The T cell-mediated immune response to human cytomegalovirus (HCMV) after primary infection, as well as the determinants of intrauterine transmission, are poorly understood.Sequential peripheral blood leukocyte samples from 74 pregnant women and 29 nonpregnant individuals with primary infection were examined for HCMV-specific CD4+ T cells by cytokine flow cytometry (CFC) and lymphoproliferative response (LPR) analysis. Immunological results for 19 transmitter and 21 nontransmitter mothers were compared.Comparison of CFC and LPR analysis results showed that (1) there was no difference between pregnant and nonpregnant individuals; (2) HCMV-specific CD4+ T cells were detected by CFC, in the absence of an LPR to HCMV, in the great majority or the totality (according to different intervals) of samples collected from both pregnant and nonpregnant individuals during follow-up; and (3) LPR to HCMV was significantly (P<.001) lowered or delayed in transmitter mothers, compared with that in nontransmitter mothers.Pregnancy does not influence the HCMV-specific immune response. A dissociation between CFC response and LPR is commonly observed in patients with primary infections, and ad hoc studies aimed at understanding the mechanism(s) of the reduced LPR in transmitter mothers are warranted.