The Survey of Childbearing Women (SCBW) has been conducted by the Texas Department of Health (TDH) each year since 1988, with the exception of 1996. The SCBW is an HIV prevalence survey of resident Texas women who delivered a live birth within a given sampling period. It is the largest and least biased of all HIV surveys conducted in Texas because it includes women of all races, ethnicities, and socioeconomic strata. The SCBW does not, however, reflect HIV prevalence among all females as it is limited to women of childbearing age, who delivered a live birth during the survey interval.
The 1997 SCBW was funded entirely by the State of Texas. TDH conducted this survey in accordance with the Centers for Disease Control and Prevention's (CDC) protocol, HIV Seroprevalence Survey in Childbearing Women: Testing Neonatal Dried Blood Specimens for Maternal HIV Antibody, published in June 1992. HIV antibody prevalence among Texas mothers is determined by testing surplus blood spots obtained from their newborn infants as part of a statewide screening program for metabolic and genetic diseases. During pregnancy, a mother's antibodies are transferred to the infant who is unable to make his or her own antibodies until a number of months after birth. Thus, the SCBW reflects the mother's HIV antibody status and not that of the infant.
From 1988 through 1991, the survey interval for each year was four months (April 1-July 31). For the years 1992 through 1994, the surveys were extended to nine months to better measure the spread of HIV in areas of Texas with lower prevalence. In 1995, the survey was halted after three months due to congressional concerns over the use of blinded surveys and the CDC's consequent cessation of funding for such studies. With no CDC funds available, there was no SCBW conducted in 1996. In 1997, the study resumed, this time using State of Texas funds, and again used a three month survey interval.
A total of 83,992 women were tested in the 1997 SCBW. As with the 1995 survey, this is a significantly smaller sample than those collected from 1992 through 1994 when the survey was conducted on births occurring during nine-month intervals. These smaller sample sizes reduce the number of HIV-positives identified and, therefore, some areas and groups show no positives detected. It should be noted that the absence of a positive result in this survey does not necessarily indicate the absence of HIV infection within that particular area or group.
In 1997, SCBW data indicated an overall rate of 1.05 positive HIV results per 1000 women tested. This was slightly higher than the 1995 rate (0.93 per 1000) and identical to the rate found in the 1994 survey (Figure 1). The rate for African American women reached an all-time high in 1997 (6.93 per 1000), this continues to run much higher than the rates of other racial/ethnic groups. The rate for Hispanic mothers was up only slightly from 1995 (0.48 per 1000, up from 0.43), but this represents the highest rate seen for this group since 1988. Women of all other races/ethnicities, which includes those of unknown race/ethnicity, also displayed a record high rate in the 1997 survey (0.84 per 1000). White women were the only group to experience a reduction in HIV rate, dropping to a record low of 0.23 cases per 1000 tested (Table 1).
Among the six most populous counties (Bexar, Dallas, El Paso, Harris, Tarrant, and Travis), Harris showed the highest HIV rate at 3.06 cases per 1000 women tested. The rate in Harris County was more than twice that of the second highest county (Dallas at 1.18 per 1000), and nearly six times the rate the third highest county (Bexar at 0.52). Looking at the breakdown for racial/ethnic groups in these counties, the HIV-infection rate was highest for African American women in Harris (12.61), Dallas (4.84), and Bexar Counties (3.64). African American women also had a high rate outside of the six most populous counties, with a rate of 4.72 cases per 1000 tested. Rates for Hispanic women were highest in Harris County (1.60), followed by Travis County (0.92). The highest rate for White women was also found in Harris County (0.62), but among these six counties, only Harris and Dallas Counties detected any HIV-positive White women. At least one HIV-positive mother was found in each of the six most populous counties (Table 2).
Women between the age of 20 and 24 had the highest HIV-positive rate at 1.29 per 1000 tested. Age groups 15-19 and 25-29 tied for the second highest rate (0.86 per 1000). No positives were detected for any mothers under the age of 15 or over the age of 40 (Table 3). Age specific rates calculated from this survey may be imprecise due to the number of cases in which the mother's age was missing: 10 percent overall and 26 percent of those mothers testing positive for HIV.
Studies like the SCBW that monitor HIV prevalence in women are important because without medical intervention, 20 to 25 percent of infants born to HIV-infected mothers become HIV-infected. Drug therapy studies have revealed that treating HIV-infected women during pregnancy with zidovudine (AZT) can reduce the infant infection rate to as low as 8 percent. AZT treatment of an HIV-infected mother at the time of delivery can also reduce the chances of HIV transmission to the newborn. Although neonatal screening and treatment with AZT could reduce the number of HIV infections in newborns, prenatal testing combined with AZT treatment offers the best opportunity for preventing neonatal HIV infections. Armed with this knowledge, the Texas Legislature passed House Bill 1345 in 1995. This bill requires health care providers to test every consenting pregnant woman for HIV at her initial prenatal examination and the at time of delivery.
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