## 3 Results
### Single Locus Associations  
All 310 samples were successfully genotyped, and the allele frequencies of the six genetic variants showed no deviation from the Hardy-Weinberg Equilibrium (HWE) in the control group (rs2071010, \(\chi^{2}\) = 0.006, \(p\) = 0.937; rs630074 \(\chi^{2}\) = 0.099, \(p\) = 0.951; rs61886492, \(\chi^{2}\) = 0.182, \(p\) = 0.912; rs11545078, \(\chi^{2}\) = 0.991, \(p\) = 0.609; rs3758149, \(\chi^{2}\) = 2.312, \(p\) = 0.314; rs1051266, \(\chi^{2}\) = 2.125, \(p\) = 0.345). The allele frequencies of the tested genetic variants were compared between groups of women with fetal demise and the controls and are presented in Table 4. In the IUFD group, a statistically significant increase in the frequency of \(A\) alleles of the rs61886492 variant of the \(FOLH1\) gene was observed compared to the controls (0.100 vs. 0.037, \(p\) = 0.011). In women who were carriers of the \(A\) allele, the risk of IUFD was 2.8 times higher compared to the control group (OR = 2.851; 95% CI: 1.227-6.624). No significant association was observed in the allelic frequencies in women with RM relative to controls. However, the distribution of the \(A\) allele of \(FOLR1\) rs2071010 was more frequent in women with RM than the controls (0.059 vs. 0.029, \(p\) = 0.115, OR = 2.090; 95% CI: 0.818-5.339). \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Parameter**} & **Controls** & **IUFD** & **RM** \\  & **(n = 120)** & **(n = 80)** & **(n = 110)** & \(p\)**-Value** \\ \hline Age (years) & 31.38 \(\pm\) 3.59 & 30.49 \(\pm\) 4.50 & 32.86 \(\pm\) 4.76 & \textless{}0.001 \\ \hline SBP (mmHg) & 100.0 [95.0; 110.0] & 107.50 [100.0; 120.0] & 110.0 [100.0; 120.0] & \textless{}0.001 \\ \hline DBP (mmHg) & 62.5 [60.0; 70.0] & 60.0 [60.0; 70.0] & 70.00 [60.0; 80.0] & 0.003 \\ \hline Height (cm) & 166.93 \(\pm\) 5.78 & 166.34 \(\pm\) 8.28 & 166.94 \(\pm\) 5.64 & 0.792 \\ \hline Weight (kg) & 57.86 \(\pm\) 6.67 & 62.31 \(\pm\) 9.92 & 65.74 \(\pm\) 12.41 & \textless{}0.001 \\ \hline BMI (kg/m\({}^{2}\)) & 20.72 \(\pm\) 1.75 & 22.55 \(\pm\) 3.57 & 23.53 \(\pm\) 3.98 & \textless{}0.001 \\ \hline Gestational age (weeks) & 39 [38; 40] & 29.5 [26; 34] & 14.5 [6; 18] & \textless{}0.001 \\ \hline Newborn weight (g) & 3483.75 \(\pm\) 399.83 & 1350.50 \(\pm\) 316.45 & - & \textless{}0.001 \\ \hline Placenta weight (g) & 605 [50; 70] & 412 [240; 560] & - & \textless{}0.001 \\ \hline Number of pregnancies & 2.0 [2.0; 3.0] & 2.0 [1.0; 3.0] & 4.0 [3.0; 5.0] & \textless{}0.001 \\ \hline childless women & 0 (0.00) & 59 (73.75) & 74 (67.27) & \textless{}0.001 \\ healthy newborn: & & & & \\ one & 0 (0.00) & 18 (22.50) & 30 (27.27) & \textless{}0.001 \\ \(\geq\)two & 120 (100.0) & 3 (3.75) & 6 (5.45) & \textless{}0.001 \\ \(\geq\)three & 0 (0.00) & 72 (90.00) & 0 (0.00) & \textless{}0.001 \\ miscarriages & & & & \\ one & 0 (0.00) & 20 (25.00) & 0 (0.00) & \textless{}0.001 \\ two & 0 (0.00) & 13 (16.25) & 0 (0.00) & \textless{}0.001 \\ \(\geq\)three & 0 (0.00) & 4 (5.00) & 110 (100.00) & \\ \hline Mean \(\pm\) SD, median [Q1; Q3]. & & & & \\ \end{tabular}
\end{table} 
Table 3: The clinical characteristic of the study groups (n = 310). The association between selected SNVs related to folate uptake and distribution in fetal demise groups and controls was analyzed using multiple logistic regression and the results are presented in Table 5. For _FOLR1_ rs630074, a statistically significant increase in the risk of IUFD was found for carriers of the CC genotype compared to the _TT_ and _TC_ genotypes in the recessive model (OR = 2.03, 95%CI: 1.06-3.90, \(p\) = 0.033, AIC = 268.7). The most interesting observations concerned the variant _FOLH1_ rs61886492. A statistically significant increase in the risk of IUFD was found in co-dominant (\(p\) = 0.030, AIC = 268.5), dominant (OR = 2.62, 95%CI: 1.07-6.38, \(p\) = 0.032, AIC = 268.6) and log-additive models (OR = 2.64, 95%CI: 1.15-6.06 \(p\) = 0.030, AIC = 267.5).