Natural killer cell activity during pregnancy

Natural killer cell activity was found to be depressed from the early period of pregnancy to the third trimester, as compared to that in the nonpregnant state. Natural killer cell activity in the puerperium tended to be depressed slightly more than during pregnancy. There were no differences in activity between toxemic and normal pregnant women in the same gestational week. A retrospective survey showed a negative correlation between natural killer cell activity during pregnancy and the birth weight of the baby. Although the role of natural killer cells during pregnancy needs to be more clearly elucidated, they may be involved in fetal growth.