Maternal serum folacin levels during and after normal pregnancy

Folic acid: The key to a healthy pregnancy - A prospective study on fetomaternal outcome

Objectives

The objective of the study is to study the fetomaternal outcome associated with folic acid deficiency in pregnancy.

Materials and Methods

This hospital-based observational study was conducted in the Department of Obstetrics and Gynaecology at Base Hospital, Delhi Cantt, and a total of 351 participants were enrolled who were fulfilling the inclusion criteria. The plasma folic acid level of the selected patients was measured in the booking visit by automated chemiluminescence assay. The cutoff levels of folic acid were taken at 8.6 ng/mL. Based on these values, the study population was divided into two groups, one with folic acid values <8.6 ng/mL and the other with values ≥8.6 ng/mL. Plasma Vitamin B12 levels were measured to check for any concurrent deficiencies. Obstetric outcomes included first- and second-trimester miscarriages, development of anemia, gestational hypertension/preeclampsia, gestational diabetes mellitus, hypothyroidism, placental abruption, and intrauterine fetal growth restriction (FGR). Furthermore, the period of gestation at delivery, fetal weights, APGAR scores at 5 min were documented. The study also considered fetal neural tube defects, intrauterine fetal demise for data collection. Collected data were analyzed statistically to find the association of the above-mentioned outcomes with levels of folic acid.

Results

The rate of preterm deliveries was significantly higher in the folic acid group with levels <8.6 ng/mL (16.94%). The incidence of small for gestational age/FGR was higher in the folic acid group with levels <8.6 ng/mL (27.11%) compared to the high folic acid group with levels ≥8.6 ng/mL (13.38%). The differences in the incidence of anemia, gestational hypertension, gestational diabetes, and preeclampsia between the two groups were not statistically significant and no cases of intrauterine fetal demise or placental abruption were observed in either group. Moreover, there was no significant difference in the relative risk of low Apgar scores at 5 min between the two groups.

Conclusion

The present study suggests that low folic acid levels during pregnancy are associated with a higher risk of adverse pregnancy outcomes such as anemia, miscarriages, preterm delivery, and FGR. Therefore, adherence to nutritional recommendation of folic acid supplementation during pregnancy is essential to prevent these adverse outcomes.

Maternal micronutrient disturbance as risks of offspring metabolic syndrome

Metabolic syndrome (MetS) is defined as a constellation of individual metabolic disturbances, including central obesity, hypertension, dyslipidemia, and insulin resistance. The established pathogenesis of MetS varies extensively with gender, age, ethnic background, and nutritional status. In terms of nutritional status, micronutrients are more likely to be discounted as essential components of required nutrition than macronutrients due to the small amount required. Numerous observational studies have shown that pregnant women frequently experience malnutrition, especially in developing and low-income countries, resulting in chronic MetS in the offspring due to the urgent and increasing demands for micronutrients during gestation and lactation. Over the past few decades, scientific developments have revolutionized our understanding of the association between balanced maternal micronutrients and MetS in the offspring. Examples of successful individual, dual, or multiple maternal micronutrient interventions on the offspring include iron for hypertension, selenium for type 2 diabetes, and a combination of folate and vitamin D for adiposity. In this review, we aim to elucidate the effects of maternal micronutrient intake on offspring metabolic homeostasis and discuss potential perspectives and challenges in the field of maternal micronutrient interventions.

Multiple Indicators of Undernutrition, Infection, and Inflammation in Lactating Women Are Associated with Maternal Iron Status and Infant Anthropometry in Panama: The MINDI Cohort

Maternal infections, nutrient deficiencies, and inflammation (MINDI) co-exist in lactating indigenous women in Panama, but their impact on maternal iron status and infant growth is unknown. For this secondary analysis of cross-sectional data of lactating mothers from our MINDI cohort, we investigated associations of MINDI variables with maternal anemia, elevated serum transferrin receptor (sTfR), low serum iron, hepcidin, ferritin, and infant weight-for-age (WAZ), length-for-age (LAZ), and head-circumference-for-age (HCAZ) Z-scores in 99 mother-infant dyads. A bootstrapping resampling procedure preselected covariates for inclusion in multivariable regressions models from chronic maternal infections and nutritional status [folate, vitamins A, D, retinol-binding protein (RBP), insulin-growth factor-1 (IGF-1)] and inflammation [C-reactive protein (CRP), cytokines, platelet indices] indicators. Anemia was prevalent (53.5%) but underestimated due to widespread low plasma volume (<2.2 L, 79.9%) and was associated with indicators of malnutrition [lower IGF-1, body mass index (BMI), vitamin D, and intake of green/leafy vegetables], but not inflammation. Higher CRP was associated with lower serum iron, and higher hepcidin and ferritin, whereas maternal platelets were associated with lower HCAZ (β = −0.22), WAZ (β = −0.17), and LAZ (β = −0.17). Higher LAZ was also associated with maternal serum vitamin D (β = 0.23), whereas maternal iron supplementation lowered LAZ (β = −0.22). Assessment of iron status in this MINDI cohort is complex and supplementation strategies must consider consequences for both the mother and the infant.

Distribution of 5-Methyltetrahydrofolate and Folic Acid Levels in Maternal and Cord Blood Serum: Longitudinal Evaluation of Japanese Pregnant Women

“Total” folate in blood has usually been measured to evaluate the folate status of pregnant women. However, folate is composed of many metabolites. The main substrate is 5-methyltetrahydrofolate (5-MTHF), with folic acid (FA) representing a very small component as an unmetabolized species in blood. We longitudinally evaluated 5-MTHF, FA and total homocysteine in maternal and cord blood from Japanese pregnant women. Subjects were 146 pregnant women who participated in the Chiba study of Mother and Child Health (C-MACH) prospective cohort study. Sera were obtained in early and late pregnancy, at delivery, and from cord blood. Species levels were measured by isotope-dilution mass spectrometry. Both 5-MTHF and FA levels were lower than reported levels from pregnant women in populations from countries with mandatory FA fortification. As gestational age progressed, serum 5-MTHF levels decreased, whereas serum FA levels were slightly reduced only at delivery compared to early pregnancy. A significant negative association between serum 5-MTHF and total homocysteine was shown at all examined times, but no associations with FA were evident. At delivery, cord 5-MTHF was significantly higher than maternal levels, while FA again showed no significant correlation. These results suggest that 5-MTHF is actively transported to the fetus through placental transporters and may reflect folate status during pregnancy as a physiologically important species.

The MTHFR 677C>T polymorphism is associated with unmetabolized folic acid in breast milk in a cohort of Canadian women

BACKGROUND

Maternal nutrition and genetics are determinants of breast-milk nutrient composition and, as such, are determinants of the nutritional exposure of breastfed infants.

OBJECTIVES

The aim of this study was to determine whether common maternal single nucleotide polymorphisms (SNPs) in folate-dependent enzymes are associated with breast-milk folate content in a cohort of mothers enrolled in the Maternal-Infant Research on Environmental Chemicals (MIREC) study.

METHODS

The MIREC study is a Canadian prospective pregnancy cohort study that recruited 2001 participants between 2008 and 2011. Five folate-related SNPs-MTHFR 677C>T (rs1801133), MTHFR 1298A>C (rs1801131), MTHFR 1793G>A (rs2274976), MTR 2756A>G (rs1805087), and MTRR 66A>G (rs1801394)-were genotyped. Breast milk was sampled ∼1 mo postpartum, and tetrahydrofolate (THF), 5-methyl-THF, 5-formyl-THF, 5,10-methenyl-THF, and unmetabolized folic acid (UMFA) were measured using liquid chromatography-tandem mass spectrometry in a subset of participants (n = 551). Associations were assessed using Wald's test. Associations were considered significant if P ≤ 0.01 (Bonferroni correction for multiple testing).

RESULTS

None of the SNPs were associated with total breast-milk folate. However, the MTHFR 677C>T SNP was associated with breast-milk UMFA (R2 = 0.01; unadjusted P = 0.004), explaining a small portion of total variance; this association remained significant when adjusted for other covariates, including supplemental folic acid consumption. The MTHFR 1793G>A and MTRR 66A>G SNPs tended to be associated with 5-methyl-THF (R2 = 0.008, P = 0.04) and reduced folates (THF + 5-methyl-THF + 5-formyl-THF + 5,10-methenyl-THF; R2 = 0.01, P = 0.02), respectively.

CONCLUSIONS

We found that total breast-milk folate content was not associated with any of the folate-related SNPs examined. The association between the MTHFR 677C>T SNP and breast-milk UMFA, albeit modest, highlights the need to better understand the determinants of breast-milk folate and the impact they might have on milk folate bioavailability.

Total folate and unmetabolized folic acid in the breast milk of a cross-section of Canadian women

Background: Folate requirements increase during pregnancy and lactation. It is recommended that women who could become pregnant, are pregnant, or are lactating consume a folic acid (FA)-containing supplement.Objectives: We sought to determine breast-milk total folate and unmetabolized folic acid (UMFA) contents and their relation with FA-supplement use and doses in a cohort of Canadian mothers who were enrolled in the MIREC (Maternal-Infant Research on Environmental Chemicals) study.Design: Breast-milk tetrahydrofolate (THF), 5-methyl-THF, 5-formyl-THF, 5,10-methenyl-THF, and UMFA were measured with the use of liquid chromatography-tandem mass spectrometry (n = 561). Total daily supplemental FA intake was based on self-reported FA-supplement use.Results: UMFA was detectable in the milk of 96.1% of the women. Total daily FA intake from supplements was associated with breast folate concentration and species. Breast-milk total folate was 18% higher (P < 0.001) in supplement users (n = 401) than in nonusers (n = 160), a difference driven by women consuming >400 μg FA/d (P ≤ 0.004). 5-Methyl-THF was 19% lower (P < 0.001) and UMFA was 126% higher (P < 0.001) in supplement users than in nonusers. Women who consumed >400 μg FA/d had proportionally lower 5-methyl-THF and higher UMFA than did women who consumed ≤400 μg FA/d.Conclusions: FA-supplement use was associated with modestly higher breast-milk total folate. Detectable breast-milk UMFA was nearly ubiquitous, including in women who did not consume an FA supplement. Breast-milk UMFA was proportionally higher than 5-methyl-THF in women who consumed >400 μg FA/d, thereby suggesting that higher doses exceed the physiologic capacity to metabolize FA and result in the preferential uptake of FA in breast milk. Therefore, FA-supplement doses >400 μg may not be warranted, especially in populations for whom FA fortification is mandatory.

Effects of birth spacing on maternal, perinatal, infant, and child health: a systematic review of causal mechanisms

This systematic review of 58 observational studies identified hypothetical causal mechanisms explaining the effects of short and long intervals between pregnancies on maternal, perinatal, infant, and child health, and critically examined the scientific evidence for each causal mechanism hypothesized. The following hypothetical causal mechanisms for explaining the association between short intervals and adverse outcomes were identified: maternal nutritional depletion, folate depletion, cervical insufficiency, vertical transmission of infections, suboptimal lactation related to breastfeeding-pregnancy overlap, sibling competition, transmission of infectious diseases among siblings, incomplete healing of uterine scar from previous cesarean delivery, and abnormal remodeling of endometrial blood vessels. Women's physiological regression is the only hypothetical causal mechanism that has been proposed to explain the association between long intervals and adverse outcomes. We found growing evidence supporting most of these hypotheses.

Periconceptional folate deficiency and implications in neural tube defects

Nutritional deficiencies are preventable etiological and epigenetic factors causing congenital abnormalities, first cause of infant mortality. Folate deficiency has a well-established teratogenic effect, leading to an increasing risk of neural tube defects. This paper highlights the most recent medical literature about folate deficiency, be it maternal or paternal. It then focuses on associated deficiencies as nutritional deficiencies are multiple and interrelated. Observational and interventional studies have all been consistent with a 50–70% protective effect of adequate women consumption of folates on neural tube defects. Since strategies to modify women's dietary habits and vitamin use have achieved little progress, scientific as well as political effort is mandatory in order to implement global preventive public health strategies aimed at improving the alimentation of women in reproductive age, especially folic acid supplementation. Even with the recent breakthrough of fetal surgery for myelomeningocele, the emphasis should still be on prevention as the best practice rather than treatment of neural tube defects.

Micronutrients and women of reproductive potential: required dietary intake and consequences of dietary deficiency or excess. Part I--Folate, Vitamin B12, Vitamin B6

This two-part review highlights micronutrients for which either public health policy has been established or for which new evidence provides guidance as to recommended intakes during pregnancy. One pivotal micronutrient is folate, the generic name for different forms of a water-soluble vitamin essential for the synthesis of thymidylate and purines and, hence, DNA. For non-pregnant adult women the recommended intake is 400 μg/day dietary folate equivalent. For women capable of becoming pregnant an additional 400 μg/day of synthetic folic acid from supplements or fortified foods is recommended to reduce the risk of neural tube defects (NTD). The average amount of folic acid received through food fortification (grains) in the US is only 128 μg/day, emphasising the need for the supplemental vitamin for women of reproductive age. Vitamin B12 (cobalamin) is a cofactor required for enzyme reactions, including generation of methionine and tetrahydrofolate. B12 is found almost exclusively in foods of animal origin (meats, dairy products); therefore, vegetarians are at greatest risk for dietary vitamin B12 deficiency and should be supplemented. Vitamin B6 is required for many reactions, primarily in amino acid metabolism. Meat, fish and poultry are good dietary sources. Supplementation beyond routine prenatal vitamins is not recommended.

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.

Relationship between dietary folate intakes, maternal plasma total homocysteine and B-vitamins during pregnancy and fetal growth in Japan

BACKGROUND

Adequate folate status in pregnancy is important for satisfactory pregnancy outcome.

AIM OF THE STUDY

The objective of the present study was to evaluate folate status in healthy pregnant women by assessing dietary folate intakes and measuring changes in folate-related biomarkers including plasma tHcy, serum vitamin B(12) (B(12)), and serum and RBC folate concentrations in each trimester and to examine their relation to fetal growth.

METHODS

From 94 pregnant women, 3-day-dietary records were obtained and blood was collected for plasma total homocysteine (tHcy), serum B(12), and serum and red-blood cell (RBC) folate measurements. Infant anthropometric measurements were made immediately after birth.

RESULTS

Average folate intake was less than 300 microg/day with a mean energy intake of about 1800 kcal. Mean serum and RBC folate concentrations declined significantly during gestation (p < 0.05). Mean serum B(12) also significantly decreased (p < 0.01), whereas plasma tHcy increased from 5.1 in the first trimester to 5.9 micromol/l in the third trimester (p < 0.01). Multiple regression analyses, after controlling for maternal age, parity and pre-pregnancy body-mass index indicated that a 1.0 micromol/l increase in plasma tHcy in the third trimester corresponded to a 151 g decrease in birth weight (p < 0.01). Neither B(12) nor folate concentrations in all three trimesters showed any significant associations with birthweight. Plasma pyridoxal-5'-phosphate concentrations were markedly low, and were consistent with low intake of vitamin B(6) in our population.

CONCLUSION

Our data suggest that higher plasma tHcy in the third trimester is a predictor of lower birth weight. In general, the dietary intake of B-vitamins and energy may be inadequate in our population, suggesting intervention is necessary.

A multivitamin supplementation and education intervention as an effective means of increasing multivitamin use among postpartum women of Mexican origin

Postpartum Hispanic women in the USA are at elevated risk for neural tube defects in subsequent pregnancies from the combined effects of ethnicity, folate depletion from the prior pregnancy and lactation, and high parity rates with short inter-birth intervals. This study evaluated an education programme and distribution of a 3-month starter package of multivitamins among Hispanic women attending nutrition clinics for low-income women in El Paso, Texas. At 1-6 weeks postpartum, 329 subjects were selected to receive education only, multivitamins only, education and multivitamins, or no intervention. Multivariable regression obtained odds ratios (OR) and 95% confidence intervals [CI] to measure the association between intervention status and self-reported multivitamin use at least four times per week at 6 and 12 months postpartum, while controlling for potential confounding variables. Multivitamin distribution was related to consumption at both 6 months (OR = 3.5 [95% CI 1.1, 11.2]) and 12 months (OR = 6.5 [95% CI 1.5, 28.3]). Multivitamins plus education was most effective in increasing multivitamin use at both periods: 6 months (OR = 4.0 [95% CI 1.53, 11.7]) and 12 months (OR = 6.4 [95% CI 1.7, 24.2]). At enrolment, 66% of women regularly took vitamins, and approximately 35% took them at both 6 and 12 months postpartum. The education intervention alone was not associated with multivitamin use at either 6 months (OR = 0.79 [95% CI 0.3, 2.4]) or 12 months (OR = 3.1 [95% CI 0.8, 12.1]). Multivitamin use declines precipitously during postpartum at the time Hispanic women may be susceptible to a subsequent pregnancy. This study provides evidence that multivitamin starter packs sustain multivitamin usage up to 1 year postpartum for a specific high-risk group, but the effect of educational intervention alone should be further studied.

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.

Folate and vitamin B12 in relation to lactation: a 9-month postpartum follow-up study

OBJECTIVE

To investigate the relation between lactation and markers of folate and vitamin B12 (B12) deficiency in women with and without vitamin supplementation.

DESIGN

A 9-month follow-up study.

SUBJECTS AND METHODS

Blood samples from 91 women, who gave birth to a single healthy child, were collected 3 weeks, 4 and 9 months postpartum and analysed for circulating level of homocysteine (tHcy), methylmalonic acid (MMA), folate and B12. The participants were categorized as exclusively, partly or not breast-feeding dependent on the degree of lactation 4 months postpartum. During follow-up, lifestyle factors were recorded by structured interviews.

RESULTS

Among 72 exclusively breast-feeding women, the median (10-90% percentile) tHcy was 5.8 (3.1-8.3) micromol/l 3 weeks postpartum, 6.1 (4.1-10.3) micromol/l 4 months postpartum and 5.3 (3.6-8.7) micromol/I 9 months postpartum. At 9 months postpartum, none of the women breast-fed exclusively. No significant change occurred in the concentration of B12 and folate. Exclusively breast-feeding women without vitamin supplementation had higher median tHcy than supplemented exclusively breast-feeding women 4 and 9 months postpartum (7.0 vs 5.4 micromol/l (P < 0.001) and 5.8 vs 4.5 micromol/l (P = 0.003), respectively). Six women had increased (>15 micromol/l) tHcy; four of these were unsupplemented and exclusively breast-feeding.

CONCLUSION

We found no overall indication of depletion of the folate and B12 stores during the lactation period in this population. However, folate-supplemented women had lower tHcy and higher folate levels, suggesting a beneficial effect of supplementation with folate throughout lactation.

Nutrition in pregnancy: mineral and vitamin supplements

Pregnancy is associated with physiologic changes that result in increased plasma volume and red blood cells and decreased concentrations of circulating nutrient-binding proteins and micronutrients. In many developing countries, these physiologic changes can be aggravated by undernutrition, leading to micronutrient deficiency states, such as anemia, that can have disastrous consequences for both mothers and newborn infants. Multiple micronutrients are often taken by pregnant women in developed countries, but their benefits are limited, except for prophylactic folic acid taken during the periconceptional period. Women in developing countries may benefit from multiple-micronutrient prophylaxis in pregnancy, but the underlying basis and rationale for changing from supplementation with iron and folate to supplementation with multiple micronutrients has not been debated in the context of existing program objectives. There is an urgent need for this discussion so that both program effectiveness and program efficacy can be improved.

Declining levels of erythrocyte folate during the postpartum period among Hispanic women living on the Texas-Mexico border

Hispanic women have higher parity and shorter interbirth intervals than women of other ethnic groups. Thus, they are more likely to become pregnant relatively soon after giving birth, which may place these women at risk of low or deficient levels of specific nutrients. Folic acid is of particular concern because recent studies suggest that maternal use of folic acid supplements may be associated with better reproductive outcomes. The purpose of this study was to assess folic acid levels in postpartum Hispanic women. Using a cross-sectional design, we measured erythrocyte folate values for 188 low-income Hispanic women 1-12 months postpartum who were receiving services at the Women, Infants, and Children (WIC) clinics in El Paso, Texas. An interview was administered to collect information on diet, vitamin use, and method of infant feeding. Mean erythrocyte folate levels decreased from >1300 ng/ml during the first 4 months postpartum to a low of 1017 ng/ml by 12 months postpartum, for an overall decrease of approximately 23% (p = 0.004). Use of postpartum vitamin supplements was significantly associated with higher folate levels. However, only 35% of mothers used vitamins beyond 1 month postpartum. Study results suggest that these mothers may be at risk of developing low or deficient levels of folic acid during the postpartum period. Educational campaigns targeting these women as well as other groups of postpartum women should encourage them to comply with the U.S. Public Health Service recommendation that women of childbearing age consume 0.4 mg of folic acid daily.

Drug and environmental factors associated with adverse pregnancy outcomes. Part I: Antiepileptic drugs, contraceptives, smoking, and folate

OBJECTIVE

Part I of this review examines the relationship between antiepileptic drugs (AEDs) and pregnancy outcomes. Drug-induced folate deficiency and the role of AED metabolism are emphasized. Part II will discuss periconceptional folate supplementation for prevention of birth defects. Part III will discuss the mechanism of folate's protective effect, therapeutic recommendations, compliance, and cost.

DATA SOURCES

A MEDLINE search was conducted for journal articles published through December 1997. Additional sources were obtained from Current Contents and citations from the references obtained. Search terms included phenytoin, carbamazepine, phenobarbital, primidone, valproic acid, oral contraceptives, clomiphene, drug-induced abnormalities, spina bifida, anencephaly, neural tube defect, folate, folic acid, and folic acid deficiency.

STUDY SELECTION

Relevant animal and human studies examining the effects of AEDs, smoking, and oral contraceptives on folate status and pregnancy outcome are reviewed.

DATA EXTRACTION

Studies and case reports were interpreted. Data extracted included dosing, serum and red blood cell folate concentrations, teratogenicity of anticonvulsant medications, metabolism of AEDs and folate, and genetic susceptibility to AED-induced teratogenicity.

DATA SYNTHESIS

Low serum and red blood cell folate concentrations are associated with adverse pregnancy outcomes. Decreases in serum folate are seen with AEDs, oral contraceptives, and smoking. Since similar birth defects are observed with multiple AEDs, metabolism of aromatic AEDs to epoxide metabolites and genetic factors may play a role in teratogenesis.

CONCLUSIONS

Adequate prepregnancy planning is essential for women who have epilepsy. Women receiving folate-lowering drugs may be at increased risk of adverse pregnancy outcomes. Therefore, epileptic women contemplating pregnancy should be treated with the minimum number of folate-lowering drugs possible and receive folic acid supplementation.

Folate economy in pregnancy

Pregnant women are prone to becoming folate deficient because there is a significant increase in folate requirement during pregnancy and folate intakes of pregnant women are often insufficient. Reduced folate levels in blood and neutrophilic hypersegmentation reflect a negative folate balance. Possible consequences of a low maternal folate status may be pregnancy complications such as abortion, abortus imminens, abruptio placentae, and congenital malformations. The role of folic acid in the etiology of neural tube defects has been discussed for decades. The importance of an adequate maternal folate status in the prevention of neural tube defects has been demonstrated by observational and controlled intervention trials. However, the mechanism of the protective effect of periconceptional folate supplementation is not completely understood. Metabolic disorders are probably involved in the pathogenesis of neural tube defects so that a relative folate shortage rather than folate deficiency seems to be responsible for the disturbed neural tube development, which can be compensated for by a higher folate intake.

Changes of some vitamin levels during and after normal pregnancy

Most vitamin status parameters change significantly during pregnancy. A number of factors have been associated with this hypovitaminaemia of pregnancy. From our data, it was concluded that the initial value of a vitamin status parameter was by far the main determinant of the changes of vitamin levels during pregnancy: the higher the value, the steeper the decrease. Some hormonal variables were associated with these changes as well. This is highly suggestive of a resetting of vitamin homeostasis in blood, with a retention of vitamins in maternal tissues. The postpartum changes of vitamin levels provide insight into the 'net cost' of vitamins during pregnancy. Most serum blood levels of vitamins normalized shortly after delivery. Serum vitamin B6 levels increased slowly with 25% below the acceptable range at 6 months postpartum. However, the GGOT stimulation ratio, indicative for vitamin B6 cellular content, was completely normal at the time. Serum folacin was the only exception, with 45% serum levels in the marginal or deficient range; 20% of this group had deficient or marginal red cell folacin levels as well. This indicates that the 'net cost' of folacin during pregnancy is considerable, and repletion of folacin stores takes more than 6 months.

Elevated folate levels in amniotic fluid after oral supplementation

During oral supplementation of 5 mg folic acid and 1 microgram vitamin B12, the daily folate levels in plasma, red cells and midtrimester amniotic fluid were significantly higher in ten pregnant women during the 15th-18th week of menstrual age as compared to ten non-supplemented women serving as controls. In the control group as well as in the supplemented group, the folate concentrations in amniotic fluid were found to be lower than in the corresponding maternal plasma and red cells. Of all women investigated there was a significant positive correlation between maternal plasma folate concentrations and amniotic fluid levels (r = 0.72, p less than 0.001) and no correlation between red cell folate concentrations and amniotic fluid levels (r = 0.30, p = 0.22). Oral supplementation of vitamin B12 did not elevate maternal blood concentrations and amniotic fluid levels. Vitamin B12 levels in amniotic fluid in this group and controls were always higher than in plasma. These data suggest that the orally administrated dosages of folic acid unlike those of vitamin B12 augment both plasma, red cells and amniotic fluid levels.