Cellular immunity in preeclampsia: alterations in T-lymphocyte subpopulations during early pregnancy.

T-lymphocyte subpopulations were evaluated longitudinally in 62 primigravidas. Beginning early in the second trimester, women who later developed preeclampsia showed a significantly lower proportion of T-helper cells compared with those who remained normotensive (27.0 +/- 7.1 versus 34.7 +/- 7.9%; P less than or equal to .001). The decrease in the T-helper cell count occurred several weeks before the development of preeclampsia and reverted to normal 6-10 weeks postpartum.