Roger Chou, M.D.; Ariel K. Smits, M.D., M.P.H.; Laurie Hoyt Huffman, M.S.; Rongwei Fu, PhD; and P. Todd Korthuis, M.D., M.P.H.
Address correspondence to Roger Chou, M.D., Oregon Health & Science University, Mail Code BICC, 3181 SW Sam Jackson Park Road, Portland, OR 97239; E-mail, chour@ohsu.edu.
Select for copyright, source, and reprint information. The USPSTF recommendation based on this update is available online.
To update its 1996 recommendations, the U.S. Preventive Services Task Force (USPSTF) commissioned a new systematic review of the risks and benefits of prenatal testing for anti-HIV antibodies in asymptomatic women.
Contents
Background
Methods
Results
Discussion
Acknowledgments
References
Notes
Background
Women are the fastest-growing group of persons with new HIV diagnoses, accounting for 30 percent of new U.S. infections in 2001.1,2 An estimated 6000 to 7000 HIV-positive women give birth each year in the United States,3 and 280 to 370 HIV-infected infants were born in the United States annually between 1999 and 2001.4
In 2000, 40 percent of HIV-infected infants were born to mothers not known to have HIV infection before delivery.5 As of 2003, about 5000 cumulative deaths from perinatally acquired AIDS had occurred in the United States.6
Mother-to-child transmission of HIV infection can occur during pregnancy (antepartum), during labor and delivery (intrapartum), and after delivery (postnatal). In the absence of breastfeeding, antepartum transmission is thought to account for 25 percent to 40 percent of cases of mother-to-child transmission; the remaining cases occur during labor and delivery.7 Pregnancy and labor management techniques that minimize contact between infected maternal blood and the fetus can decrease the risk for transmission.8 Breastfeeding is thought to be the only important mode for postnatal transmission.4,9 and accounts for about 44 percent of infant cases in settings with high breastfeeding rates.10 Higher maternal viral loads and lower CD4 counts are associated with an increased risk for transmission.11-15 In the United States, combination antiretroviral regimens, in conjunction with avoidance of breastfeeding and cesarean section before labor and before rupture of membranes (elective cesarean section) in selected women, are the standard of care to reduce mother-to-child transmission of HIV.16,17
To update its 1996 recommendations, the U.S. Preventive Services Task Force (USPSTF) commissioned a new systematic review of the risks and benefits of prenatal testing for anti-HIV antibodies in asymptomatic women.18
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Methods
The Figure summarizes the analytic framework and key questions for this review. Key question 1 addresses direct evidence on the effects of screening on clinical outcomes. The other key questions address the chain of evidence necessary to estimate the effects of screening on clinical outcomes if direct evidence is insufficient. Appendix A discusses the scope and the methods used for this review in more detail.
Briefly, we identified relevant studies from MEDLINE® (1983 through 30 June 2004) and the Cochrane Clinical Trials Registry (2004, issue 2), reference lists, hand searches of relevant journals, and suggestions from experts (Appendix B). We selected studies that provided evidence on the benefits and harms of screening, risk factor assessment, followup testing, interventions, and the acceptability of prenatal HIV testing. For interventions, we focused on studies of the safety and effectiveness of antiretroviral prophylaxis.17 We also reviewed studies on the safety and effectiveness of elective cesarean section19 and avoidance of breastfeeding. A separate report23 reviews other recommended interventions, such as vaccinations, prophylaxis against opportunistic infections, and routine monitoring and followup.7,20-22
We assessed the internal validity and relevance of included studies using predefined criteria developed by the USPSTF (Appendix C).24 We rated the overall body of evidence for each key question using the system developed by the USPSTF.
We used the results of the evidence review to construct an outcomes table estimating the effects of one-time screening for HIV infection in hypothetical cohorts of pregnant women. We calculated numbers needed to screen (NNS) and treat (NNT) to prevent 1 case of mother-to-child transmission or to cause 1 complication from interventions. The point estimates and 95% CIs for NNS and NNT were based on Monte Carlo simulations.
This research was funded by the Agency for Healthcare Research and Quality (AHRQ) under a contract to support the work of the USPSTF. Agency staff and USPSTF members participated in the initial design of the study and reviewed interim analyses and the final report. Draft reports were distributed to 13 content experts for review. Agency approval was required before this manuscript could be submitted for publication, but the authors are solely responsible for the content and the decision to submit it for publication.
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Results
Does Screening for HIV in Pregnant Women Reduce Mother-to-Child Transmission or Premature Death and Disability?
No studies compare clinical outcomes from screening or not screening pregnant women for HIV. Although the number of infants with perinatally acquired HIV transmission has markedly declined in the United States, this reduction is probably due to a combination of increased prenatal screening and increased effectiveness and uptake of therapies.3,7 No studies estimated the relative impact of these factors.
Can Clinical or Demographic Characteristics Identify Subgroups of Asymptomatic Pregnant Women at Increased Risk for HIV Infection Compared to the General Population of Pregnant Women?
Risk factors for HIV infection appear similar in pregnant and nonpregnant women and include risky sexual behaviors, injection drug use, and transfusion between 1978 and 1985.23,25 Heterosexual transmission has become the most common route of HIV infection among U.S. women.26
The largest (n = 73 472) study of U.S. women at prenatal or obstetrics clinics found that 0.6% were HIV positive.27 Smaller U.S. studies of pregnant women have reported prevalence rates ranging from 0.13 to 5 percent.28-30 In the United States, HIV prevalence varies by region, and minority women are more likely to be infected.26
Observational studies in the United States (all published before 1996) found that 8 to 57 percent of HIV-infected pregnant women had identifiable risk factors.31-35 Differences in the criteria used to define high-risk behaviors and varying stringency of risk factor assessment.31 could explain some of the variation in results. No study evaluated different targeted prenatal screening strategies to determine the proportion of infected women correctly identified.
In 1995, the U.S. Public Health Service36 and the American Academy of Pediatrics37 recommended prenatal counseling and voluntary HIV testing. No U.S. studies since 1995 evaluated the yield of targeted compared to universal screening. In a 7-state observational study, however, the proportion of HIV-infected women given a diagnosis before delivery increased from 70 to 80 percent between 1993 and 1996.38 In the United Kingdom, 1 observational study found an increased incidence of known HIV seropositivity after the implementation of universal prenatal testing39, but another found that 50 percent of seropositive women (identified by anonymous testing) remained undiagnosed.40
What Are the Test Characteristics of HIV Antibody Test Strategies in Pregnant Women?
The use of enzyme immunoassay followed by confirmatory Western blot or immunofluorescent assay remains the standard method for diagnosing HIV-1 infection. This method is associated with a sensitivity and specificity greater than 99 percent.41,42 False-positive diagnoses are rare, even in low-risk settings.43 The diagnostic accuracy of standard HIV testing is thought to be similar for pregnant and nonpregnant persons, although indeterminate results may occur slightly more frequently in pregnancy.44
Rapid HIV antibody tests provide results in 10 to 30 minutes, compared to 1 to 2 weeks for standard testing.45 Patients should be notified of positive rapid test results before confirmation when doing so might benefit them, such as for women with unknown HIV status presenting in active labor.46 However, this could result in unnecessary exposure to antiretroviral therapy if the rapid test result is a false positive.
Three good-quality47-49 and 4 fair-quality50-53 studies evaluated the diagnostic accuracy of rapid HIV testing during pregnancy using standard testing as the reference standard. The only study to evaluate a rapid HIV test currently in use in the United States was a good-quality prospective study of the OraQuick Advance test (OraSure Technologies, Inc., Bethlehem, Pennsylvania) on blood samples from 5744 women (prevalence, 0.59%) who presented in labor.47 The sensitivity was 100% (95% CI, 90% to 100%), the specificity was 99.9 percent (CI, 99.78% to 99.98%), the positive predictive value was 90% (CI, 75% to 97%), and the negative predictive value was 100%. In studies of nonpregnant persons, the sensitivities of currently available rapid HIV tests ranged from 96 to 100 percent, and the specificities were all greater than 99 percent.54-58 No studies have compared the diagnostic accuracy of prenatal HIV testing using home-based sampling kits or noninvasive (urine or oral) specimens with the accuracy of standard testing as the reference standard. Although 1 Indian study found a lower sensitivity with the OraQuick test on saliva than on plasma (75.0% vs. 86.4%), it did not use standard enzyme immunoassay plus Western blot as the reference standard, and local conditions may have affected saliva specimens.59
No clinical studies have evaluated the yield of repeated prenatal HIV testing, which would depend in part on the incidence of HIV infections during pregnancy.60
What Are the Harms Associated with Screening?
In a recent U.S. study of rapid HIV testing during labor, 4 of 4849 women had a false-positive rapid test result and briefly received antiretroviral prophylaxis before negative confirmatory results.47 Other evidence on the frequency and harms from false-positive diagnoses in pregnant women is anecdotal.61 but could include elective pregnancy termination based on incorrect test results, anxiety, discrimination, or altered partner relationships. False-negative and true-negative test results could encourage continued risky behaviors. Data on rates and consequences (such as anxiety) of indeterminate tests in pregnant women are lacking.62
True-positive tests can also result in anxiety, depression, social stigmatization, changes in relationships with sexual partners, and discrimination.37,63 Most studies of harms from testing have been performed in nonpregnant populations. One small (n = 40) study of prenatal testing among U.S. women found statistically significantly higher anxiety and depression scores among HIV-positive women compared with matched uninfected controls, as well as a nonsignificant trend toward increased partnership dissolution.64 A recent good-quality cohort study found that receiving a prenatal HIV diagnosis did not increase risk for intimate partner violence.65 Data are insufficient to estimate suicide risk associated with prenatal diagnosis of HIV.66
Is Screening Acceptable to Pregnant Women?
Because mandatory testing of pregnant women could result in avoidance of prenatal care.67, there remains general consensus that HIV testing should be voluntary and performed after obtaining of informed consent.23 A good-quality systematic review found that acceptance rates for HIV testing among more than 174,000 pregnant women in 25 studies published through 1995 ranged from 23 percent to 100 percent.68 More recent data from 16 U.S. states and 5 Canadian provinces found a similar range of testing uptake (25% to 98%).69 A large U.S. survey found that overall prenatal testing rates increased from 41 percent in 1995 (when recommendations for universal prenatal HIV counseling and testing were issued) to 60% in 1998.70
Several factors appear to influence testing rates. One randomized trial found that prenatal testing rates were significantly higher in women offered HIV testing (35%) than in those not receiving a direct offer (6%).71 Strong provider endorsement of testing also increased uptake.72,73 Testing rates were generally higher in states and Canadian provinces that used an "opt-out" policy (in which women are informed that an HIV test is a standard part of prenatal care and that they may decline it) than in those that used an "opt-in" policy (in which women are required to specifically consent to an HIV test)—71 percent to 98 percent compared with 25 percent to 83 percent.69 Noncomparative studies also reported high (85% to 88%) uptake rates with opt-out testing.71,74,75 We identified no studies evaluating the effect of anonymous versus name-based testing on prenatal screening rates, or the effects of streamlined or targeted counseling.
Newer screening methods, such as home sample collection, rapid tests, and noninvasive sampling, could increase rates of prenatal HIV testing.45 A recent U.S. observational study of pregnant women in labor found that 84 percent accepted rapid testing.47 We identified no studies evaluating the effect of oral sampling or home-based collection on acceptance of prenatal HIV testing.
How Many HIV-Infected Pregnant Women Who Meet Criteria for Interventions Receive Them?
In a large U.S. study, 91 percent (3690 of 4062) of tested pregnant women received their results.76 One randomized trial from Africa found that rapid testing increased notification rates compared with standard testing (96% vs. 65%) among pregnant HIV-positive women.77
Several recent U.S. studies found that HIV-infected women used antiretroviral drugs in more than 90 percent of pregnancies, with a trend toward increased combination regimen use (58% to 80% from 1998 to 1999).78-82 In 1 U.S. study of rapid testing, all HIV-infected pregnant women (n = 18) who were given a diagnosis during active labor in time to administer intrapartum zidovudine received the drug.47 In recent large U.S. observational studies, scheduled cesarean section rates for HIV-positive women ranged from 37 to 50 percent.78,81,83
How Effective Are Interventions in Reducing Mother-to-Child Transmission Rates or Improving Clinical Outcomes in Pregnant Women with HIV Infection?
Antiretroviral Agents
In the absence of antiretroviral prophylaxis, the risk for mother-to-child transmission of HIV is 14 to 25 percent in developed countries and 13 to 42 percent in countries with high rates of breastfeeding.84 The landmark Pediatric AIDS Clinical Trials Group protocol 076 (PACTG 076) study found that a 3-phase maternal and infant zidovudine regimen in nonbreastfeeding women starting at 14 to 34 weeks' gestation (median, 26 weeks' gestation) through 6 weeks postpartum decreased the risk for transmission from about 25 percent to 8 percent compared to placebo.85 A good-quality systematic review of zidovudine monotherapy clinical trials found that any zidovudine regimen (including shorter courses and in breastfeeding women) significantly reduced the risk for mother-to-child transmission compared to placebo (odds ratio, 0.46 [CI, 0.35 to 0.60]).86 Zidovudine was also associated with decreased risk for infant death within the first year (odds ratio, 0.57 [CI, 0.38 to 0.85]) and stillbirth (relative risk, 0.31 [CI, 0.11 to 0.90]).
In the United States, treatment of seropositive pregnant women has evolved to multidrug regimens, including highly active antiretroviral therapy, or HAART (>3 drugs, usually from >2 classes).17 The only randomized trial of full-course combination regimens (nelfinavir or nevirapine plus zidovudine) during pregnancy was discontinued early because of a high rate of treatment-limiting or serious side effects in the nevirapine group.87 Four large U.S. or European cohort studies (3 good-quality, 1 fair-quality) evaluated the relative effectiveness of antiviral regimens with 2 or more drugs versus 1-drug regimens or no antiretroviral agents in nonbreastfeeding women (Table 1).82,88-90 In all 4 studies, regimens with more antiretroviral drugs were superior to regimens with fewer antiretroviral drugs for preventing mother-to-child transmission (Table 2). The only study that specifically compared the effectiveness of HAART regimens with that of no antiretroviral agents reported an adjusted odds ratio of 0.13 (CI, 0.06 to 0.27) for prevention of mother-to-child transmission.89
The addition of single-dose intrapartum (maternal) and postpartum (infant) nevirapine to antiretroviral regimens initiated before 34 weeks' gestation was evaluated in 2 good-quality randomized, controlled trials performed in nonbreastfeeding settings (Table 3).91,92 One trial found that the addition of single doses of intrapartum and postpartum nevirapine to a slightly abbreviated (28 weeks' gestation to 1 week postpartum) course of zidovudine alone reduced mother-to-child transmission from 6.3 percent to 1.9 percent.92 In contrast, an earlier trial found that the addition of single-dose intrapartum and postpartum nevirapine therapy to primarily (77%) combination antiretroviral regimens did not further decrease already low transmission rates (1.4% to 1.6%).91
Shorter courses of antiretroviral prophylaxis started after 34 weeks' gestation have primarily been evaluated for use in resource-poor countries. Although shorter courses may be associated with an increased risk for antiretroviral drug resistance, they may be considered for use in U.S. women who did not receive a diagnosis early enough to receive a full course. In general, shorter courses were less effective than full courses, although they did reduce transmission rates (Table 3).93-97 Even very abbreviated regimens administered during labor were associated with some reduction in transmission.98-102 Neonatal prophylaxis alone was less effective than regimens that included maternal prophylaxis.99
A recent good-quality prospective observational study of HIV-positive women who were given a diagnosis through rapid testing during labor and were treated with zidovudine with or without nevirapine found a transmission rate of 9 percent (3 of 32).47
No studies have evaluated clinical progression, death, quality of life, or horizontal transmission associated with different antiretroviral regimens for HIV-infected women identified during pregnancy.
Avoidance of Breastfeeding
Two meta-analyses of observational studies found that breastfeeding was associated with an overall increased rate of mother-to-child transmission of HIV of 14 to 16 percent.9,103 In another recent meta-analysis.104, the rate of late (beyond 4 weeks postnatal) transmission was 9.3 percent after 36 months.
No randomized, controlled trials have evaluated the rate of mother-to-child transmission associated with breastfeeding in the United States or in women receiving antiretroviral therapy. One large, good-quality prospective Italian cohort study of 3770 children found that breastfeeding significantly increased transmission rates after adjustment for other factors, including antiretroviral use (adjusted odds ratio, 10.20 [CI, 2.73 to 38.11]).88 An African trial among women not receiving antiretroviral agents found that breastfeeding was associated with a probability of mother-to-child transmission of 36.7 percent (CI, 29.4% to 44.0%) at 24 months compared with 20.5 percent (CI, 14.0% to 27.0%) with formula feeding, and a mortality rate of 24.4 percent (CI, 18.2% to 30.7%) compared with 20.0 percent (CI, 14.4% to 25.6%), respectively.105
Elective Cesarean Section
One good-quality European cohort study evaluated the effectiveness of elective cesarean section in the HAART era.89 The rate of mother-to-child transmission was 1.6% in women delivering by elective cesarean compared with 6.5 percent in those delivering vaginally, with an odds ratio (adjusted for antiretroviral therapy, prematurity, and maternal CD4 cell count and viral load) of 0.33 (CI, 0.11 to 0.94). In the subgroup of women receiving HAART, the odds ratio was 0.64 (CI, 0.08 to 5.37) for elective cesarean compared to vaginal delivery, and in the subgroup with undetectable viremia, the odds ratio was 0.07 (CI, 0.02 to 0.31) for elective cesarean compared to vaginal or emergency cesarean delivery.
Other studies of elective cesarean section were conducted before the widespread use of combination antiretroviral regimens. One good-quality European randomized clinical trial found a mother-to-child transmission rate of 10.5 percent in women randomly assigned to vaginal delivery compared with 1.8 percent in those randomly assigned to elective cesarean section (P = 0.009).106 Among 119 babies delivered to women who received zidovudine and underwent cesarean section, the rate of HIV infection was 0.8 percent. A good-quality meta-analysis of 15 prospective cohort studies found a 50-percent reduction in the likelihood of mother-to-child transmission with elective cesarean section compared to other modes of delivery (odds ratio, 0.43 [CI, 0.33 to 0.56]).107 The benefits of elective cesarean section were additive with zidovudine exposure; the likelihood of transmission was reduced by approximately 87 percent with both interventions compared to nonelective cesarean section or vaginal delivery and no antiretroviral agents (adjusted odds ratio, 0.13 [CI, 0.09 to 0.19]). A meta-analysis of 7 prospective cohort studies108 found that cesarean section (elective or nonelective) was associated with a lower risk for transmission in women with viral loads less than 1000 copies/mL; however, the overall transmission rate was low (3.6%) and was reduced by antiretroviral agents alone to about 1 percent.
How Does Identification of HIV Infection in Pregnant Women Affect Future Reproductive Choices?
Knowledge of HIV status could affect future reproductive choices such as contraceptive use, subsequent pregnancy, sterilization, or abortion. In 2 studies, HIV seropositivity was associated with a lower rate of pregnancy,109 or a trend toward a lower rate,110 than in uninfected women, but another study found an increasing rate of pregnancy among HIV-infected women.111 One U.S. study found that 27 percent of HIV-infected women chose tubal ligation compared with 15 percent of uninfected controls, and oral contraceptive use was less likely in seropositive women.110 Two other noncomparative U.S. studies reported rates of tubal ligation among HIV-infected women of 24 percent and 27 percent.38,112 An African study found that single-session postpartum counseling did not appear to influence decisions on condom use or reproductive behavior.113 In 2 U.S. studies, pregnancy termination rates did not differ between HIV-infected and uninfected women.64,114
What Are the Harms Associated with Antiretroviral Drugs and Elective Cesarean Section?
Maternal Harms from Antiretroviral Drugs
Antiretroviral exposure during pregnancy is associated with significant short-term nonobstetric adverse events, but these often resolve after therapy with the offending drug or drug combination is discontinued; in addition, effective alternatives are usually available.17 Guidelines reviewing adverse events associated with specific antiretroviral drugs, classes, and combinations in pregnancy are regularly updated, and specific antiretroviral drugs and combinations associated with serious complications are not recommended or should be used only with caution.17,115
One good-quality meta-analysis found that zidovudine exposure during pregnancy did not cause any deaths or long-term maternal adverse events.86 The largest (n = 1407) prospective study of combination antiretroviral therapy found that gestational diabetes was the only associated adverse event; it occurred most frequently with regimens that included a protease inhibitor.116 Although continuous nevirapine therapy is associated with serious hepatic and cutaneous adverse events,87,117-119 no laboratory or clinical evidence of liver toxicity with single-dose intrapartum nevirapine has been reported.92,98,100
Another potential harm of antiretroviral therapy initiated during pregnancy is the development of drug resistance, particularly in women who receive single-dose nevirapine or regimens that do not fully suppress viral replication.120 No studies have evaluated the effects of limited exposure to combination antiretroviral agents during pregnancy on long-term clinical outcomes.121 Studies examining the effect of limited exposure to zidovudine alone did not find a negative impact on disease progression or response to later therapy.122-124 The only study that evaluated the impact of nevirapine resistance mutations125-127 after single-dose intrapartum exposure found that women who received intrapartum nevirapine were less likely to have complete virologic suppression after 6 months of postpartum treatment with a nevirapine-containing regimen (49% vs. 68%).128 CD4 cell count response and degree of weight loss, however, did not significantly differ between groups receiving and not receiving intrapartum nevirapine, although longer followup is needed.
Maternal Harms from Elective Cesarean Section
Cesarean section is associated with an increased risk for maternal complications compared to vaginal delivery, although elective surgery is safer than an emergency cesarean section.129 Women with HIV infection are at higher risk for cesarean section—related complications than uninfected women.130,131
One randomized, controlled trial found that the rate of postpartum fever was 1.1 percent (2 of 183) in HIV-infected women delivering vaginally and 6.7% percent (15 of 225) in those having a planned cesarean section, but no serious complications occurred in either group.106 The largest (n = 1186) prospective observational study found that elective cesarean section was associated with increased rates of postpartum fever (14.3%; relative risk, 4.16 [CI, 1.99 to 8.70]), hemorrhage (7.1%; relative risk, 1.58 [CI, 0.58 to 4.26]), endometritis (5.4%; relative risk, 2.57 [CI, 0.78 to 8.51]), urinary tract infection (5.4%; relative risk, 3.64 [CI, 1.06 to 12.54]), and any postpartum morbidity (26.7%; relative risk, 2.62 [CI, 1.61, 4.20]) compared to vaginal delivery.132 A smaller prospective study reported similar findings.133
Harms Associated with In Utero Exposure to Antiretroviral Drugs
The U.S. Food and Drug Administration classifies the in utero safety of antiretroviral drugs, but for most drugs data are limited or are based on animal studies.134 One good-quality U.S. meta-analysis of 5 prospective cohort studies and 1 good-quality, large European prospective cohort study found no significant differences in the rates of congenital anomalies, neonatal conditions, or low birthweight between infants exposed to any combination of antiretroviral agents and unexposed infants.15,135 Data on the association between combination antiretroviral regimens and increased rates of premature delivery are mixed. A recent large prospective cohort study found an increased rate of premature birth associated with combination regimens (adjusted odds ratio, 4.14 with a protease inhibitor and 2.66 without a protease inhibitor compared to no treatment) 136 but an earlier meta-analysis found no increased risk.135
Although molecular and biochemical evidence of mitochondrial dysfunction have been reported in infants exposed in utero to antiretroviral agents,137-139 the clinical impact of such dysfunction is unclear.140,141 Observational studies have found no clear evidence of clinical symptoms15,137,142 or deaths 143-145 due to mitochondrial dysfunction among uninfected infants exposed to HAART in utero.
Long-term (4 to 6 years) studies of adverse events from in utero antiretroviral exposure are available only for zidovudine. One good-quality meta-analysis and 1 good-quality prospective cohort study found no increase in long-term clinical adverse events or changes in growth or development in exposed infants up to 4 years of age,86,146 and no tumors or deaths from cancers after 6 years.147
Estimates of Numbers Needed To Screen
Table 4 estimates the outcomes of one-time prenatal screening before the third trimester in 3 hypothetical cohorts (0.15% prevalence, 0.30% prevalence, and 5% prevalence [high risk]) of 10,000 nonbreastfeeding pregnant women, using the highest-quality and most applicable evidence (go to the Appendix Table for base-case assumptions). In settings with a maternal prevalence of 0.15 percent, the estimated NNS to prevent 1 case of mother-to-child transmission ranged from 3500 to 12,170; in a cohort of high-risk patients, the NNS ranged from 105 to 365. There were insufficient data with which to estimate the long-term benefits of screening on maternal disease progression or other clinical outcomes (such as horizontal transmission).
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Discussion
No published studies directly link prenatal screening for HIV with clinical outcomes. Other evidence obtained for the systematic review (summarized in Table 5) indicates that testing is extremely accurate, uptake of recommended interventions is high, and perinatal transmission can be reduced from 14 percent to 25 percent without interventions to 1 percent to 2 percent.
Targeted prenatal screening for HIV according to risk factor assessment would miss a substantial proportion of infected women who report no risk factors. Although universal screening in low-prevalence settings could lead to thousands of women being tested for each case of perinatal HIV prevented, a high priority is placed on prevention of perinatal HIV infection in the United States. Several U.S. expert panels recommend universal prenatal HIV screening.7,148,149
Despite the tremendous efficacy of interventions for preventing mother-to-child transmission of HIV infection, uptake of HIV screening and use of antiretroviral therapy remain incomplete in the United States. Data indicate that use of "opt-out" testing policies could improve uptake rates, and use of rapid tests could facilitate timely interventions for persons testing positive.
The case for universal prenatal screening would be further strengthened by data showing improvements in long-term maternal or other outcomes, such as horizontal transmission, future reproductive choices, or risky behaviors. Other important areas requiring additional study include clinical trials to identify optimal combination antiretroviral regimens, methods to improve uptake of screening and recommended interventions, and methods to improve access to screening. In addition, further studies to determine the risk for potential harms from prenatal screening, such as intimate partner violence and methods to minimize those risks, are needed. Additional studies assessing long-term maternal outcomes and effects of brief, interrupted, or less intensive antiretroviral regimens on future response to HAART and long-term maternal and infant risks from antiretroviral exposure will also help further clarify risks and benefits of interventions.
Perinatal HIV infection is a largely preventable disease. Despite major reductions in the incidence of perinatal HIV infection in the U.S. since the early 1990s, more thorough uptake of prenatal testing and use of recommended interventions could reduce the incidence further.
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