 2005).

33.2.1 Diagnostic accuracy of tests

Tests for HIV diagnosis in pregnant women include:

• standard tests: the enzyme immunoassay (EIA) and Western blot protocol is highly (>99%) sensitive and specific Samson & King 1998, Bulterys et al 2004, Chou et al 2005, Chappel et al 2009
• rapid HIV tests, which have similar accuracy Bulterys et al 2004, Chou et al 2005 and provide results within hours without requiring a return visit (Tepper et al 2009), with blood-based tests having greater sensitivity than tests using oral fluids (Pai et al 2007).

The sensitivities and specificities of various commercial HIV assays can be found at the Therapeutic Goods Administration website.

33.2.2 Interventions to prevent mother-to-child transmission

Cochrane reviews into the effectiveness of interventions in preventing mother-to-child transmission have found that:

• short courses of certain antiretroviral medicines are effective and are not associated with any safety concerns in the short term (Volmink et al 2007)
• caesarean section before labour and before ruptured membranes is effective among women with HIV not taking antiretrovirals or taking only zidovudine (Read & Newell 2005)
• vitamin A supplementation is not effective in preventing transmission (Wiysonge et al 2011)
• there is no evidence of an effect of vaginal disinfection (Wiysonge et al 2005)
• complete avoidance of breastfeeding is effective in preventing mother-to-child transmission of HIV (Horvath et al 2009)
• if breastfeeding is initiated, the combination of exclusive breastfeeding during the first few months of life and extended antiretroviral prophylaxis to the infant is effective (Horvath et al 2009).

Prospective cohort studies and meta-analyses have not found a significant association between antiretroviral treatments and intrauterine growth restriction (n=8,192) Briand et al 2009, congenital anomalies (n=8,576) (Townsend et al 2009), or preterm birth (n=20,426) (Kourtis et al 2007).

Recommended interventions appear to be acceptable to pregnant women and are associated with mother-to-child transmission rates of 1% to 2% (Chou et al 2005). In Australia between 1982 and 2005, uptake of interventions to reduce mother-to-child transmission of HIV was high (Giles et al 2008).

33.3 Pre-test and post-test discussions

Pre- and post-test discussions are an integral part of HIV testing.

33.3.1 Considerations before testing

Providing information and support associated with testing aims to minimise the personal and social impact of HIV infection. The Australian Department of Health and Ageing HIV testing guidelines recommend that DoH 2006:

• antenatal testing only be performed with the informed consent of the woman
• all women contemplating pregnancy or seeking antenatal care be made aware of the benefits of diagnosis of HIV infection and management, and prevention strategies available for both the mother and the baby
• women receive materials (in written and other formats) outlining the tests that will be offered antenatally and explaining the testing procedure
• women with limited literacy or for whom English is a second language receive appropriate educational resources (eg using media such as video, audio, multimedia or in languages other than English)
• women with a first language other than English be offered access to accredited interpreting services.

Women most at risk of HIV may decline testing Boxhall 2004, Plitt 2007 or may not access testing and available interventions Ferguson et al 2008, Struik 2008. Women who decline testing should be given opportunities to discuss any concerns.

33.3.2 Considerations after testing

Women who accept testing may experience anxiety while waiting for the initial test result or while waiting for results of repeat testing.

Unexpected detection of HIV can result in distress, which is exacerbated in the context of pregnancy. Health professionals delivering the test result should use their best judgement when deciding the most appropriate way to deliver the test result DoHA 2006.

33.4 Testing in rural and remote areas

Rapid tests improve the availability of HIV testing in situations where there is limited access to pathology services and returning for results may be difficult DoHA 2006. However, the use of these tests should be limited to situations where DoHA 2006:

• testing is conducted in, or backed up by, a clinical setting
• testing is conducted under the auspice of a National Association of Testing Authorities/Royal College of Pathologists of Australia medical testing accredited laboratory
• reliable Therapeutic Goods Administration approved rapid tests are available
• high quality information on the tests and their use is available and provided
• the health professional performing the test is suitably trained in conducting and interpreting the test and has the skills to provide pre- and post-test information/discussion (if conducted outside an accredited laboratory)
• quality assurance programs are available to ensure ongoing competency of healthcare professionals performing the tests.

33.5 Practice summary: HIV

When

Early in antenatal care.

Who

• Midwife
• GP
• obstetrician
• Aboriginal and Torres Strait Islander health worker
• multicultural health worker.

What

• Discuss HIV testing
  Explain that it is important to find out whether a woman has HIV because of the risk of transmission to the baby. Testing also gives the woman the opportunity to receive appropriate treatments.
• Document and follow-up
  Note the results of HIV testing in the woman’s record and have a follow-up system in place so women who have HIV have access to counselling to discuss the test results and available interventions to prevent transmission during pregnancy.
• Take a holistic approach
  If a woman is found to have HIV, specialist advice on management is required. Other considerations include psychosocial support, contact tracing, partner testing, testing for other sexually transmitted infections and continuing follow-up.

33.6 Resources

• ASHA (2016) Australian STI Management Guidelines for Use in Primary Care. Australasian Sexual Health Alliance. Accessed: 10 August 2018.
• DoHA (2011) National HIV Testing Policy 2011. Canberra: Australian Government Department of Health.
• RCOG (2010) Green Top Guideline no 39 Management of HIV in Pregnancy. London: Royal College of Obstetricians and Gynaecologists.