Is zidovudine therapy in pregnant HIV-infected women associated with gestational age and birthweight?
OBJECTIVE
Prophylactic zidovudine during pregnancy and labour reduces maternal viral load and, with neonatal therapy, has been shown to reduce vertical transmission. However, zidovudine may have additional effects. Advanced HIV disease is associated with premature delivery, which in turn results in increased vertical transmission. Data from the European Collaborative Study (ECS) were analysed to investigate whether zidovudine could be associated with decreased prematurity risk and/or with a reduced frequency of low birthweight.


METHODS
HIV-infected pregnant women enrolled in the ECS were followed prospectively according to a standard protocol. Gestational age was assessed by ultrasound, prematurity was defined as delivery before 37 weeks and the cut-off for low birthweight was 2500 g. We calculated odds ratios (OR) to estimate the effect of zidovudine on the risk of premature of low birthweight delivery.


RESULTS
In 2299 mothers, zidovudine taken to reduce the risk of vertical transmission decreased the odds of premature delivery by a quarter (OR = 0.76, 95% confidence interval (CI) 0.53-1.09), and the odds of low birthweight by nearly half (OR = 0.55, 95% CI 0.39-0.79). Allowing for CD4 count and mode of delivery did not greatly alter these OR values. A multivariate analysis suggested that prophylactic zidovudine and prematurity were independently associated with risk of transmission.


CONCLUSIONS
Our findings suggest an additional health benefit of zidovudine. Even if most vertical transmission occurs around the time of delivery, therapy earlier in pregnancy could have an indirect effect on transmission rates through delaying delivery. This hypothesis needs to be confirmed or refuted by more appropriate studies.
Department of Epidemology and Public Health, Institute of Child Health, London, UK.
D019380:Anti-HIV Agents / Q000627:therapeutic use*; D001724:Birth Weight; D018791:CD4 Lymphocyte Count; D005260:Female; D005865:Gestational Age; D015658:HIV Infections / Q000188:drug therapy* / Q000276:immunology / Q000635:transmission; D006801:Humans; D007231:Infant, Newborn; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000188:drug therapy* / Q000276:immunology; D018894:Reverse Transcriptase Inhibitors / Q000627:therapeutic use*; D015215:Zidovudine / Q000627:therapeutic use*
D019380:Anti-HIV Agents; D018894:Reverse Transcriptase Inhibitors; D015215:Zidovudine