Science News Online (6/27/98): Cesarean + AZT = Almost no HIV transmission

 June 27, 1998 

 Cesarean + AZT = Almost no HIV transmission

by  N. Seppa

 Pregnant women with HIV, the virus that causes AIDS, can in nearly all cases 
prevent their babies from contracting the disease during birth. These mothers 
must take the drug AZT and deliver by planned cesarean section, two studies 
show.

 French scientists report that of 133 HIV-positive women who took AZT and then 
gave birth by elective cesarean before contractions started, only one 
transmitted HIV to an infant, a rate of less than 1 percent. The researchers 
had followed the progress of 2,834 HIV-positive mothers between 1985 and 1996.

 They found that babies born vaginally to 625 mothers taking AZT in this group 
contracted HIV 6.6 percent of the time. Emergency cesarean sections that were 
required by complications after contractions started in 114 other women taking 
AZT yielded an HIV transmission rate of 11.4 percent.

 Of 1,877 HIV-positive mothers not treated with AZT, 17.2 percent transmitted 
HIV to their infants. The method of birth didn't affect their risk, the 
researchers report in the July 1 Journal of the American Medical Association 
and at the 12th World AIDS Conference this week in Geneva.

 The results match those of Swiss researchers who have found in an ongoing 
study that all 42 children born by planned cesarean to HIV-positive mothers 
being treated with AZT tested negative for HIV. The Swiss findings, first 
described in the Jan. 22 AIDS, were updated this month.

 The report documented HIV infections in 20.3 percent of 271 infants born 
vaginally to mothers who were not receiving AZT. Of infants born by cesarean 
section to mothers in this group, 16.7 percent (4 of 24) were HIV-positive. 
Mothers receiving AZT passed the virus along in 8.1 percent (7 of 86) of the 
infants born vaginally.

 During vaginal childbirth, the infant can swallow blood or other fluids from 
the mother, or these fluids can come into contact with the child's mucous 
membranes or abrasions on the baby's skin, says Swiss study coauthor Christian 
Kind, a neonatologist at Kantonsspital in St. Gallen, Switzerland.

 Opportunities for infection can arise before delivery as well. Labor 
contractions place the child at risk because the placenta may leak maternal 
blood that can carry viruses to the baby. Also, if the amniotic sac surrounding 
the fetus ruptures at least 4 hours before delivery, the child can become 
exposed to HIV, Kind says. Thus, having the cesarean section before 
contractions start "is absolutely essential," he concludes.

 Although the research is valid, any public health approach that includes mass 
cesareans "has a lot of practical limitations," says Ruth E. Dickover, a 
virologist at the University of California at Los Angeles School of Medicine. 
Many women who come to the UCLA clinics arrive late in their pregnancies, have 
no health insurance to pay for a cesarean delivery, don't have an accurate due 
date, and don't know their HIV status, she says. For women in the developing 
world, prenatal care is often nonexistent, and the possibility of widespread 
cesareans is remote, she notes.

 From Science News, Vol. 153, No. 26, June 27, 1998, p. 405. Copyright O 1998 
by Science Service.

1998. AZT and C-section combo appears to nearly eliminate mother-to-child HIV 
transmission. Journal of the American Medical Association 280(July 1).

 Kind, C., et al. 1998. Prevention of vertical HIV transmission: Additive 
protective effect of elective Cesarean section and zidovudine prophylaxis. AIDS 
12(Jan. 22):205.

 Mandelbrot, L., et al. 1998. Perinatal HIV-1 transmission. Journal of the 
American Medical Association 280(July 1):55.

 Further Readings: 

 Cooper, E.R., et al. 1996. After AIDS clinical trial 076: The changing pattern 
of zidovudine use during pregnancy and the subsequent reduction in vertical 
transmission of human immunodeficiency virus in a cohort of infected women and 
their infants. Journal of Infectious Diseases 174:1207.

 Kind, C., et al. 1992. Epidemiology of vertically transmitted HIV-1 infection 
in Switzerland: results of a nation-wide prospective study. European Journal of 
Pediatrics 151:442.

 Kuhn, L., et al. 1996. Cesarean deliveries and maternal-infant HIV 
transmission: results from a prospective study in South Africa. Journal of 
Acquired Immune Deficiency Syndromes and Human Retrovirology 11:478.

 Minkoff, H., and M.J. O'Sullivan. 1998. The case for rapid HIV testing during 
labor. Journal of the American Medical Association 279(June 3):1743.