Vitamin D insufficiency as a risk factor for reproductive losses in miscarriage.

OBJECTIVE

To study the relationship between vitamin D deficiency, VDR gene polymorphism rs10735810 (A > G), and a missed abortion in the first trimester of gestation; to determine the predictors of its risk.

RESEARCH METHODS

178 women aged between 18 and 41 were surveyed. The main group consisted of patients with miscarriage ( = 101), verified at the hospital stage (O02.0; O02.1), which were stratified by I group ( = 58, patients with the first miscarriage) and II groups ( = 43, patients with repeated miscarriage). The control group ( = 77) consisted of women with a successful pregnancy (Z34.0), which subsequently ended in delivery at term with a live fetus. Patients were surveyed and data was extracted from primary medical records. The level of 25(OH)D in the blood serum was investigated by mass spectrometry ( = 99). Genotyping for the vitamin D receptor gene polymorphism rs10735810 (VDR A > G) was performed for 177 patients. Statistical data analysis was performed Statistica 10 and SAS JMP 11 application packages, using single-factor prediction for quantitative and binary factors, ROC analysis, and CHAID decision tree construction.

RESULTS OF THE STUDY

WE found that patients with miscarriage in the first trimester of gestation ( = 60) more frequently than those in the control group ( = 39) had vitamin D insufficiency (93.3% versus 76.9%,  = .0183) including its deficiency, occurring at 25(OH)D of blood <20 ng/ml (71.7% versus 51.3%,  = .0392). This pattern was found in patients with the first miscarriage, where significant differences in the frequency of vitamin D deficiency were also detected in comparison with the control group (80.0% versus 51.3%,  = .0026). No direct correlation was found between the frequency of miscarriages in the first trimester and the variant of the polymorphism of the vitamin D receptor gene (VDR A > G [rs10735810]); the GG genotype in patients with repeated miscarriages was even less frequent compared to the control group (14.0% versus 23.7%,  = .3344). However, the decision tree has identified four risk classes and has determined that the highest risk of missed abortion in the cohort studied is formed by three predicates: smoking, serum level 25(OH) < 6.5 ng/ml and VDR AA and GG genotypes.

CONCLUSION

The data obtained show that vitamin D insufficiency plays a pathogenetically significant role in early reproductive losses associated with miscarriages, both first and recurrent.