Introduction

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).

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.

Preconception

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

Antenatal management

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).

Table 24.2 Antenatal management of the HIV-positive parturient

First trimester Standard booking tests Specific tests for HIV-positive women Hepatitis B (if HBV infection, quantitative HBV DNA, hepatitis A virus (HAV), HCV and hepatitis delta virus (HDV), liver function tests) Hepatitis C (if HCV infection, quantitative VL and genotype, liver function tests) Serology for syphilis, toxoplasmosis, varicella zoster, measles HIV resistance testing Monitoring tests for HIV Baseline CD4 cell count at booking Frequency of checking CD4 count, plasma viral load and drug levels should be according to recommendations of HIV physician Pregnant women on HAART will require a viral load (VL) 2–4 weeks after commencing HAART, at least once every trimester, at 36 weeks and at delivery Full blood count, renal, bone and liver profile tests before starting HAART treatment and at each antenatal visit Vaccination of HIV-positive women for hepatitis B, pneumococcus and influenza Second trimester Second trimester anomaly scan at 18 + 0 to 20 + 6 weeks’ gestation Offer quadruple test between 15 + 0 to 20 + 0 weeks’ gestation in women that have missed combined screening test Offer HIV screening at 28 weeks’ gestation if previously declined Screen for genital tract infections at 28 weeks’ gestation HIV disease monitoring with plasma viral load and drug toxicities should be performed according to recommendations of HIV physician Third trimester A decision on mode of delivery should be made by 36 weeks’ gestation A delivery care plan individualized to the woman should be issued and made available to all healthcare professionals involved in her care. A copy should be carried by the patient ECV should be offered to women with a VL <50 copies/mL and breech presentation at >36 weeks’ gestation in the absence of obstetric contraindications Women with a plasma VL of <50 HIV RNA copies/mL at 36 weeks’ gestation and in the absence of obstetric contraindications should be offered a planned vaginal delivery Women with a plasma VL of 50–399 HIV RNA copies/mL at 36 weeks’ gestation should be offered a prelabour planned elective caesarean section at 38 weeks’ gestation Delivery by prelabour planned elective caesarean section at 38 weeks’ gestation is recommended for women taking zidovudine monotherapy, irrespective of plasma VL at the time of delivery and for women with VL >400 HIV RNA copies/mL regardless of ART Delivery by prelabour planned elective caesarean section for obstetric indications or maternal request should be delayed until after 39 weeks’ gestation in women with VL <50 HIV RNA copies/mL to reduce the risk of transient tachypnoea of the newborn

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