**3. Results**

### *3.1. Baseline Characteristics*

Table 1 describes the characteristics of participants in this study (*n* = 149), including vitamin supplementation in the first trimester and neonatal and maternal outcomes. The mean age was 34.7 ± 5.2 years old, and the mean pregestational BMI was 26.4 ± 5.50 kg/m2; the average weight gain at final of pregnancy was 11.6 ± 5.84 kg. Spontaneous gestation was observed with a higher frequency than assisted. Delivery was spontaneous in the majority of patients. Regarding maternal complications during gestation, 62.4% had GDM, 2.0% GHT, and 3.4% preeclampsia. Regarding neonatal outcomes, the mean birth weight was 3.18 ± 0.57 kg, 7.4% were PTB, and 8.8% were admitted to intensive care.

**Table 1.** Characteristics of the participants in this study.




Data show mean ± standard deviation or frequency (%). *N*, number; BMI, body mass index; GDM, gestational diabetes mellitus; GHT, gestational hypertension; PTB, preterm birth; ICU, intensive care unit; SGA, small for gestational age; AGA, appropriate for gestational age; LGA, large for gestational age.

All women received folic acid supplementation in the first trimester of pregnancy; 81.2% received a multivitamin complex that included folic acid, iodine, and B12; 13.4% received folic acid plus iodine; and 5.4% just folic acid. In addition to the supplementation with folic acid or multivitamin complex, 55.0% of women were prescribed iron supplementation.

#### *3.2. Distribution of SNP Genotypes of Genes Related to Folate and Cobalamin Metabolism and Transport in the Study Population*

The distribution of genotypes detected in women from the CHUS cohort was similar to the population distribution reported in Europe (Figure 1). It is important to highlight that 61% of the women analysed in this study carried risk alleles in the MTHFR gene, approximately 72% of women in this study carried risk alleles in the SCL19A1 gene, and risk alleles were detected in the CUBN gene in 47% of these women, while the majority of this population carried the reference allele for the MTR gene (99%).

### *3.3. Association between SNP Genotypes and Pregnancy Outcomes*

The association between maternal SNP and neonatal and maternal outcomes is shown in Table 2. Although only 1% of women were risk genotype carriers of *MTR*, and 75% of women in this study carried risk alleles in the *SCL19A1* gene, statistically significant associations were not found between the polymorphisms analysed of these genes, nor in *CUBN* and maternal or neonatal outcomes.

In women with the *MTHFR* risk allele, there was a statistically significant higher frequency of assisted fertilization (lower frequency of spontaneous gestation). In addition, there was a higher frequency of preeclampsia and PTB in women with variation in the genotype of *MTHFR*.

When the cohort was analysed according to complications in the mother's health, neonate's health, or delivery, no association was found between genotypes and complications except for *CUBN* (rs1801222), which showed a lower frequency of complications during delivery associated with the risk allele (white bars, *p* = 0.024; Figure 2).

**Figure 1.** Prevalence of SNP genotypes of genes related to folate and cobalamin metabolism and transport in the study population (CHUS), compared with European population (EU). AA, adenineadenine genotype; AG, adenine-guanine genotype; GG, guanine-guanine genotype; TT, thyminethymine genotype; TG, thymine-guanine genotype; CC, cytosine-cytosine genotype; TC, thyminecytosine genotype; MTHFR, methylenetetrahydrofolate reductase; SLC10A1, reduced folate carrier (RFC1); MTR, methionine synthase; CUBN, cubilin.

#### **Figure 2.** Association between complications in health of the mother, that of the neonate, or during delivery and SNP genotypes of genes related to folate and cobalamin metabolism and transport in the study population. (\*) indicates statistically significant differences in delivery complications (white bars) between both groups of genotypes (AA vs. AG/GG). AA, adenine-adenine genotype; AG, adenine-guanine genotype; GG, guanine-guanine genotype; TT, thymine-thymine genotype; TG, thymine-guanine genotype; CC, cytosine-cytosine geno-type; TC, thymine-cytosine genotype; MTHFR, methylenetetrahydrofolate reductase; SLC10A1, reduced folate carrier (RFC1); MTR, methionine synthase; CUBN, cubilin.
