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Background: Antiretrovirals (ARVs) have been effective in reducing vertical transmission of HIV. The Antiretroviral Pregnancy Registry (APR) has monitored prenatal ARV use for an early signal of teratogenicity for 25 years.
Methods: APR is an ongoing international, voluntary, prospective exposure-registration cohort study, overseen by an independent Advisory Committee. Birth defect prevalence and risk for major birth defects are estimated and compared to internal and external comparator groups. Statistical inference is based on exact methods for binomial proportions. Sufficient numbers of 1st trimester exposures have been monitored to allow detection of at least 1.5-fold increase in risk of overall birth defects for nine ARVs and a two-fold increase for six.
Results: Of the 17618 evaluable prospectively enrolled pregnancies through July 2015, there were 16699 live births (LB) with prenatal ARV exposure at any time during pregnancy and 473 birth defects for overall prevalence of 2.8 defects/100 live births (95% confidence interval (CI): 2.6, 3.1). Among 7738 1st trimester exposures to ARVs, 221 birth defects were reported, with a prevalence of 2.9% (95% CI: 2.5, 3.3). Among 8959 2nd/3rd trimester exposures to ARVs, there were 250 birth defects, with a prevalence of 2.8% (95% CI: 2.4, 3.2). Prevalence Ratio comparing 1st vs 2nd/3rd trimester exposures was 1.02 (95% CI: 0.86, 1.22).
Conclusions: To date the overall birth defect prevalence in APR has not been significantly different from two population based surveillance systems: 2.72/100 live births reported in the Metropolitan Atlanta Congenital Defects Program (MACDP, Centers for Disease Control and Prevention); and 4.17/100 LB from the Texas Birth Defects Registry (TBDR, Texas Department of State Health Services); or the APR internal comparator of 2nd/3rd trimester exposures. For didanosine and nelfinavir a modest, statistically significant increase in prevalence is noted when compared to MACDP but not TBDR. The APR independent Advisory Committee concludes “The Antiretroviral Pregnancy Registry finds no apparent increases in frequency of specific defects with first trimester exposures and no pattern to suggest a common cause; however, potential limitations of registries should be recognized”.