The average frequencies of MN in samples from 29 patients, before and after the end of therapy, and who have been divided into four groups, depending on the type of applied therapy, are presented in Table 1. Gestormone, Progesterone depo and Gravibinone increased MN frequency when compared to average values before therapy, with probability p<0.05, while Utrogestane also increased the frequency, but without statistical significance (p<0.1).

The summarized results of ANOVA (Table 2) for MN frequency show that between group and within group variances, statistically significant difference exists (F = 8.63; p = 0.005). The variability in MN frequency could be attributed to the gestagen therapy, having in mind differences in dosage depending on their clinical state, and the possibility of differences in sensitivity to gestagens. Different life conditions, such as working and life environments, diet, former therapeutic treatment, and some habits, can influence the MN variability. For example, vegetarian diet and alcohol consumption can increase the MN frequency induced by smoking [11-13], while drinking tea tended to decrease MN frequency [13].

By analysis of variance, we have determined the participation of both genetic factors and gestagen therapy, in genesis of phenotypic variability. By comparison of variances of patients before and after gestagen therapy, we concluded that the influence of gestagen therapy (79.2%) on variability in MN frequency is greater than influences of genetic factors (20.8%).

The more detailed ANOVA results for MN frequency in investigated samples, in relation to type of applied therapy, are presented in Table 3. In all investigated groups, between group variance (S²_BG) is greater in relation to within group variance (S²_WG), and that is attributed to the influence of applied therapy. By comparison of between group and within group variance, a statistically significant difference was found in the therapy with Progesterone depo (p = 0.006), while this was not the case in the other therapies, and that can be explained by the relatively small number of persons to whom the therapy was applied (Table 4). The greatest within group variance (S²_WG) was observed in therapy by Progesterone depo preparations, which can be explained by the individual sensitivity of female patients on the prescribed therapy.

The smallest between and within group variance in MN frequency was observed in patients who has received Gestormone (S²_BG = 60.5; S²_WG = 11.8) and Gravibinone (S²_BG = 62.5; S²_WG = 23.1), that can be explained by the lowest applied average doses of therapy.

We conclude that therapy with Gestormone, Progesterone depo, Gravibinone and Utrogestane, that has been applied in the first 3 months of pregnancy, significantly increases the frequency and variability of MN in peripheral blood lymphocytes of the studied female patients.