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Center for Studies of Sensory Impairment, Aging and Metabolism (CESSIAM), c/o PO Box 02-5339, Section 3163/Guatemala, Miami, FL 33102-5339
Dear Sir:
In a recent report in the Journal, Dreyfuss et al (1) exploited a luxurious array of measurements and variables in a longitudinal study of > 800 HIV-positive Tanzanian women receiving prenatal services at a health clinic in Dar es Salaam to assess the determinants of adverse pregnancy outcomes among this population. It was not surprising that the "old standbys" of low maternal weight, primiparity, and a previous preterm birth were the robust determinants of low birth weight (LBW); the evidence of significant participation of high C8 cell counts in adverse pregnancy outcomes is a novel contribution (1).
Their inquiry, however, was predicated on the statement, "Studies from the region have reported that HIV-infected pregnant women are at increased risk of delivering LBW infants, of preterm delivery, and of intrauterine growth retardation" (1), which was based on the literature review and meta-analysis of Brockelhurst and French (2). For that cohort of women in an urban setting, the prevalences of LBW, preterm delivery, and small-for-gestational-age (SGA) birth were 11.1%, 23.5%, and 11.5%, respectively (1).
Intuitively, especially with regard to LBW, these statistics do not seem to be inordinately remarkable as developing-country populations go, especially if one looks at the rural segment of such a population. For instance, in a study from Guatemala by Lechtig et al (3) that was cited by Dreyfuss et al, among 671 infants born in 4 rural ladino villages between January 1969 and February 1973, 15.2% had birth weights < 2500 g. The mean birth weight in the famous longitudinal study on the children of Santa María Cauqué by Mata (4) was 2549 ± 383 g, with a prevalence of LBW of 41.3% among 415 live, singleton births from 1964 to 1972 in that rural Mayan township. Albeit rural Guatemalan women may be much shorter in stature than urban Tanzanian women, an 11.1% rate of LBW seems by no means unreasonable. A prevalence of preterm delivery of 23.5% does indeed, however, appear to be high in urban Tanzania, but, despite the birth before 37 wk of gestation of 1 in 4 infants, most of them still came into the world weighing > 2500 g.
What might be important for our understanding of gestational HIV infection in the context of urban east Africa is whether the prevalences of the 3 index adverse outcomes (LBW, SGA birth, preterm delivery) represent an excess over the rates in an HIV-negative population of pregnant women of the same social class (or attending the same health clinic). My sense is that, at least regarding LBW prevalence, the study cohort might violate the Brockelhurst and French principle (2) and not be excessive compared with unaffected pregnancies. For all one can divine, LBW and SGA birth prevalences may be even lower among births to HIV-infected women than the community background rates. Hence, I wonder whether Dreyfuss et al could share any data on the pregnancy outcome statistics for the overall community or those for HIV-negative women in Dar es Salaam to provide a perspective on any differential adverse effect of HIV on fetal health and development in the setting of their study.
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