Human immunodeficiency virus (HIV) is a retrovirus acquired by direct inoculation of infected bodily fluids. This is most often during sexual intimacy, but may also result from contaminated needles or iatrogenic interventions, such as blood transfusion or surgical procedures with contaminated products. The infection is lifelong and if untreated significant morbidity and mortality arise from HIV-associated infections and malignancies; this is termed the acquired immune deficiency syndrome (AIDS). During infection, HIV enters cells presenting CD4 receptors, the most common being the CD4+ T lymphocyte. Within the hosting cell, HIV replication, virion release and eventual cell death occur. The main measurable and prognostic parameters widely used are quantification of peripheral CD4 cells (the CD4 count), and the level of viraemia (HIV viral load). The likelihood of AIDS-defining illness developing increases with progressive CD4+ cell depletion, which occurs steadily over time from infection and more rapidly in individuals with a higher HIV viral load.
The advent of highly active antiretroviral therapy (HAART) in the late 1990s transformed the management of HIV-positive patients, and the infection is now generally treatable with a good prognosis, particularly when detected early. In addition to this, effective HAART together with appropriate obstetric management, infant antiretroviral prophylaxis and avoidance of breastfeeding has reduced rates of mother-to-child transmission (MTCT) of HIV significantly. Universal screening for HIV in UK antenatal clinics from 1999 onwards, followed by appropriate management of mothers and their babies, has resulted in MTCT rates falling from between 20–30%, depending on maternal viral load in the mid-1990s to less than 1% in 2010. Worldwide, of the 34 million people living with HIV, 69% reside in sub-Saharan Africa, with other high-prevalence areas including Asia, the Caribbean and Eastern Europe. Many HIV-positive parturients receiving their antenatal care in the UK have acquired HIV whilst residing in one of the pandemic areas. The estimated UK prevalence in 2009 was 2.2 per 1000 women giving birth; most of these live in urban areas, with London having the highest rates.
Effect of HIV on pregnancy
HIV infection itself does not cause sub-fertility, although HIV-positive women may have decreased fertility due to associated conditions such as concurrent infections or illnesses, opiate use and low weight. HAART itself, particularly protease inhibitors, has been associated with preterm delivery in some studies, but not in others. Of all the available antiretroviral medications only zidovudine is licensed for use in pregnancy. Current information from the Antiretroviral Pregnancy Register and the National Study of HIV in Pregnancy and Childhood indicates that in women taking modern HAART, there is no increased risk of congenital abnormalities. During pregnancy, several risk factors increase the risk of MTCT (Table 24.1).
Antenatal risk factors
Intrapartum risk factors
Effect of pregnancy on HIV
There is no evidence that being pregnant has a deleterious effect on HIV disease or increases the rate of progression. Complications of antiretroviral medications such as for hepatitis can at times be difficult to distinguish from pre-eclampsia and obstetric cholestasis. Pregnant women with HIV are at increased risk of puerperal fever and postpartum complications after caesarean delivery.
Couples contemplating a pregnancy where one or both partners are known to be HIV positive should ideally discuss their plans with their HIV team and, if appropriate, obstetrician. This allows optimal medical management of the HIV-positive partner. For the parturient, this would include a medication review to minimize teratogenicity and fetal harm and commencement of prophylaxis required for opportunistic infections.
Management of HIV in pregnancy
Screening and diagnosis
HIV testing should be offered and encouraged in all pregnancies at booking, and pathways should exist to facilitate urgent referral of all women following a positive result to specialist HIV services able to offer information, support and medical treatment. This includes addressing partner notification and testing existing children, as appropriate.
This should be by a multidisciplinary team (MDT) consisting of a consultant obstetrician, HIV physician, specialist nurses and midwives, a paediatrician and, if needed, psychiatric or perinatal mental health specialists and social services. Women with HIV should undergo the standard routine first trimester screening tests and can have chorionic villus sampling or amniocentesis if clinically indicated (only after HIV test results are known and when HIV viral load is suppressed on HAART) (Table 24.2).
Specific tests for HIV-positive women
Monitoring tests for HIV