The Effect Of Different Folic Acid Supplementation Regimens On IVF/ICSI Outcomes In Infertile Women With MTHFR C677T TT Genotype

Background5,10-methylenetetrahydrofolate reductase(MTHFR)is a key enzyme in the folate metabolic pathway and plays an important role in vivo reactions by participating in folate and homocysteine(Hcy)metabolism.Mutation at site 677 of the MTHFR coding gene resulted in decreased enzyme activity.There are three genotypes of MTHFR C677 T : CC,CT and TT,corresponding enzyme activity was 100%,65% and 30%.Decreased enzyme activity can cause Hcy accumulation and low folate levels in the body.MTHFR C677 T polymorphisms and its associated increase in Hcy and decrease in folic acid are associated with increased risk of cardiovascular disease,neurological and psychiatric disorders,diabetes,and cancer.It also affects oocyte maturation and embryo quality,sperm quality,and are associated with recurrent miscarriage,pregnancy complications,and birth defects.Folic acid plays an important role in oocyte quality,oocyte maturation,embryo implantation,normal pregnancy and prevention of birth defects.Maternal folate deficiency is associated with an increased risk of fetal birth defects and an increased risk of fetal malformations,fetal growth restriction,preterm delivery,and certain placental disorders.Folic acid supplementation in women during pregnancy and early pregnancy significantly reduces the incidence of neural tube defects,congenital heart disease,and cleft lip and palate.Higher folic acid supplementation has better embryo implantation rates,clinical pregnancy rates,live birth rates,and a positive correlation between folic acid levels and fertilization rates.However,excessive maternal folic acid may cause increased incidence of gestational diabetes,offspring susceptibility to insulin resistance,obesity,and reduced DNA methylation levels in cord blood.Folic acid supplementation of at least 0.4 mg daily is recommended for the prevention of birth defects in women preparing for pregnancy.For women with MTHFR gene polymorphisms,it is recommended to increase the dose of folic acid supplementation or extend the duration of folic acid supplementation according to individualization as appropriate.The effect of different folic acid supplementation doses or supplementation regimens on the outcome of infertile women with MTHFR C677 T TT type who undergo assisted reproduction for pregnancy has not been well studied.Therefore,in this study,we first investigated the relationship between genetic polymorphisms,assessment indexes of folic acid and IVF/ICSI outcomes by testing MTHFR C677 T genotype,serum Hcy,serum folate,and red blood cell folate in the infertility population attending our hospital.Then,the effects of different folic acid supplementation regimens on IVF/ICSI outcomes in infertile women with MTHFR C677 T TT type were further investigated.Research ContentsPart I.Exploration of the relationship between MTHFR C677 T genotype and serum Hcy and IVF/ICSI outcomesObjectiveTo explore the relationship between serum Hcy,IVF/ICSI outcomes in patients with three genotypes of MTHFR C677 T.Materials and MethodsA total of 2376 patients undergoing IVF/ICSI assisted conception at the Department of Reproductive Health and Infertility,Guangdong Maternal and Child Health Hospital from January 2019 to December 2022 were retrospectively analyzed and divided into three groups with MTHFR C677 T genotype: CC(1145 patients),CT(985 patients)and TT(246 patients).The association of MTHFR C677 T genotype with serum Hcy and their IVF/ICSI outcomes was analyzed by Bonferroni/Kruskal-Wallis test and post hoc comparison and chi-square test.Results1..Serum Hcy was significantly higher in TT patients(10.41 ± 5.45 umol/L)than in CC(8.42 ± 1.92 umol/L)and CT(8.56 ± 2.18 umol/L)(P < 0.05),and there was no statistical difference between serum Hcy in CC and CT patients(P > 0.05).2.The number of high-quality blastocysts was significantly lower in TT patients than in CC and CT patients(P < 0.05),and the number of high-quality blastocysts obtained in CC patients compared with CT patients was not statistically significant(P > 0.05);the blastocyst formation rate and high-quality blastocyst rate obtained in the three genotype groups were CC type > CT type > TT type(P < 0.05).Conclusion1.The serum Hcy of patients with MTHFR C677 T TT genotype was significantly higher than that of CC and CT genotypes.2.The number of quality blastocysts obtained by IVF/ICSI in MTHFR C677 T TT genotype infertility patients was significantly lower than that of CC and CT patients.3.In patients with MTHFR C677 T genotype undergoing IVF/ICSI,the blastocyst formation rate and high quality blastocyst rate were CC type > CT type > TT type.Part II Exploration of the relationship between folic acid assessment index and IVF/ICSI outcomesObjectiveTo explore the relationship between erythrocyte folate,serum folate and Hcy levels in infertile women and their first IVF/ICSI outcomes,and to understand their predictive value for IVF/ICSI outcomes.Data and MethodsThe data of 205 infertile women who underwent IVF/ICSI assisted pregnancy at the Department of Reproductive Health and Infertility,Guangdong Maternal and Child Health Hospital from March 2022 to December 2022 and had their erythrocyte folate,serum folate and serum Hcy levels tested within 3 months from the time of egg retrieval were retrospectively analyzed.The erythrocyte folate levels were divided into four groups based on interquartile spacing,Q1(103.5 ~ 256.8 ng/ml),Q2(257.7 ~ 332.7 ng/ml),Q3(334.4~ 434.6 ng/ml)and Q4(442.3 ~ 1192.4 ng/ml),and the Bonferroni/Kruskal-Wallis test and post hoc comparisons,chi-square test and correlation analysis were applied to compare the relationship between erythrocyte folate levels in infertile women and their first IVF/ICSI outcomes.Results1.erythrocyte folate levels were positively correlated with serum folate levels(ρ =0.726,P < 0.05);erythrocyte folate levels were negatively correlated with serum Hcy levels(ρ = 0.191,P < 0.05);serum folate levels were negatively correlated with serum Hcy levels(ρ = 0.177,P < 0.05).2.The fertilization rate of 2PN obtained by IVF and ICSI in patients in group Q1(IVF 55.2%,ICSI 70.3%)was significantly lower than that obtained by patients in groups Q2(IVF 68.10%,ICSI 82.7%),Q3(IVF 66.7%,ICSI 87.7%)and Q4(IVF 67.1%,ICSI84.1%)fertilization rates(P < 0.05).Conclusions:1.erythrocyte folate levels were positively correlated with serum folate levels;serum Hcy levels were negatively correlated with erythrocyte folate and serum folate levels.2.2PN fertilization rate was significantly decreased in infertile women with erythrocyte folate levels < 256.8 ng/ml.Part III The effect of different folic acid supplementation regimens on IVF/ICSI outcomes in infertile women with MTHFR C677 T TT genotypeObjectiveTo investigate IVF/ICSI outcomes between three groups of MTHFR C677 T TT infertile women supplemented with synthetic folic acid 0.4 mg/day,0.8 mg/day and supplemented with active folic acid 400 μg/day.Materials and MethodsFolic acid supplementation and first IVF/ICSI outcomes were retrospectively analyzed in a total of 217 infertile women with MTHFR C677 T TT attending the Department of Reproductive Health and Infertility of Guangdong Maternal and Child Health Hospital from January 2019 to December 2022.The 217 patients were divided into group A(supplementation with synthetic folic acid 0.4 mg/day),group B(supplementation with synthetic folic acid 0.8 mg/day)and group C(supplementation with active folic acid400 μg/day),and folic acid supplementation for at least 1 month before egg retrieval in all three groups.The quality of IVF/ICSI assisted pregnancy embryos and pregnancy outcomes in the three groups were compared by Kruskal-Wallis test and post hoc comparisons,ANOVA and chi-square test.Results1.Timing of folic acid supplementation in groups A,B and C.There was a statistical difference in 2PN fertilization rate(P < 0.05).Duration of folic acid supplementation among the three groups: group A > group B > group C(P < 0.05);2PN fertilization rate was significantly lower in group A compared with groups B and C(P < 0.05),and there was no statistical difference in 2PN fertilization rate between groups B and C(P > 0.05).2.There was no statistical difference in the cumulative clinical pregnancy rate among patients in groups A,B and C.The cumulative clinical pregnancy rate in groups B and C showed an increasing trend compared with group A(P > 0.05),and there was no statistical difference in the biochemical pregnancy rate among the three groups(P > 0.05).Conclusion1.The fertilization rate of 2PN obtained by supplementation with synthetic folic acid0.4 mg was significantly lower than that of women supplemented with synthetic folic acid0.8 mg and active folic acid 400 μg at the time of folic acid supplementation as CC type >CT type > TT type.2.The cumulative clinical pregnancy rate obtained with synthetic folic acid supplementation 0.8 mg and active folic acid 400 μg was higher than that obtained with synthetic folic acid supplementation 0.4 mg when the duration of folic acid supplementation was CC type > CT type > TT type.