DOI: 10.1111/j.1744-4667.2011.00076.x
2012;14:17–24
The Obstetrician & Gynaecologist
Review
http://onlinetog.org
HIV in pregnancy: an international perspective Laura Byrne MRCP,a,∗ Ade Fakoya FRCP,b Kate Harding FRCOGc a
Specialty Registrar in Genitourinary & HIV Medicine, Ambrose King Centre, The Royal London Hospital, Turner Street, London E1 1BB, UK Honorary Senior Research Fellow, Primary Care & Population Health, Faculty of Population Health Sciences, University College London, Gower Street, London WC1E 6BT, UK c Consultant Obstetrician, Department of Obstetrics, St Thomas’ Hospital, Westminster Bridge Road, London SE1 7EH, UK ∗ Correspondence: Laura Byrne. Email:
[email protected] b
Key content:
r The HIV epidemic continues to be a major challenge to global
health.
r Mother to child transmission accounts for 90% of HIV infections
in childhood.
r Transmission of HIV from mother to child is largely preventable. r The implementation of interventions to prevent mother to child
transmission of HIV has been successful in the developed world.
r Prevention of mother to child transmission of HIV in the
developing world is limited by resources, lack of infrastructure and stigma.
Objectives:
r To outline the interventions that have been shown to reduce
mother to child transmission of HIV in both the developed and developing worlds. r To discuss the challenges in the prevention of mother to child transmission faced by the international community. Ethical issues:
r Should we take cost into account when writing guidelines for
preventing mother to child transmission of HIV in resource-poor settings? Keywords highly active antiretroviral therapy / HIV testing / infant
feeding / mother to child transmission / short-term antiretroviral therapy Please cite this paper as: Byrne L, Fakoya A, Harding K. HIV in pregnancy: an international perspective. The Obstetrician & Gynaecologist 2012;14:17–24.
Introduction The HIV epidemic continues to be a major challenge for global health. The latest figures published by the World Health Organization (WHO)1 show that there are 34 million people living with HIV and 2.02 million of these are children under the age of 15 who require antiretroviral therapy. In 2010 there were 390 000 new HIV infections in children and over 90% of these were acquired by mother to child transmission.1 The HIV epidemic has also had a negative impact on maternal mortality rates, especially in Eastern and Southern Africa.2 Globally, HIV/AIDS is now the leading cause of mortality among women of reproductive age and in several high-prevalence countries, such as South Africa and Zimbabwe, HIV is the leading cause of maternal mortality.3 The challenges in the prevention of mother to child transmission centre on scaling up services to meet the current recommendations of universal antenatal testing in areas of high HIV prevalence and antiretroviral therapy for all HIVpositive pregnant women. Access to antenatal care is variable in resource-limited countries. While 98% of pregnant women in high-income countries report at least one antenatal visit with a skilled health worker, this figure is at most 68% in the developing world (range 28–100%).4 In resource-limited
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settings only 35% of pregnant women receive an HIV test and 48% of HIV-positive pregnant women receive effective antiretroviral therapy to prevent mother to child transmission, although this is a significant improvement on the 10% in 2004.1, 5 In resource-rich countries, the implementation of multiple evidence-based interventions has reduced mother to child transmission of HIV to very low levels. The mother to child transmission rate in the UK is 1.2% overall and 0.8% in women who have been on antiretroviral therapy for at least the last 2 weeks of their pregnancy.6 To reduce the number of children infected or affected by HIV, the WHO and Joint United Nations Programme on HIV/AIDS (UNAIDS) have proposed a comprehensive approach consisting of four main strategies:5 1 Primary prevention of HIV among women of childbearing age 2 Preventing unintended pregnancies among women living with HIV 3 Preventing HIV transmission from women living with HIV to their infants 4 Providing appropriate treatment, care and support to mothers living with HIV and their children and families.
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HIV in pregnancy: an international perspective
This article focuses on the interventions that are effective in addressing the third strategy:
r r r r
antenatal HIV testing antiretroviral therapy during pregnancy, labour and the postnatal period optimal management of labour and delivery support of infant feeding choice.
We review both the guidance in the UK and guidance from WHO, which is intended primarily for resource-limited countries.
Timing and factors affecting mother to child transmission of HIV Transmission rates in untreated non-breastfeeding populations in resource-rich countries range from 14–32%, compared with 25–48% among breastfeeding populations in resourcepoor settings.7 HIV transmission from mother to child can occur antenatally (in utero), during the intrapartum period and postnatally (through breastfeeding). The absolute risk of these modes of transmission has been estimated at 5–10%, 10–20% and 5–30%, respectively.8 It is important to differentiate between modes of transmission, as these inform prevention strategies. Please see Table 1 for a summary of estimated risks of transmission by population and intervention. All infants born to HIV-positive mothers have serum HIV antibodies because of passive placental transfer, which persist up to 18 months of age; this does not indicate infection with the virus. A positive HIV DNA on polymerase chain reaction testing from the infant before 7 days of age indicates in utero transmission; if positive at 1 month this indicates intrapartum transmission, although the cut-offs are not absolute.9 The risk factors associated with HIV transmission are well documented (see Box 1). There is a strong positive correlation between maternal antenatal viral load and the risk of both in utero and intrapartum transmission;10 interventions to reduce maternal viral load reduce HIV transmission risk. Duration of ruptured membranes has been associated with intrapartum transmission in previous research,9, 11 although new UK data show that this may not be the case for women on effective highly active antiretroviral therapy (HAART) with undetectable viral loads.12
The multidisciplinary approach HIV-positive pregnant women are best managed by a multidisciplinary team. This may include a specialist midwife, HIV (or infectious disease) physician, an obstetrician with an interest in HIV, a paediatrician, an HIV community nurse specialist and a pharmacist. This team is responsible both for women with known HIV and those who are newly diagnosed.
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Box 1. Factors associated with risk of mother to child transmission of HIV
Increased risk High maternal HIV viral load Low maternal CD4 count Low weight for gestational age Chorioamnionitis Concurrent maternal sexually transmitted infection
Decreased risk Low maternal HIV viral load Antiretroviral therapy during pregnancy Elective caesarean section Avoidance of breastfeeding
The team will give the positive HIV result, manage the pregnancy, delivery and care of the infant and support the woman and her family through what is often a traumatic time.
Antenatal HIV testing Early detection of antenatal HIV infection ensures that pregnancy and delivery, as well as infant feeding options, can be managed to minimise the risk of vertical HIV transmission. Antenatal HIV screening also helps to ensure that HIV-negative women can protect themselves against acquiring the virus. One of the successes in the UK has been the normalisation of HIV testing as part of routine investigations undertaken during pregnancy. The British HIV Association (BHIVA) guideline on HIV testing recommends universal opt-out testing in both antenatal and pregnancy termination services;13 the HIV test is done along with routine booking blood tests unless the woman specifically declines it. The guideline states that it should be within the competence of any doctor, midwife, nurse or trained healthcare worker to obtain consent for and conduct an HIV test. Before the adoption of universal opt-out HIV testing in antenatal clinics, only a third of HIV-positive pregnant women were diagnosed by delivery and most of these had already been diagnosed prior to conception.14 The latest Health Protection Agency figures from 2009 show that the uptake of antenatal HIV testing in the UK is around 95%.15 International guidance recommends that HIV testing and counselling is offered to all women attending antenatal, delivery and postnatal services in generalised HIV epidemics.16 Global figures for the uptake of antenatal testing are less encouraging than those in the UK, although they are improving. In 2010 only 35% of women giving birth in low or middle-income countries received an HIV test, up from 15% in 2007. In sub-Saharan Africa, the corresponding percentage increase was from 17% to 42%.1 The rise in provider-initiated, rapid point-of-care tests (which do not require laboratory processing) has been instrumental in increasing the uptake of HIV testing among pregnant women in areas of high HIV prevalence.5 Barriers to HIV testing in these settings are multitudinous and include:
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Byrne et al.
Table 1. Estimated risk of vertical HIV transmission by population and intervention6, 8, 22, 23, 30, 36–45, 50, 51 Estimated risk of vertical vertical transmission (%)∗
Population
Intervention
Resource-poor, breastfeeding Resource-poor, non-breastfeeding Resource-rich, non-breastfeeding Resource-poor, breastfeeding Resource-poor, non-breastfeeding Resource-poor, breastfeeding Resource-rich, non-breastfeeding Resource-rich, non-breastfeeding
None None Elective caesarean section Daily AZT Daily AZT Maternal HAART to 6 months postnatal +/- infant prophylaxis HAART HAART Maternal viral load
