Detection of vertical transmission of human immunodeficiency virus type 1 by a commercial polymerase chain reaction assay

Evolución de la transmisión vertical del VIH y posibles factores involucrados

INTRODUCTION

Since the introduction of zidovudine, perinatal transmission (PT) of HIV-1 has markedly decreased, although a transmission rate of zero has still not been achieved. The present study describes the trend in PT over 13 years, as well as changes in medical-surgical management and their influence on PT.

PATIENTS AND METHODS

We performed a prospective cohort study of all HIV-1-infected mother-infant pairs born between January 1987 and December 1999 in Hospital 12 Octubre in Madrid. Univariate analysis was performed to determine the relationship between possible risk factors and PT.

RESULTS

A total of 290 mothers and 291 children were included. Thirty-eight children were infected, 28 of these before 1994 (PT rate: 13 %). There were no cases of infection when the full ACTG 076 protocol was implemented. Factors significantly associated with a higher transmission rate were prolonged rupture of membranes and nonelective caesarean section. The main protective factor was antiretroviral therapy.

CONCLUSIONS

PT markedly decreased after the introduction of the ACTG 076 protocol. In the last 13 years, maternal age and maternal infection due to heterosexual transmission have increased. Other changes observed were modifications in obstetric interventions and the generalized use of zidovudine and antiretroviral therapy during pregnancy.

[Estimate of HIV-1 infection prevalence in pregnant women and effectiveness of zidovudine administered during pregnancy in the prevention of vertical transmission]

BACKGROUND

Despite the proven efficacy of zidovudine (ZDV) for reducing perinatal transmission of HIV-1, questions remain about its implementation and effectiveness in routine practice. The aims of this study were to assess the impact of ZDV administered during pregnancy in preventing perinatal HIV-1 transmission, and to determine the proportion of early identification of maternal HIV-1 infection over time.

PATIENTS AND METHODS

We prospectively followed from birth a cohort of children born between 1/1/1987 and 31/10/1997 to HIV-1-infected mothers. Infant infection status was assessed by follow-up beyond 18 months or HIV-PCR up to 3 months of age.

RESULTS

229 mothers and 248 infants were identified in the cohort. ZDV was administered during pregnancy as monotherapy to 34 mothers for a mean of 4.7 (3.1) months prior to delivery. There were no differences in baseline characteristics between the treated and untreated groups. Mean (SD) CD4 cell count was 465 (261) cells x 10(6)/l. Factors associated with transmission were a more prolonged time of rupture of obstetric membranes (median 6 vs 1.04 hours; p = 0.023) and ZDV treatment. Among the ZDV-treated mothers only one child was infected (2.9%), whereas 37 children born to 212 untreated women became infected. (OR: 0.14; 95% CI: 0.07-0.92). The estimated prevalence of HIV-1 in pregnant women in our area is about 0.39% (95% CI: 0.34-0.45). From 1987 to 1991, 9.7% of infected women were nor identified at the perinatal period, as compared to 2.5% in the last 5 years of the study period (p = 0.034).

CONCLUSIONS

In this study, the estimated prevalence of HIV-1 infection is high. ZDV during pregnancy is significantly associated with a decrease in perinatal transmission in our setting. The awareness of an effective treatment might have contributed to the increased identification of HIV-infected mothers prior to delivery observed over time in our cohort of children born to HIV-infected mothers.