Pregnancy complications and birth outcomes
Among medically recorded pregnancy complications the incidences of threatened abortion (OR: 1.3, 95% CI: 1.2-1.5), threatened preterm birth (OR: 1.4, 95% CI: 1.1-1.7) and anaemia (OR: 1.4, 95% CI: 1.3-1.6) were higher in the mothers of cases than in the mothers of matched controls. On the contrary, the risk of gestational diabetes was lower in the group of viral infections as compared to control mothers (OR: 0.4, 95% CI: 0.23-0.9). Detailed data are shown in Table 2. In the case of pregnancy complications, no differences have been found between the specific virus groups and the viral infection group in general. The only exception was a significantly higher risk of preeclampsia in the influenza group as compared to control mothers (OR: 1.3, 95% CI: 1.0-1.8, p<0.05).
Data on pregnancy outcome measures are presented in Table 3. Events during the 1st trimester may play a pivotal role in the proceedings of the whole pregnancy, as it was mentioned before. Therefore, pregnancy outcome results with a history of a viral infection during the first three months are also given. No significant differences have been detected in foetal birth weight or the prevalence of IUGR between the infected and the control groups. Preterm birth measures (birth before the completed 37th week or birth weight under 2,500 grams) also did not differ significantly between the two study groups. The only significant difference was the somewhat longer gestational age detected among infected mothers as compared to the control group (39.4±2.0 vs. 39.3±1.9 weeks). All pregnancy outcome results in the group of 1st trimester virus infection were congruent with results in the complete infected group. Among specific viral infections a significantly lower birth weight (2985.7±585.9 vs. 3297.4±521.0, p<0.05) and shorter gestational age (38.1±1.4 vs. 39.3±1.9, p<0.05) have been found in the case of mothers with hepatitis B as compared to the control group. None of the other pathogens resulted in specific alterations in pregnancy complications or birth outcomes different from virus infections in general.