Figure 5.

Infant antitetanus IgG group means as a percentage of dam group means. (A) Overall, the TT IgG level among the infants in each experimental group was a small percentage (5% to 33%) of the respective dam TT IgG levels. In addition, gross visual examination of these data suggests a cutoff value for prenatal transfer of TT-specific IgG to offspring. (B) Maternal TT IgG levels were inversely related to the ratio of infant-to-dam TT IgG levels (R₅₀ = –0.68, P < 0.0001), suggesting that higher maternal TT IgG levels are associated with less efficient transfer of TT-specific maternal antibodies to the fetus during late gestation.