Homocysteine Is Lower in the Third Trimester of Pregnancy in Women with Enhanced Folate Status from Continued Folic Acid Supplementation

Supplementation with Folic Acid or 5-Methyltetrahydrofolate and Prevention of Neural Tube Defects: An Evidence-Based Narrative Review

Background: Folic acid (FA), which in its chemical form is pteroylglutamic acid, is the fully oxidised, water-soluble, monoglutamic form of vitamin B9. This compound is part of the folate group but with higher bioavailability, and it is found in vitamin supplements and fortified foods and drugs. Folate metabolism is complex and associated with various metabolic pathways, all of which confer protection on the cell and allow its survival. Methods: We conducted a non-systematic search of articles published in English and Spanish including controlled trials, cohort studies, systematic re-views, and meta-analyses were included, as well as key studies in animal models related to pharmacokinetic studies. Search terms encompassed: "folic acid", "folates", "5-metyltetrahydrofolate", "5-MTHF", "neural tube defects", "supplementation", "fortification", AND "homocysteine" Results: A crucial role demonstrated for FA is to help prevent neural tube defects (NTDs). However, more studies are definitely still needed to establish 5-MTHF as a safe and effective therapeutic approach comparable with FA. Moreover, there is a lack of clinical studies that evaluate the efficacy of 5-MTHF supplementation in the prevention of NTDs. The present evidence-based narrative review discusses differences between FA and 5-MTHF in terms of structure, metabolism, bioavailability, clinical efficacy, and safety. Conclusions: Despite the potential value of 5-MTHF as an alternative to FA, clinical studies would be urgently needed to support the efficacy, dosage, timing, and/or safety of its use as a supplement.

The effect of methionine and folic acid administered in ovo on the blood biochemical parameters of chickens (Gallus gallus domesticus)

Methionine is one of the most frequently supplemented amino acids in raising of poultry. However, an overdose of methionine can cause hyperhomocysteinemia. Folic acid, taking part in the process of homocysteine remethylation, is a factor affecting the reduction of the concentration of this amino acid. The study was carried out in 2 stages. The experiment of step I was to investigate the effect of methionine and/or folic acid administration in ovo in the early stage of embryogenesis (E4), and the experiment of the second stage - in the late stage of embryogenesis (E17) on the following biochemical parameters of chicken blood: glucose concentration in whole blood and concentration of homocysteine and uric acid in plasma of domestic chickens (Gallus gallus domesticus). Our results confirm that methionine supplementation may increase the concentration of uric acid and homocysteine. Moreover, we demonstrated that folic acid administered during embryogenesis decreased homocysteine concentration, also in groups simultaneously supplemented with methionine, especially in the initial stage of postnatal life of the bird.

Trimester-specific reference intervals of serum homocysteine levels for pregnant women: a longitudinal study in China

OBJECTIVE

To investigate the physiological changes of serum homocysteine (Hcy) levels and to establish trimester-specific reference intervals of serum Hcy levels for Chinese pregnant women.

METHOD

According to the guideline of the Clinical and Laboratory Standards Institute (CLSI) C28-A3 document, 476 healthy women were recruited in West China Second University Hospital, Sichuan University from January 2021 to October 2021. Among them, 120 were non-pregnant, 118 were in the first trimester, 120 were in the second and 118 were in the third trimester of gestation. The enzymatic cycling method was performed to detect serum Hcy levels. Non-parametric percentiles (2.5th percentile and 97.5th percentile) were calculated to establish the reference intervals for non-pregnant women and pregnant women in different trimester of gestation.

RESULTS

There was a significant statistical difference for serum Hcy levels between non-pregnant women and pregnant women (p < 0.05), and serum Hcy levels in the first, second, and third trimesters of gestation were statistically different (p < 0.05). The trimester-specific reference intervals of serum Hcy levels were 4.35 ∼ 10.16 μmol/L, 3.38 ∼ 8.60 μmol/L, and 3.75 ∼ 11.17 μmol/L for pregnant women in the first, second, and third trimester of gestation, respectively.

CONCLUSIONS

Compared to non-pregnant women, serum Hcy levels physiologically decreased after pregnancy, and the physiological changes in serum Hcy levels during pregnancy were also found. Establishing trimester-specific reference intervals of serum Hcy levels for pregnant women was valuable for clinical practice.

Folic acid supplementation is associated with size at birth in the Screening for Pregnancy Endpoints (SCOPE) international prospective cohort study

BACKGROUND

Small-for-gestational-age (SGA) is a significant cause of morbidity and mortality, and there are currently few preventive strategies.

AIM

The aim of this study was to investigate the relationship between maternal folic acid supplement (FAS) use pre-conception through to the second trimester, and small-for-gestational age (SGA) and birth size parameters.

STUDY DESIGN

Women were recruited as part of the Screening for Pregnancy Endpoints (SCOPE) international prospective multi-centre cohort study: New Zealand, Australia, United Kingdom and Ireland. Information on FAS use pre-conception, during the first trimester and at 15 ± 1 weeks' gestation was collected via interview administered questionnaire. Participants were followed through to delivery. Pregnancy outcome data and birth measurements were collected within 72 h of birth. Multivariable regression analysis was used to investigate relationships between FAS and outcomes, adjusting for maternal sociodemographic and lifestyle factors.

SUBJECTS

Nulliparous women with singleton pregnancies.

OUTCOME MEASURES

SGA (<10th customised birthweight centile).

RESULTS

5606 women were included. SGA prevalence was 11.3%. Pre-conception FAS was associated with a significantly lower risk of SGA: aOR = 0.82 (95% CI: 0.67-01.00 p = 0.047). Although the association between FAS at 15 weeks' gestation and SGA did not reach significance, FAS at 15 weeks was associated with a significantly higher customised birthweight centile (β 2.56 (95% CI: 0.87-4.26; p = 0.003). There was no significant effect of FAS on large-for-gestational-age births or head circumference.

CONCLUSIONS

In this international cohort, FAS was positively associated with fetal growth, without increasing risks associated with LGA. Further studies are required to confirm whether continuing FAS beyond the first trimester might lower the risk of SGA.

Association of Cystathionine β-Synthase Gene Polymorphisms With Preeclampsia

Preeclampsia (PE) is a pregnancy disorder that increases maternal and fetal morbidity and mortality worldwide. High plasma levels of homocysteine (Hcy) are a risk factor for several cardiovascular diseases. Cystathionine β-synthase (CBS) plays an important role in Hcy homeostasis catalyzing the irreversible degradation of Hcy to cystathionine, protecting the endothelium from injury caused by hypoxia. Several mutations and polymorphisms may alter the expression of the CBS gene, resulting in variable levels of Hcy. The purpose of this study was to investigate the association of CBS gene polymorphisms with PE in Mexican women. A case–control study consisting of 129 pregnant women with PE (37 severe and 92 mild) and 173 women with uncomplicated pregnancies was performed. Polymorphisms, such as G797A, C785T, T833C, G919A, T959C, C1105T, and 844ins68 base pair, in the CBS gene were genotyped. The polymorphism G797A was monomorphic in cases with the presence of only G797A-G allele. Allele C785T-T and genotype C785T-C/T were associated with susceptibility in severe and mild PE. Alleles G797A-G and T959C-T were associated with susceptibility only in severe PE. Haplotype TGTWGTC was of susceptibility for severe PE and of protection for mild PE. Haplotypes CGTWGCC and CATWGTC seem to be protective for severe PE, but the latter is related to susceptibility in mild PE. The results suggest that C785T, G797A, and T959C mutations are contributing in different ways in severe and mild PE in our population and could be count as another related factor for this disease.

Maternal Continuing Folic Acid Supplementation after the First Trimester of Pregnancy Increased the Risk of Large-for-Gestational-Age Birth: A Population-Based Birth Cohort Study

Supplementation with folic acid (FA) was proven to prevent neural tube defects (NTDs) and was recommended worldwide before and during early pregnancy. However, much less is known regarding the role of FA after the 12th gestational week (GW). This study aimed to investigate the related effects of continued FA supplementation after the first trimester of pregnancy on fetal growth. The study subjects came from the Ma’anshan-Anhui Birth Cohort Study (MABC) that recruited 3474 pregnant women from the city of Ma’anshan in Anhui Province in China during the period of May 2013 to September 2014. The information on use of vitamin and mineral supplements was recorded in different periods (the first/second/third trimester of pregnancy). Small-for-gestational-age (SGA) births were live-born infants that were <10th percentile of birth weight, and large-for-gestational-age (LGA) births were live-born infants that were ≥90th percentile of birth weight according to nomograms based on gender and gestational age from the latest standards. We used multivariable logistic regression to evaluate the effects of FA supplement consumption in the second/third trimester of pregnancy on the risk of LGA and SGA. In addition, propensity score analysis was also performed to examine the effects. In this prospective birth cohort study conducted in Chinese women who had taken FA in the first trimester of pregnancy, we found that continued FA supplementation with 400 micrograms/day in the second and third trimesters of pregnancy significantly increased the risk of LGA (RR = 1.98 (1.29, 3.04)). This relation was strong or monotonic after adjusting for maternal age, newborn’s gender, maternal pre-pregnancy BMI, maternal education level, smoking, alcohol consumption and calcium supplementation. We did not observe that continuing FA supplementation after the first trimester of pregnancy remarkably decreased the risk of SGA. The propensity score analysis showed similar results. To confirm these findings, additional investigations or trials with a large sample and the tracking of folate status throughout pregnancy are recommended.

The association of single nucleotide polymorphisms of the maternal cystathionine-β-synthase gene with early-onset preeclampsia

OBJECTIVES

Preeclampsia (PE) is a pregnancy complication, characterized by hypertension and proteinuria. The transsulfuration pathway may be involved in its pathophysiology, since homocysteine, cystathionine and cysteine are increased in PE. Cystathionine-β-synthase (CBS) is a key-enzyme in the pathway, converting homocysteine into cysteine via cystathionine. Another product of CBS is hydrogen sulfide (H2S), a vasodilatory, proangiogenic and cytoprotective gas that is thought to play a role in placental and vascular function during pregnancy. Since single nucleotide polymorphisms (SNPs) can affect CBS expression and/or function, we studied tag-SNPs in the CBS gene in PE patients.

STUDY DESIGN

Controls (n=75), early-onset (n=45), and late-onset PE (n=52) cases were genotyped for six tag-SNPs in the CBS gene; rs12329764, rs2851391, rs234713, rs234706, rs1789953, and rs11203172. Plasma homocysteine, cysteine and cystathionine were determined during pregnancy.

MAIN OUTCOME MEASURES

Early-onset PE, late-onset PE.

RESULTS

Women with the minor allele of rs11203172 have a reduced risk for early-onset PE. Compared to women without the minor allele, normotensive pregnant women with the minor allele of rs11203172 and rs234713 have lower cysteine levels. Women with the minor allele of rs1789953 have increased levels of cysteine and cystathionine, compared to women without.

CONCLUSION

The CBS tag-SNP rs11203172 is associated with a decreased risk for early-onset PE. Decreased cysteine concentrations in normotensive pregnant women carrying the minor allele of rs11203172, may be due to increased cysteine conversion to H2S by CBS. Higher H2S levels may positively affect placentation and vascular function during pregnancy and decrease their risk for PE.

Revisiting the role of first trimester homocysteine as an index of maternal and fetal outcome

Aim. To revisit the role of first trimester homocysteine levels with the maternal and fetal outcome. Methods. This was a cohort study comprising 100 antenatal women between 8 and 12 weeks of gestation. Serum homocysteine levels were checked after overnight fasting. Results. There were significantly elevated homocysteine levels among women with prior history of hypertensive disorders of pregnancy and prior second or third trimester pregnancy losses. There was no significant difference in homocysteine levels among women with previous gestational diabetes mellitus, preterm deliveries, or fetal malformations. Homocysteine levels were significantly elevated in those who developed hypertensive disorder of pregnancy, oligohydramnios, and meconium stained amniotic fluid, had a pregnancy loss, or delivered a low birth weight baby. There was no significant difference in homocysteine levels for those who developed gestational diabetes mellitus. Conclusions. Increased first trimester serum homocysteine is associated with history of pregnancy losses, hypertensive disorders of pregnancy, and preterm birth. This is also associated with hypertensive disorders of pregnancy, pregnancy loss, oligohydramnios, meconium stained amniotic fluid, and low birth weight in the current pregnancy. This trial is registered with ClinicalTrials.gov CTRI/2013/02/003441.

Low plasma vitamin B-12 is associated with a lower pregnancy-associated rise in plasma free choline in Canadian pregnant women and lower postnatal growth rates in their male infants

BACKGROUND

Choline needs are increased in pregnancy. Choline can be used as a source of methyl for homocysteine remethylation to methionine, but choline synthesis requires methyls from methionine. Vitamin B-12 deficiency increases choline use for homocysteine methylation.

OBJECTIVES

We investigated whether poor vitamin B-12 status occurs and contributes to low plasma choline and altered biomarkers of choline synthesis in pregnant women. With the use of a post hoc analysis, we addressed the association of maternal plasma vitamin B-12 status with postnatal growth rates in term infants.

DESIGN

Blood was analyzed for a prospective study of 264 and 220 pregnant women at 16 and 36 wk of gestation, respectively, and 88 nonpregnant women as a reference.

RESULTS

The proportion of women with a plasma total vitamin B-12 concentration <148 pmol/L (deficient) or 148-220 pmol/L (marginal) increased with pregnancy and pregnancy duration, which affected 3% and 9% of nonpregnant women, 10% and 21% of women at 16 wk of gestation, and 23% and 35% of women at 36 wk of gestation, respectively. Plasma free choline, betaine, and dimethylglycine were lower in women at 36 wk of gestation with a deficient or marginal compared with sufficient plasma total vitamin B-12 concentration (>220 pmol/L). Plasma total vitamin B-12 was positively associated with the increase in plasma free choline from midgestation to late gestation (P < 0.001). The postnatal growth rate to 9 mo was lower in infant boys of women classified as total vitamin B-12 deficient compared with sufficient.

CONCLUSION

This study shows that maternal vitamin B-12 status is related to choline status in late gestation in a folate-replete population and may be a determinant of infant growth even in the absence of undernutrition.

Is 5-methyltetrahydrofolate an alternative to folic acid for the prevention of neural tube defects?

Women have higher requirements for folate during pregnancy. An optimal folate status must be achieved before conception and in the first trimester when the neural tube closes. Low maternal folate status is causally related to neural tube defects (NTDs). Many NTDs can be prevented by increasing maternal folate intake in the preconceptional period. Dietary folate is protective, but recommending increasing folate intake is ineffective on a population level particularly during periods of high demands. This is because the recommendations are often not followed or because the bioavailability of food folate is variable. Supplemental folate [folic acid (FA) or 5-methyltetrahydrofolate (5-methylTHF)] can effectively increase folate concentrations to the level that is considered to be protective. FA is a synthetic compound that has no biological functions unless it is reduced to dihydrofolate and tetrahydrofolate. Unmetabolized FA appears in the circulation at doses of >200 μg. Individuals show wide variations in their ability to reduce FA. Carriers of certain polymorphisms in genes related to folate metabolism or absorption can better benefit from 5-methylTHF instead of FA. 5-MethylTHF [also known as (6S)-5-methylTHF] is the predominant natural form that is readily available for transport and metabolism. In contrast to FA, 5-methylTHF has no tolerable upper intake level and does not mask vitamin B12 deficiency. Supplementation of the natural form, 5-methylTHF, is a better alternative to supplementation of FA, especially in countries not applying a fortification program. Supplemental 5-methylTHF can effectively improve folate biomarkers in young women in early pregnancy in order to prevent NTDs.

Impact of continuing folic acid after the first trimester of pregnancy: findings of a randomized trial of Folic Acid Supplementation in the Second and Third Trimesters

BACKGROUND

Supplementation with folic acid (FA) is recommended worldwide before and during early pregnancy because of its proven effect in preventing neural tube defects, but the role of FA after the 12th gestational week (GW) is much less clear.

OBJECTIVE

We investigated maternal folate and homocysteine responses and related effects in the newborn that resulted from continued FA supplementation after the first trimester of pregnancy.

DESIGN

Pregnant women, aged 18-35 y, who were attending an antenatal clinic in Northern Ireland with singleton uncomplicated pregnancies and reported taking FA supplements in the first trimester, were randomly assigned at the start of trimester 2 to receive 400 μg FA/d or a placebo capsule.

RESULTS

A total of 119 women (60 women in the placebo group; 59 women in the treatment group) completed the trial. From GWs 14-36, mean (±SD) serum folate decreased (from 45.7 ± 21.3 to 19.5 ± 16.5 nmol/L; P < 0.001) in unsupplemented women, whereas plasma homocysteine increased (6.6 ± 2.3 to 7.6 ± 2.3 μmol/L; P < 0.001). However, FA supplementation prevented these changes and resulted in a significant increase in red blood cell folate concentrations from 1203 ± 639 to 1746 ± 683 nmol/L (P < 0.001; GWs 14-36). Cord blood folate was significantly higher in the FA group than in the placebo group (red blood cell concentrations of 1993 ± 862 and 1418 ± 557 nmol/L, respectively; P = 0.001).

CONCLUSIONS

Continued supplementation with 400 μg FA/d in trimesters 2 and 3 of pregnancy can increase maternal and cord blood folate status and prevent the increase in homocysteine concentration that otherwise occurs in late pregnancy. Whether these effects have benefits for pregnancy outcomes or early childhood requires additional study.

A prospective study of maternal fatty acids, micronutrients and homocysteine and their association with birth outcome

Our earlier studies both in animals and in humans have indicated that micronutrients (folic acid, vitamin B12) and long-chain polyunsaturated fatty acids, especially docosahexaenoic acid (DHA), are interlinked in the one-carbon cycle, which plays an important role in fetal 'programming' of adult diseases. The present study examines the levels of maternal and cord plasma fatty acids, maternal folate, vitamin B12 and homocysteine in healthy mothers at various time points during pregnancy and also examine an association between them. A longitudinal study of 106 normal pregnant women was carried out, and maternal blood was collected at three time points, viz., T1 = 16-20th week, T2 = 26-30th week and T3 = at delivery. Cord blood was collected at delivery. Fatty acids were estimated using a gas chromatograph. Levels of folate, vitamin B12 and homocysteine were estimated by the chemiluminescent microparticle immunoassay (CMIA) technology. Maternal plasma folate (P < 0.05), vitamin B12 (P < 0.01) and DHA (P < 0.05) levels were lowest, while maternal homocysteine levels were highest (P < 0.01) at T3. There was a negative association between maternal DHA and homocysteine at T2 (P < 0.05) and T3 (P < 0.01). There was a positive association between plasma DHA in maternal blood at T3 and cord blood. Furthermore, there was a positive association between maternal folate and vitamin B12 at T3 and baby weight, whereas maternal homocysteine at T1 were inversely associated with baby weight at delivery. Our study provides evidence for the associations of folic acid, vitamin B12, homocysteine with DHA and baby weight, suggesting that a balanced dietary supplementation of folate-vitamin B12-DHA during pregnancy may be beneficial.

First-trimester serum folate levels and subsequent risk of abortion and preterm birth among Japanese women with singleton pregnancies

OBJECTIVES

To determine whether a low serum folate level during the first trimester predicts subsequent late abortion, preterm birth, or fetal growth restriction (FGR).

STUDY DESIGN

A prospective cohort study involving 5,075 women whose serum folate levels were measured during the first trimester. The participants were informed of their serum folate levels.

RESULTS

The pregnancy duration, birthweight, rate of late abortion/preterm birth, and the rate of FGR did not differ significantly among the four groups classified according to folate status. The mean serum folate levels did not differ among quartiles classified according to the gestational week at the time of delivery. Nineteen of the 20 women with folate deficiency gave birth at term to infants with a birthweight of 3.132 ± 321 g; only one infant had FGR.

CONCLUSION

Low serum folate levels during the first trimester were not associated with the risk of late abortion, preterm birth, or FGR.

Maternal choline intake modulates maternal and fetal biomarkers of choline metabolism in humans

BACKGROUND

In 1998 choline Adequate Intakes of 425 and 450 mg/d were established for nonpregnant and pregnant women, respectively. However, to our knowledge, no dose-response studies have been conducted to evaluate the effects of pregnancy or maternal choline intake on biomarkers of choline metabolism.

OBJECTIVE

We sought to quantify the effects of pregnancy and maternal choline intake on maternal and fetal indicators of choline metabolism.

DESIGN

Healthy pregnant (n = 26; 27 wk gestation) and nonpregnant (n = 21) women were randomly assigned to receive 480 or 930 mg choline/d for 12 wk. Fasting blood samples and placental tissue and umbilical cord venous blood were collected and analyzed for choline and its metabolites.

RESULTS

Regardless of the choline intake, pregnant women had higher circulating concentrations of choline (30%; P < 0.001) but lower concentrations of betaine, dimethylglycine, sarcosine, and methionine (13-55%; P < 0.001). Obligatory losses of urinary choline and betaine in pregnant women were ∼2-4 times as high (P ≤ 0.02) as those in nonpregnant women. A higher choline intake yielded higher concentrations of choline, betaine, dimethylglycine, and sarcosine (12-46%; P ≤ 0.08) in both pregnant and nonpregnant women without affecting urinary choline excretion. The higher maternal choline intake also led to a doubling of dimethylglycine in cord plasma (P = 0.002).

CONCLUSION

These data suggest that an increment of 25 mg choline/d to meet the demands of pregnancy is insufficient and show that a higher maternal choline intake increases the use of choline as a methyl donor in both maternal and fetal compartments. This trial was registered at clinicaltrials.gov as NCT01127022.

Placental markers of folate-related metabolism in preeclampsia

The etiology and degree of clinical symptoms of preeclampsia depend on genotypic and phenotypic maternal and trophoblast factors, and elevated levels of plasma homocysteine (Hcy) are one of the pathogenetic factors of preeclampsia. To assess the impact of the folate-related metabolism, we characterized the indices of this metabolism in 40 samples from uncomplicated term placentas and 28 samples from preeclamptic pregnancies by quantifying the total content of folate, methionine (Met), Hcy and related cysteine, and glutathione (GSH) in compliance with the 677 C/T genotype of methylene tetrahydrofolate reductase (MTHFR). The prevalence ofMTHFRgenotypes was not significantly different between the two groups. The polymorphism ofMTHFRwas not unambiguously connected with the content of total placental Met, Hcy and related cysteine, and GSH either in uncomplicated or in complicated pregnancies. By contrast, the combination of the heterozygousMTHFRgenotype with folate deficiency in the samples from preeclamptic pregnancies was characterized by a statistically significant decrease in the Met content, a trend toward increased Hcy levels and a tight association between metabolically directly and indirectly related compounds, e.g. positive relation between Hcy versus cysteine and folate versus GSH and negative relation between folate versus Hcy and both Hcy and cysteine versus GSH. We demonstrated the expression of cystathionine-β-synthase (CBS) in human placenta at term by RT-PCR and western blot analysis, for the first time, and confirmed its catalytic activity and the accumulation of cysteine and CBS in placental explants cultivated in the presence of elevated Hcy concentrations. We suggest that disturbance in placental folate-related metabolism may be one of the pathogenetic factors in preeclampsia.

The effect of folic acid on ovine fetuses in utero during late gestation

To investigate whether folic acid would have toxic effects on fetal cardiac, hepatic, and renal functions, this was the first in utero fetal study testing acute effects of folic acid at the last third of gestation. Folic acid (5 mg/day) or 0.9% saline as the control was intragastricly administrated into pregnant ewes. Both maternal and fetal blood were analyzed for pH, PO(2), PCO(2), SO(2)%, hemoglobin, hematocrit, glucose, lactic acid, osmolality, Na(+), and K(+) concentrations. Maternal and fetal cardiovascular functions were assessed by examining cardiac enzymes and cardiovascular responses in vivo. Fetal hepatic and renal functions were examined by analysis of biochemistry index and renal excretion. Folic acid did not alter the blood values in both ewes and fetuses. Cardiac enzyme activities remained unchanged, and no alteration in cardiovascular responses was observed. Folic acid did not affect fetal urine volume, urine electrolytes, and osmolality. Enzyme activities related to hepatic and renal functions were not changed. In addition, maternal application of folic acid had no effect on maternal and fetal lipid profile. The results showed that folic acid used (5 mg/day) during the last third of gestation did not cause biochemical changes related to cardiac, hepatic, and renal functions in both maternal and fetal sheep, providing new information for use of folic acid during late pregnancy.

Women's compliance with current folic acid recommendations and achievement of optimal vitamin status for preventing neural tube defects

BACKGROUND

The timing of folic acid supplement usage is critical to preventing pregnancies affected by neural tube defects (NTDs) because the neural tube closes by Day 28 post-conception. We investigated compliance of pregnant women with current folic acid recommendations (400 µg/day from preconception to 12 weeks) in relation to achieving a folate status associated with lowest risk of NTDs.

METHODS

From a sample of 296 women with singleton uncomplicated pregnancies attending an antenatal clinic in Northern Ireland, those who reported taking folic acid in the first trimester (n = 226) were investigated. Samples were taken at 14 weeks gestation to measure serum concentrations of folate and vitamin B12 (related to folate and an independent predictor of NTD), and dietary B-vitamin intake and folic acid usage were investigated.

RESULTS

Although the majority of the overall sample (84%) reported taking folic acid supplements in the first trimester, only 19% had started before conception, as recommended. Multigravidae compared with primigravidae women were less likely to have followed the recommendations correctly (P= 0.001). At 14 weeks, red cell folate (considered a reliable biomarker of previous 3 months, covering time of neural tube closure) was correlated (r = 0.320, P < 0.001) with the reported duration of folic acid usage, and was lower (P< 0.0001) in women who started folic acid after conception.

CONCLUSIONS

Red cell folate concentrations in women not complying with recommendations were suboptimal in relation to NTD risk. The findings generally support the recent official recommendation to the Chief Medical Officer for mandatory fortification of food with folic acid in the UK.

The influence of folic acid supplementation on maternal and fetal bone turnover

The aim of our study was to investigate the relationship between maternal and fetal bone turnover markers and folic acid supplementation during pregnancy. In an observational study performed in Tehran University of Medical Sciences related hospitals, 113 healthy pregnant women with gestational age between 8 and 12 weeks and aged between 15 and 42 years were recruited and followed until delivery time. The participants were divided into two groups; women who took 1 mg of folic acid daily supplement from the beginning of the pregnancy until the end of the second trimester entered into group I and women who choose to continue their daily intake of folic acid until the delivery time entered into group II. The two groups were matched based on the maternal anthropometric data, energy, calcium and vitamin D intake. Following the delivery, venous blood samples were collected from mothers and umbilical cords of the neonates. Maternal and fetal serum concentrations of 25-hydroxy vitamin D3, PTH, osteocalcin (OC), crosslaps and maternal serum level of homocysteine, folate, soluble receptor activator of NF-kappaB ligand (sRANKL), osteoprotegerin (OPG), calcium, and phosphate were measured. Measured birth outcome parameters included weight, length, head circumference, appearance, and respiration. With regard to maternal assessment, the serum levels of OC and OPG and folate were significantly higher in group II compared to group I, while the serum levels of RANKL and homocysteine were significantly higher in group I. We did not find significant differences in serum levels of 25-OH vitamin D, PTH, crosslaps, calcium, or phosphate between the two groups. The neonates from mothers recruited in group II had higher (but not significantly) serum level of OC. We observed that the neonates born from mothers in group II had overall better birth outcome parameters and apgar scores compare to the neonates born from mothers in group I. Our results show that daily supplementation of folic acid during pregnancy could have a positive impact on the bone turnover markers in mothers and their newborns. This may suggest that both pregnant mothers and their fetuses could benefit from positive effects of folic acid taken during the whole period of pregnancy.

Homocysteine in pregnancy

The aim of this review is to evaluate the evidence for and against fasting plasma total homocysteine (tHcy) as a biomarker/risk factor of impaired reproductive function before and during pregnancy. Apart from nutritional and lifestyle factors, tHcy is also influenced by physiological factors specific to pregnancy such as hemodilution, increased glomerular filtration rate, and endocrinological changes. These lead to a considerable reduction under normal circumstances in tHcy by midpregnancy. Stimulating excess endogenous homocysteine production before and during pregnancy in animal experiments and adding exogenous homocysteine to cell cultures result in the impairment of reproductive and developmental processes from preconception throughout pregnancy and during subsequent development of the offspring. Different studies have confirmed that elevated tHcy is a risk factor for subfertility, congenital developmental defects, preeclampsia, and intrauterine growth retardation. There is conflicting evidence that elevated tHcy is a risk factor for miscarriage, gestational diabetes, premature rupture of the membranes, placental abruption, and offspring with Down syndrome. Prospective, sufficiently powered, studies from preconception/early pregnancy are required to determine whether tHcy is a risk factor for these pregnancy complications.

Homocysteine, red cell, and plasma folate concentrations and birth weight in Italian women: results from a prospective study

OBJECTIVE

A prospective cohort study conducted in Italy on homocysteine and red cell folate levels in pregnancy and pregnancy outcome.

METHODS

A cohort of pregnant women was identified in 21 Italian obstetric centers. Women were eligible at 8th-10th week of gestation. All women were followed up to delivery in order to collect information on pregnancy outcome and birth weight (BW).

RESULTS

Two hundred forty-four women were included in the analysis. In women not reporting current use of folate at study entry, the median homocysteine levels (micromol/l) were 7.9, 8.1, and 8.5 at the 8th-10th, 16th, and 22nd week of gestation, respectively; the median red cells folate levels (nmol/dl) were 3.9, 6.1, and 7.0. The mean BW tended to be lower in the 2nd and 3rd tertile of homocysteine levels in comparison with the 1st tertile (p<0.05 at the 8th-10th and 22nd week). The mean week of gestation at birth was higher in subjects in the 2nd and 3rd tertile of red cell folate at the 8th?10th and 16th week of gestation.

CONCLUSION

This study estimated homocysteine and plasma folate levels in Italian pregnant women and suggested that homocysteine level was associated with BW.

Homocysteine: biomarker or cause of adverse pregnancy outcome?

Total fasting plasma homocysteine (tHcy) is significantly reduced during early-mid normal pregnancy. Elevated tHcy during or outside of pregnancy has been associated with adverse pregnancy outcomes, affecting either the fetus or the evolution of the pregnancy. Examples of direct adverse effects on the fetus are neural tube defects, Down's syndrome, congenital heart defects and intrauterine growth retardation. Both fetal and maternal wellbeing can be affected by other adverse outcomes reported to be associated with elevated tHcy, such as recurrent spontaneous abortion, pre-eclampsia or placental vasculopathy. To date, endothelial activation of the placental vascularization system, apoptosis, toxicity and stimulation of uterine contractions have been proposed as possible modes of adverse action of homocysteine. The strength of the clinical evidence for a pathological role of elevated homocysteine in the evolution of pregnancy is examined in this review.

Effects of Folate and Vitamin B12 Deficiencies During Pregnancy on Fetal, Infant, and Child Development

The importance of folate in reproduction can be appreciated by considering that the existence of the vitamin was first suspected from efforts to explain a potentially fatal megaloblastic anemia in young pregnant women in India. Today, low maternal folate status during pregnancy and lactation remains a significant cause of maternal morbidity in some communities. The folate status of the neonate tends to be protected at the expense of maternal stores; nevertheless, there is mounting evidence that inadequate maternal folate status during pregnancy may lead to low infant birthweight, thereby conferring risk of developmental and long-term adverse health outcomes. Moreover, folate-related anemia during childhood and adolescence might predispose children to further infections and disease. The role of folic acid in prevention of neural tube defects (NTD) is now established, and several studies suggest that this protection may extend to some other birth defects. In terms of maternal health, clinical vitamin B12 deficiency may be a cause of infertility or recurrent spontaneous abortion. Starting pregnancy with an inadequate vitamin B12 status may increase risk of birth defects such as NTD, and may contribute to preterm delivery, although this needs further evaluation. Furthermore, inadequate vitamin B12 status in the mother may lead to frank deficiency in the infant if sufficient fetal stores of vitamin B12 are not laid down during pregnancy or are not available in breastmilk. However, the implications of starting pregnancy and lactation with low vitamin B12 status have not been sufficiently researched.

Homocysteine concentration, related B vitamins, and betaine in pregnant women recruited to the Seychelles Child Development Study

BACKGROUND

Both folate and betaine are important predictors of total homocysteine (tHcy) during pregnancy. However, studies to date have only been undertaken in populations with Western dietary patterns.

OBJECTIVE

We investigated the predictors of tHcy in pregnant women recruited in the Seychelles, a population where access to fortified foods is limited and where women habitually consume diets rich in fish, eggs, rice, and fruit.

DESIGN

Pregnant women (n = 226) provided blood samples at enrollment, at week 28 of gestation, and at delivery. Cord blood was obtained from a subset of participants (n = 135).

RESULTS

As in other studies, maternal tHcy was lower during pregnancy than at delivery, whereas folate and vitamin B-12 status declined significantly to delivery. Despite low maternal folate status at delivery (median: 9.0 nmol/L), with 35% of women in the deficient range (serum folate: <6.8 nmol/L), cord blood folate status (median: 40.2 nmol/L) was similar to concentrations reported in Western populations. Folate was a significant predictor of tHcy at all time points (P < 0.001). In contrast with previous studies, betaine was only a significant predictor of maternal tHcy (P < 0.001) when the essential amino acid methionine was low.

CONCLUSIONS

The current study reports 2 important findings. First, fetal requirements for folate are paramount, such that cord blood folate status is maintained, even when maternal status is low. Second, betaine is a significant predictor of tHcy in pregnant women with low serum folate and low serum methionine concentrations.

Effects of concentrations of cyanocobalamin in the gestation diet on some criteria of vitamin B12 metabolism in first-parity sows1,2

In swine nutrition, little is known about the role of vitamin B(12) in the reproductive processes. The current study was undertaken to obtain information on the dose-response pattern of different metabolic criteria related to the homeostasis of vitamin B(12) and homocysteine in gestating sows receiving various concentrations of dietary vitamin B(12) (cyanocobalamin). Homocysteine is a detrimental intermediate metabolite of the vitamin B(12)-dependent remethylation pathway of Met. Forty nulliparous (Large White x Landrace) sows were randomly assigned during gestation to dietary treatments containing 5 concentrations of cyanocobalamin (0, 20, 100, 200, or 400 microg/kg). During lactation, a diet containing 25 microg of cyanocobalamin/kg (as-fed) was given to all sows. During gestation, plasma vitamin B(12) increased as concentrations of dietary cyanocobalamin increased (linear and quadratic, P < 0.01) and the effect persisted during lactation (21 d postpartum) both in plasma (linear and quadratic, P < 0.05) and the liver (linear and quadratic, P < 0.04). Plasma homocysteine decreased with concentrations of cyanocobalamin provided to sows during gestation (linear, quadratic, and cubic, P < 0.01). At parturition, vitamin B(12) in colostrum increased as concentrations of cyanocobalamin increased (linear and quadratic, P < 0.01), but the treatment effect persisted (linear, P = 0.01) only up to 1 d postfarrowing. However, in piglets there was no treatment effect (P = 0.59) on plasma vitamin B(12) before colostrum intake, but a linear effect of concentrations of cyanocobalamin (P = 0.04) was observed 1 d later. Plasma homocysteine in piglets during lactation decreased with increasing concentrations of cyanocobalamin given to sows in gestation (linear and quadratic, P < 0.01). Based on a broken-line regression model, the concentrations of dietary cyanocobalamin that maximized plasma vitamin B(12) and minimized plasma homocysteine of sows during gestation were estimated to be 164 and 93 microg/kg, respectively. The maximal residual responses in sows and piglets during lactation were observed with treatments of 100 or 200 microg of cyanocobalamin/kg. The dietary cyanocobalamin concentration necessary to optimize the response of these metabolic criteria remains to be refined within lower and narrower ranges of cyanocobalamin concentrations (i.e., <200 mg/kg). Moreover, the biological significance of such concentrations of cyanocobalamin needs to be validated with performance criteria by using greater numbers of animals during several parities.

Homocysteine, cysteine, and related metabolites in maternal and fetal plasma in preeclampsia

Homocysteine is associated with endothelial dysfunction and cardiovascular disease, and elevated concentrations of homocysteine have been found in preeclampsia. The purpose of this study was to investigate maternal and fetal concentrations of total homocysteine and related metabolites (including cysteine, choline, and betaine), and possible associations with infant birth weight. Women with preeclampsia (n=47) and controls (n=51), who underwent cesarean section, were included. Maternal plasma, umbilical vein, and artery plasma were analyzed. Median concentrations of homocysteine, cysteine, choline, and betaine were significantly higher in women with preeclampsia than controls, both in maternal and fetal plasma. There were no differences in folate and vitamin B12 concentrations between the groups, neither for maternal nor fetal samples. Maternal homocysteine concentration was a negative predictor for birth weight only in the preeclampsia group. Elevated homocysteine and cysteine concentration in maternal circulation in preeclampsia is reflected in the fetal circulation. The clinical significance of elevated homocysteine and cysteine concentrations in maternal and fetal compartments in preeclampsia remain to be explored, both regarding fetal growth and development of disease later in life.

Risk factors for perinatal arterial stroke: a study of 60 mother-child pairs

The objective of the present study was to examine demographic, historical, and prothrombotic risk factors in infants with perinatal arterial stroke and their mothers. Risk factors were evaluated in 60 mother-child pairs with perinatal arterial stroke. Prothrombotic factors analyzed included the DNA mutations factor V Leiden, prothrombin 20210, MTHFR C677T and A1298C; serum activity levels for protein C, protein S, and antithrombin III; serum levels of lipoprotein(a); and, in the mothers, antiphospholipid antibodies. Boys predominated, 36:24. There were four twin sets. Sixty percent were term and 22% were post-date. Ten were large for gestational age. Five mothers had abdominal trauma. Nine mothers (15%) had preeclampsia. Emergency caesarean section was performed in 17 cases (28%). Eight placental exams revealed seven with abnormalities. Seizures were the presenting sign in 70%, and 30% presented with early handedness or cerebral palsy. Prothrombotic risk factors were found in 28 of 51 mothers (55%) and 30 of 60 children (50%). Forty-one pairs (68%) had at least one abnormality in mother, child, or both. Long-term sequelae included cerebral palsy (40 of 51; 78%), cognitive impairment (35 of 51; 68%), seizures (23 of 51; 45%), and microcephaly (26 of 51; 51%). Perinatal arterial stroke is the result of multifactorial, synergistic fetal and maternal factors among which the prothrombotic factors, both fetal and maternal, appear significant.

Fortified mineral water improves folate status and decreases plasma homocysteine concentration in pregnant women

OBJECTIVES

There is no mandatory folic acid fortification of food in Finland. We investigated the effects of mineral water fortified with folic acid, vitamins B6, B12, D and calcium on serum and erythrocyte folate concentrations, serum vitamin B12 and plasma homocysteine concentrations in pregnancy.

DESIGN

A randomized, controlled, double-blind, parallel-group intervention study.

METHODS

Seventy-four pregnant women were recruited from two health care units. The study began at the eleventh week with a two-week run-in period, followed by an eight-week intervention period. The diet was monitored by food records. During the intervention, subjects consumed 1000 mL/day fortified or normal mineral water. The pregnancies were monitored carefully.

RESULTS

The folate intake was 255 microg/day in the study group and 274 microg/day in the controls. Serum folate concentrations increased in the study group by 10.3 nmol/L and decreased in the controls by 2.7 nmol/L (P<0.05) during the study. The erythrocyte folate concentrations increased in the study group by 360.9 nmol/L and in the controls by 195.6 nmol/L (P=0.004) and serum homocysteine concentrations fell by 1.1 micromol/L and by 0.3 micromol/L, respectively (P<0.05).

CONCLUSIONS

Finnish pregnant women have low dietary folate intake. Fortified mineral water improved folate status and reduced plasma homocysteine concentrations in the pregnant subjects.

Association between decreased vitamin levels and MTHFR, MTR and MTRR gene polymorphisms as determinants for elevated total homocysteine concentrations in pregnant women

OBJECTIVES

To examine the association between methylenetetrahydrofolate reductase (MTHFR) (C677T and A1298C), methionine synthase (MTR) A2756G and methionine synthase reductase (MTRR) A66G gene polymorphisms and total homocysteine (tHcy), methylmalonic acid (MMA) and S-adenosylmethionine/S-adenosylhomocysteine (SAM/SAH) levels; and to evaluate the potential interactions with folate or cobalamin (Cbl) status.

SUBJECTS/METHODS

Two hundred seventy-five healthy women at labor who delivered full-term normal babies. Cbl, folate, tHcy, MMA, SAM and SAH were measured in serum specimens. The genotypes for polymorphisms were determined by PCR-restriction fragment length polymorphism (RFLP).

RESULTS

Serum folate, MTHFR 677T allele and MTR 2756AA genotypes were the predictors of tHcy levels in pregnant women. Serum Cbl and creatinine were the predictors of SAM/SAH ratio and MMA levels, respectively. The gene polymorphisms were not determinants for MMA levels and SAM/SAH ratios. Low levels of serum folate were associated with elevated tHcy in pregnant women, independently of the gene polymorphisms. In pregnant women carrying MTHFR 677T allele, or MTHFR 1298AA or MTRR 66AA genotypes, lower Cbl levels were associated with higher levels of tHcy. Lower SAM/SAH ratio was found in MTHFR 677CC or MTRR A2756AA genotypes carriers when Cbl levels were lower than 142 pmol/l.

CONCLUSIONS

Serum folate and MTHFR C677T and MTR A2576G gene polymorphisms were the determinants for tHcy levels. The interaction between low levels of serum Cbl and MTHFR (C677T or A1298C) or MTRR A66G gene polymorphisms was associated with increased tHcy.

Folate and human reproduction

The influence of folate nutritional status on various pregnancy outcomes has long been recognized. Studies conducted in the 1950s and 1960s led to the recognition of prenatal folic acid supplementation as a means to prevent pregnancy-induced megaloblastic anemia. In the 1990s, the utility of periconceptional folic acid supplementation and folic acid food fortification emerged when they were proven to prevent the occurrence of neural tube defects. These distinctively different uses of folic acid may well be ranked among the most significant public health measures for the prevention of pregnancy-related disorders. Folate is now viewed not only as a nutrient needed to prevent megaloblastic anemia in pregnancy but also as a vitamin essential for reproductive health. This review focuses on the relation between various outcomes of human reproduction (ie, pregnancy, lactation, and male reproduction) and folate nutrition and metabolism, homocysteine metabolism, and polymorphisms of genes that encode folate-related enzymes or proteins, and we identify issues for future research.

Antenatal supplementation with micronutrients and biochemical indicators of status and subclinical infection in rural Nepal

BACKGROUND

Previously we showed that women in rural Nepal experience multiple micronutrient deficiencies in early pregnancy.

OBJECTIVE

This study examined the effects of daily antenatal micronutrient supplementation on changes in the biochemical status of several micronutrients during pregnancy.

DESIGN

In Nepal, we conducted a randomized controlled trial in which 4 combinations of micronutrients (folic acid, folic acid + iron, folic acid + iron + zinc, and a multiple micronutrient supplement containing folic acid, iron, zinc, and 11 other nutrients) plus vitamin A, or vitamin A alone as a control, were given daily during pregnancy. In a subsample of subjects (n = 740), blood was collected both before supplementation and at approximately 32 wk of gestation.

RESULTS

In the control group, serum concentrations of zinc, riboflavin, and vitamins B-12 and B-6 decreased, whereas those of copper and alpha-tocopherol increased, from the first to the third trimester. Concentrations of serum folate, 25-hydroxyvitamin D, and undercarboxylated prothrombin remained unchanged. Supplementation with folic acid alone or folic acid + iron decreased folate deficiency. However, the addition of zinc failed to increase serum folate, which suggests a negative inhibition; multiple micronutrient supplementation increased serum folate. Folic acid + iron + zinc failed to improve zinc status but reduced subclinical infection. Multiple micronutrient supplementation decreased the prevalence of serum riboflavin, vitamin B-6, vitamin B-12, folate, and vitamin D deficiencies but had no effect on infection.

CONCLUSIONS

In rural Nepal, antenatal supplementation with multiple micronutrients can ameliorate, to some extent, the burden of deficiency. The implications of such biochemical improvements in the absence of functional and health benefits remain unclear.