Risk factors for perinatal transmission of human immunodeficiency virus type 1 in women treated with zidovudine. Pediatric AIDS Clinical Trials Group Study 185 Team.
BACKGROUND
Maternal, obstetrical, and infant-related factors associated with the risk of perinatal transmission of human immunodeficiency virus type 1 (HIV-1) were identified before the widespread use of zidovudine therapy in pregnant women. The risk factors for transmission when women and infants receive zidovudine are not well characterized.


METHODS
We examined the effects of maternal, obstetrical, and infant-related characteristics and maternal virologic and immunologic variables on the risk of perinatal transmission of HIV-1 among 480 women and their infants, all of whom received zidovudine. The women and infants were participating in a phase 3 trial of passive immunoprophylaxis for the prevention of perinatal transmission.


RESULTS
In univariate analyses, the risk of perinatal transmission was associated with each of the following: decreased maternal CD4+ lymphocyte counts at base line; decreased maternal HIV p24 antibody levels at base line and delivery; increased maternal HIV-1 titer at base line and delivery; increased maternal HIV-1 RNA levels at base line and delivery; and the presence of chorioamnionitis at delivery. In multivariate analyses, the only independent risk factor was the maternal HIV-1 RNA level at base line (odds ratio for transmission, 2.4 per log increase in the number of copies; 95 percent confidence interval, 1.2 to 4.7; P=0.02) and at delivery (odds ratio, 3.4; 95 percent confidence interval, 1.7 to 6.8; P=0.001). There was no perinatal transmission of HIV-1 among the 84 women who had HIV-1 levels below the limit of detection (500 copies per milliliter) at base line or the 107 women who had undetectable levels at delivery.


CONCLUSIONS
Among pregnant women and their infants, all treated with zidovudine, the maternal plasma HIV-1 RNA level was the best predictor of the risk of perinatal transmission of HIV-1. Antiretroviral therapy that reduces the HIV-1 RNA level to below 500 copies per milliliter appears to minimize the risk of perinatal transmission as well as improve the health of the women.
Mofenson
L M
LM
Pediatric, Adolescent and Maternal AIDS Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA. lm65d@nih.gov
Lambert
J S
JS
Stiehm
E R
ER
Bethel
J
J
Meyer
W A
WA
Whitehouse
J
J
Moye
J
J
Reichelderfer
P
P
Harris
D R
DR
Fowler
M G
MG
Mathieson
B J
BJ
Nemo
G J
GJ
D000704:Analysis of Variance; D019380:Anti-HIV Agents / Q000627:therapeutic use*; D018791:CD4 Lymphocyte Count; D005260:Female; D015483:HIV Antibodies / Q000097:blood; D016655:HIV Core Protein p24 / Q000276:immunology; D015658:HIV Infections / Q000188:drug therapy / Q000635:transmission* / Q000821:virology; D015497:HIV-1 / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D018445:Infectious Disease Transmission, Vertical; D016015:Logistic Models; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000188:drug therapy / Q000821:virology*; D012367:RNA, Viral / Q000097:blood*; D012307:Risk Factors; D019562:Viral Load; D015215:Zidovudine / Q000627:therapeutic use*
D019380:Anti-HIV Agents; D015483:HIV Antibodies; D016655:HIV Core Protein p24; D012367:RNA, Viral; D015215:Zidovudine