In February 1994, the Pediatric AIDS Clinical Trial Group Protocol 076 demonstrated that zidovudine (ZDV) could reduce the risk of mother-to-child HIV transmission from 25% to 8% (1). As a result, a United States Public Health Service (USPHS) task force issued recommendations in August 1994 for the use of ZDV to reduce perinatal HIV transmission. Included are treatment options for HIV-infected pregnant women and for infants born to HIV-infected women and recommendations for the medical monitoring of pregnant women and of infants who receive ZDV (2). In July 1995, the USPHS published recommendations for HIV counseling and voluntary testing for all pregnant women, which include advice to health care professionals on educating women about the importance of knowing their HIV status and the steps to preventing mother-to-child transmission (3). Revised recommendations for HIV screening for pregnant women, which further emphasized HIV testing as a routine part of prenatal care, including rapid testing during labor and delivery, were published in 2001 (4).

After the recommendations were published in 1995, CDC began conducting enhanced perinatal surveillance activities in 7 states to monitor the effect of the guidelines. Prevention indicators were assessed for the years before, during, and after the implementation of the guidelines (1993, 1995–1996). These indicators included receipt of prenatal care, HIV testing before or during pregnancy, and administration of ZDV to the mother antepartum and intrapartum and to the infant after birth. Data showed that an increased number of pregnant women and infants received ZDV after the recommendations were published. The proportion of infants infected with HIV decreased from 16% of those who did not receive ZDV to 8% of those who received ZDV (5).

In 1999, the Institute of Medicine issued a report entitled Reducing the Odds: Preventing Perinatal Transmission of HIV in the United States. In this report, the committee described factors that lead to perinatal transmission. They include the lack of prenatal care, HIV testing, and antiretroviral therapy (ART) for HIV-infected women and HIV-exposed infants (6). Also in 1999, Congress appropriated $10 million per year for activities aimed at reducing perinatal HIV infection. These activities included enhanced perinatal HIV surveillance, funded in 24 state and local health departments (Figure1); perinatal HIV prevention programs, funded in 16 state health departments; and partnerships with 6 national organizations (Figure 1).

CDC implemented activities to further reduce perinatal transmission in areas with high prevalence. The Enhanced Perinatal Surveillance (EPS) project was created as an extension of routine surveillance activities. The overall goals of EPS are to (a) monitor the implementation of the USPHS recommendations for counseling and voluntary testing of pregnant women, the use of ZDV to prevent perinatal HIV transmission, and the effect of implementation on the trends of HIV disease among children; (b) to establish a surveillance system to collect data that enable states to respond to selected requirements of the Ryan White CARE Act; and (c) to assist in timely evaluation of perinatal prevention efforts.

The data in this report represent the 24 sites conducting EPS for live births during 1999–2001 (Figure 1). As of September 2003, a total of 8577 mother-infant pairs, representing 8448 pregnancies, had been reported to EPS. The report, comprising data for birth years 1999–2001, is organized in 3 sections: (a) demographic, behavioral, and clinical information on HIV-infected pregnant women who gave birth; (b) demographic, behavioral, and clinical information on those women, by race/ethnicity; and (c) clinical information on infants born to HIV-infected women. EPS methods are described in the Technical Notes.

The purpose of this report is to describe the population of HIV-infected women who gave birth during the years 1999, 2000, and 2001. These data provide essential information for further focusing perinatal prevention efforts in the United States. The data are presented by child’s birth year so that readers can understand the characteristics of this population in a particular year. However, readers are cautioned against comparing the data for the birth years, as not all sites contributed data for all 3 years.

An estimated 6000 to 7000 HIV-infected women gave birth in the United States during the year 2000: an estimated 280–370 infants were infected (7). According to EPS data, 1 in 8 HIV-infected women did not receive prenatal care, and 1 in 9 was not tested for HIV before giving birth. One of the goals of Advancing HIV Prevention, CDC’s recently launched initiative, is to further decrease perinatal HIV transmission (8). Strategies for accomplishing this goal include (a) working with prevention partners to disseminate recommendations and support implementation, (b) providing training for providers and health departments in conducting prenatal testing, (c) promoting universal prenatal HIV screening according to the opt-out approach (HIV testing is part of the routine battery of prenatal tests unless a woman declines), and (d) promoting routine rapid testing during labor and delivery for women whose HIV status is still unknown. These and other strategies will be necessary to further reduce perinatal HIV transmission in the United States.

Highlights

• Most (86%) of the HIV-infected pregnant women reported to EPS were of races other than white: 69% were black, 16% were Hispanic, and 1% were Asian/Pacific Islander (Table 1).
• Over one half (54%) of the HIV-infected women were exposed to HIV through heterosexual contact (Table 1).
• Most (88%) of the HIV-infected women received some prenatal care. Of this proportion, 82% had made > 3 visits. Of the total, 8% received no prenatal care. Receipt of prenatal care was unknown for 4% (Table 2).
• The mother’s HIV status was known before the birth of 90% of the reported HIV-exposed infants (Table 3).
• Of the mother-infant pairs, 79% received ART during the prenatal period, and 77% received ART during labor. Of the infants born to HIV-infected women, 92% also received ART during the neonatal period (Table 4).
• One third (31%) of the HIV-infected women had an elective cesarean section (Table 5).
• One fifth (20%) of the HIV-infected women had used illicit drugs during pregnancy (Table 6).
• By race/ethnicity, the following proportions of HIV-infected women received prenatal care: 92% of white women, 91% of Hispanic women, and 87% of black women (Table 9).
• Similar proportions of HIV-infected women, by race/ethnicity, were tested before or during pregnancy: 91% of white women, 91% of black women, and 89% of Hispanic women (Table 10).
• ART during the prenatal period was received by 86% of white women, 81% of Hispanic women, and 78% of black women (Table 11).
• ART during labor was received by 82% of white women, 78% of Hispanic women, and 76% of black women (Table 11).
• Similar proportions of infants, categorized by mother’s race/ethnicity, received ART after birth: 93% of infants born to white women, 92% of those born to Hispanic women, and 92% of those born to black women (Table 11).
• Of the 8448 HIV-infected women, 96% gave birth to 1 child (Table 14).
• Of the 8577 infants born to HIV-infected women, 397 (5%) were perinatally infected with HIV, 5468 (64%) were not infected, and 2712 (32%) remain in the indeterminate category (Table 16).

References

• Conner EM, Sperling RS, Gelber R, et al. Reduction of maternal-infant transmission of human immunodeficiency virus type 1 with zidovudine treatment. N Engl J Med 1994;331:1173–1180.
• CDC. Recommendations of the U.S. Public Health Service Task Force on the use of zidovudine to reduce perinatal transmission of human immunodeficiency virus. MMWR 1994;43(No. RR-11):1–20.
• CDC. U.S. Public Health Service recommendations for human immunodeficiency virus counseling and voluntary testing for pregnant women. MMWR 1995;44(No. RR-7):1–15.
• CDC. Revised guidelines for HIV counseling, testing, and referral and revised recommendations for HIV screening of pregnant women. MMWR 2001;50(No. RR-19):59–85.
• CDC. CDC report regarding selected public health topics affecting women’s health. MMWR 2001;50(No. RR-6):17–28.
• Institute of Medicine, National Research Council. Reducing the Odds: Preventing Perinatal Transmission of HIV in the United States. Washington, DC: National Academy Press; 1999.
• Fleming P, Lindegren ML, Byers RH, et al. Estimated number of perinatal HIV infections, United States, 2000. In: Program and abstracts of the XIV International Conference on AIDS; July 7–12, 2002; Barcelona, Spain. Abstract TuPeC4773.
• CDC. Advancing HIV Prevention: new strategies for a changing epidemic—United States, 2003. MMWR 2003;52(No. 15):329–332.

Suggested Reading

CDC. Current trends: classification system for human immunodeficiency virus (HIV) infection in children under 13 years of age. MMWR 1987;36:225–230, 235.

CDC. 1994 Revised classification system for human immunodeficiency virus infection in children less than 13 years of age; official authorized addenda: human immunodeficiency virus infection codes and official guidelines for coding and reporting ICD-9-CM. MMWR 1994;43(No. RR-12):1–19.

CDC. Update: perinatally acquired HIV/AIDS—United States, 1997. MMWR 1997;46(No. 46):1086– 1092.

CDC. Success in implementing Public Health Service guidelines to reduce perinatal transmission of HIV— Louisiana, Michigan, New Jersey, and South Carolina, 1993, 1995, and 1996. MMWR 1998;47:688–691.

Lindegren ML, Byers RH, Thomas P, et al. Trends in perinatal transmission of HIV/AIDS in the United States. JAMA 1999;282:531–538.