General characteristics of the participants
Socio-demographic data of cases and controls are presented in Table 1.
Maternal age was slightly higher in the control group as compared to
infected mothers (26.2±5.1 vs. 25.8±4.7 years). The distribution of
maternal employment status indicated a higher socioeconomic status of
case mothers. The proportion of managerial mothers was 26.1% (N=585) in
the group of cases and 19.2% (N=10,533) in the control group, while
that of unskilled mothers were 1.9% (N=44) in the infected group, and
3.6% (N=1,967) in controls. No significant differences were found in
birth order (primiparous women among cases: 1,276 (57.0%) vs. 48,801
(54.9%) in the control group). A highly significant difference between
the two study groups has been found in maternal smoking. The proportion
of smoker mothers was 15.9% in the group of viral infections while
8.7% in the control group.