Effect of pregnancy on the natural history of HIV infection

In pregnancy, immune function is suppressed in both HIV-infected and uninfected women^5,62,63. There is a decrease in immunoglobulin, reduced complement levels in early pregnancy and a more significant decrease in cell-mediated immunity during pregnancy. These normal changes during pregnancy have led to concern that the effect of pregnancy among HIV-infected women could be to accelerate the progression of the infection. Early reports of pregnancy in HIV-infected women seemed to support this^64,65. Prospective follow-up studies have not confirmed these findings to date. One French study followed 57 HIV-infected women who completed a pregnancy and 114 who had never been pregnant, with a mean follow-up of 61 months. There was no difference in the rate of acceleration of disease between the groups⁶⁶. An Edinburgh study showed no effect of pregnancy on marker paths of HIV infection in 145 women followed between 1985 and 1992⁶⁷. A further study from Switzerland followed 32 HIV infected pregnant women who had preconception CD4 cell counts and compared their disease progression with 416 HIV infected women who did not have a pregnancy. Women were matched for age and CD4 cell count at entry. Mean follow-up time was 4.8 years for the pregnant women and 3.6 years for the controls. There was no overall difference in the rate of death between the two groups nor in the rate of progression to any AIDS defining event, except that HIV infected women with pregnancies were significantly more likely to develop bacterial pneumonia than their never-pregnant controls⁶⁸.

Several other studies have shown similar results^{63,69,70,71,72,73}. Pregnancy had little effect on viral load in an American study⁷⁴. Pregnancy appears to have little effect on the progress of infection in asymptomatic HIV-positive women or in those with early infection, although there may be more rapid progression in women with late stage HIV infection^75,76,77.

African women do not appear to experience more rapid progression of HIV infection during their pregnancies, despite the additional factors of repeated pregnancies, other infections and poor nutrition. African research does not support the existence of a short-term synergistic effect on the immune system between pregnancy and HIV infection. In a Kenyan study, the difference in the changes over pregnancy in CD4+ and CD8 cells and their ratio were not statistically significant between HIV-positive and negative women⁷⁸. CD4+ and CD8 percentages were shown to be stable in HIV sero-positive women in late pregnancy and the postpartum period in a Malawi study, demonstrating little effect of pregnancy on immune status⁷⁹.

In some central African countries, AIDS has become a common cause of maternal mortality, as the epidemic has progressed^80,81. This does not appear to be due to pregnancy-induced acceleration of the HIV-related conditions but to more women with advanced disease becoming pregnant, with resultant higher rates of HIV complications.