Status of plasma folate after folic acid fortification of the food supply in pregnant African American women and the influences of diet, smoking, and alcohol consumption

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.

Maternal Cotinine Levels and Red Blood Cell Folate Concentrations in the Periconceptual Period

OBJECTIVES

Studies have examined the association between tobacco use and folate levels in pregnancy, yet few have assessed this relation using objective and accurate measures of both smoking and folate. In this study, we evaluated the association between maternal cotinine levels and periconceptional red blood cell (RBC) folic acid reserves in a cohort of low-income pregnant mothers.

METHODS

Smoking information, based on salivary cotinine, a highly sensitive and specific tobacco smoke exposure biomarker, was used. Furthermore, folate was assessed using RBC folate, an indicator of long-term folate storage. Participants were early to mid-trimester pregnant women who received antenatal care between 2011 and 2015 at the Genesis Clinic of Tampa (Florida). A total of 496 women were enrolled in the study. Associations between smoking status/maternal salivary cotinine concentrations, sociodemographic factors, and folate concentrations were investigated using Tobit regression analyses.

RESULTS

The mean folate level of the participants was 718.3 ± 183.2 ng/mL, and only 2 (0.4%) participants were deficient in folate. We observed no significant difference in folate levels by smoking status. In contrast, salivary cotinine levels were significantly associated with decreased RBC folate concentrations (β -11.43, standard error 5.45, P = 0.032). Prepregnancy maternal body mass index, gestational age, stress, and depression also were associated with folate levels.

CONCLUSIONS

Low RBC folate is associated with perinatal factors, including high maternal cotinine levels, body mass index, stress, and depression. The effect of low folate levels among smokers cannot be overemphasized, considering that tobacco products not only reduce folate levels but also decrease the bioutilization of folate.

Association between maternal periconceptional alcohol consumption and neural tube defects: Findings from the National Birth Defects Prevention Study, 1997-2011

BACKGROUND

Neural tube defects (NTD)s are common birth defects with a multifactorial etiology. Findings from human studies examining environmental (non-inherited) exposures tend to be inconclusive. In particular, although animal studies of alcohol exposure and NTDs support its teratogenic potential, human studies are equivocal. Using data from the National Birth Defects Prevention Study (NBDPS), associations between maternal periconceptional (1 month before through 1 month after conception) alcohol consumption and NTDs in offspring were examined.

METHODS

NTD cases and unaffected live born singleton controls with expected dates of delivery from October 1997-December 2011 were enrolled in the NBDPS. Interview reports of alcohol consumption (quantity, frequency, variability, type) from 1,922 case and 11,251 control mothers were analyzed. Crude and adjusted odds ratios (aOR)s and 95% confidence intervals (CI)s for alcohol consumption and all NTDs combined and selected subtypes (spina bifida, anencephaly, encephalocele) were estimated using unconditional logistic regression analysis.

RESULTS

Among mothers in the NBDPS, 28% of NTD case and 35% of control mothers reported any periconceptional alcohol consumption. For each measure of alcohol consumption, inverse associations were observed for all NTDs combined (aORs = 0.6-1.0). Results for NTD subtypes tended to be similar, but CIs for spina bifida and encephalocele were more likely to include the null.

CONCLUSIONS

These findings suggest a lack of positive associations between maternal periconceptional alcohol consumption and NTDs. Future studies should continue to evaluate the association between maternal alcohol consumption and NTDs in offspring accounting for methodological limitations such as potential misclassification from self-reported alcohol consumption.

Folic Acid Intake, Fetal Brain Growth, and Maternal Smoking in Pregnancy: A Randomized Controlled Trial

BACKGROUND

Folic acid supplementation during pregnancy plays an important role in fetal growth and development. To our knowledge, no experimental study has examined the effect of folic acid on fetal brain growth in women who smoke cigarettes during pregnancy.

OBJECTIVES

The aim of this study was to investigate the efficacy of higher-dose compared with standard-dose folic acid supplementation on prenatal fetal brain growth, measured by head circumference, brain weight, and brain-body weight ratio (BBR).

DESIGN

In this randomly assigned, double-blind, controlled clinical trial, we recruited 345 smoking pregnant women attending a community health center in Tampa, FL between 2010 and 2014. Participants were randomly assigned in a 1:1 ratio to receive either 0.8 mg folic acid/d (standard of care at the study center) or 4 mg folic acid/d (higher strength). Participants were also enrolled in a smoking cessation program. A 2-level linear growth model was used to assess treatment effect and factors that predict intrauterine growth in head circumference over time. Multiple linear regression analyses were conducted to estimate the effect of higher-strength folic acid on head circumference at birth, fetal brain weight, and fetal BBRs.

RESULTS

Mothers who received the higher dose of folic acid had infants with a 1.18 mm larger mean head circumference compared with infants born to mothers who received the standard dose, but this difference was not statistically significant (P = 0.2762). Higher-dose folic acid also had no significant effect on brain weight. The BBR of infants of mothers who received higher-dose folic acid was, however, 0.33 percentage points lower than that for infants of mothers who received the standard dose of folic acid (P = 0.044).

CONCLUSIONS

Infants of smokers in pregnancy may benefit from higher-strength maternal folic acid supplementation. We noted a decrease in the proportion of infants with impaired BBR among those on higher-dose folic acid. This trial was registered at clinicaltrials.gov as NCT01248260.

Folate, vitamin B12, and homocysteine in smoking-exposed pregnant women: A systematic review

Smoking exposure is associated with pregnancy complications, as are levels of folate, vitamin B12, and homocysteine. In nonpregnant adults, smoking exposure is associated negatively with folate and vitamin B12 levels and positively with homocysteine levels. A complete overview of the literature on this topic in pregnant women is lacking. To evaluate evidence of associations of maternal smoking exposure during pregnancy and levels of folate, homocysteine, and vitamin B12 in pregnancy and in cord blood, we searched MEDLINE, Embase, CINAHL, Cochrane, Scopus, Web of Science, and reference lists of relevant studies until August 2017. We selected studies in pregnant women describing the association of passive or active smoking and levels of folate, homocysteine, and/or vitamin B12. Data were extracted by two independent reviewers. We included 32 studies of 2,015 identified references with a total of 37,822 participants and more than 6,000 smokers. Twenty‐eight studies measured folate, 14 measured vitamin B12, and 13 measured homocysteine. Nineteen out of 28 studies assessing folate reported significantly lower levels in pregnant women exposed to smoking compared with those unexposed. Vitamin B12 levels were lower in smoking mothers in eight out of 14 studies. Homocysteine levels tended to be higher in mothers exposed to smoking. Smoking exposure during pregnancy is generally associated with lower folate and vitamin B12 levels and higher homocysteine levels. This may help raise further awareness about the consequences of smoking and the need to encourage stopping smoking in all, especially in pregnant women.

Fetal and neonatal exposure to nicotine leads to augmented hepatic and circulating triglycerides in adult male offspring due to increased expression of fatty acid synthase

While nicotine replacement therapy is assumed to be a safer alternative to smoking during pregnancy, the long-term consequences for the offspring remain elusive. Animal studies now suggest that maternal nicotine exposure during perinatal life leads to a wide range of adverse outcomes for the offspring including increased adiposity. The focus of this study was to investigate if nicotine exposure during pregnancy and lactation leads to alterations in hepatic triglyceride synthesis. Female Wistar rats were randomly assigned to receive daily subcutaneous injections of saline (vehicle) or nicotine bitartrate (1mg/kg/day) for two weeks prior to mating until weaning. At postnatal day 180 (PND 180), nicotine exposed offspring exhibited significantly elevated levels of circulating and hepatic triglycerides in the male offspring. This was concomitant with increased expression of fatty acid synthase (FAS), the critical hepatic enzyme in de novo triglyceride synthesis. Given that FAS is regulated by the nuclear receptor Liver X receptor (LXRα), we measured LXRα expression in both control and nicotine-exposed offspring. Nicotine exposure during pregnancy and lactation led to an increase in hepatic LXRα protein expression and enriched binding to the putative LXRE element on the FAS promoter in PND 180 male offspring. This was also associated with significantly enhanced acetylation of histone H3 [K9,14] surrounding the FAS promoter, a hallmark of chromatin activation. Collectively, these findings suggest that nicotine exposure during pregnancy and lactation leads to an increase in circulating and hepatic triglycerides long-term via changes in the transcriptional and epigenetic regulation of the hepatic lipogenic pathway.

Periconceptional maternal alcohol consumption and neural tube defects

BACKGROUND

Neural tube defects (NTD)s, which occur when the neural tube fails to close during early gestation, are some of the most common birth defects worldwide. Alcohol is a known teratogen and has been shown to induce NTDs in animal studies, although most human studies have failed to corroborate these results. Using data from the National Birth Defects Prevention Study, associations between maternal reports of periconceptional (1 month prior through 2 months postconception) alcohol consumption and NTDs were examined.

METHODS

NTD cases and unaffected live born control infants, delivered from 1997 through 2005, were included. Interview reports of alcohol consumption (quantity, frequency, variability, and type) were obtained from 1223 case mothers and 6807 control mothers. Adjusted odds ratios (aOR)s and 95% confidence intervals were estimated using multivariable logistic regression analysis.

RESULTS

For all NTDs combined, most aORs for any alcohol consumption, one or more binge episodes, and different type(s) of alcohol consumed were near unity or modestly reduced (≥ 0.7 < aOR ≤ 1.1) and were not statistically significant. Findings were similar for individual NTD subtypes.

CONCLUSIONS

These findings suggest no elevated association between maternal periconceptional alcohol consumption and NTDs. Underreporting of alcohol consumption, due to negative social stigma associated with alcohol consumption during pregnancy, and limited reports for mothers with early pregnancy loss of a fetus with an NTD may have affected the estimated odds ratios. Future studies should aim to increase sample sizes for less prevalent subtypes, reduce exposure misclassification, and improve ascertainment of fetal deaths and elective terminations.

Folic acid transport to the human fetus is decreased in pregnancies with chronic alcohol exposure

BACKGROUND

During pregnancy, the demand for folic acid increases since the fetus requires this nutrient for its rapid growth and cell proliferation. The placenta concentrates folic acid into the fetal circulation; as a result the fetal levels are 2 to 4 times higher than the maternal level. Animal and in vitro studies have suggested that alcohol may impair transport of folic acid across the placenta by decreasing expression of transport proteins. We aim to determine if folate transfer to the fetus is altered in human pregnancies with chronic alcohol consumption.

METHODOLOGY/PRINCIPAL FINDINGS

Serum folate was measured in maternal blood and umbilical cord blood at the time of delivery in pregnancies with chronic and heavy alcohol exposure (n = 23) and in non-drinking controls (n = 24). In the alcohol-exposed pairs, the fetal:maternal serum folate ratio was ≤ 1.0 in over half (n = 14), whereas all but one of the controls were >1.0. Mean folate in cord samples was lower in the alcohol-exposed group than in the controls (33.15 ± 19.89 vs 45.91 ± 20.73, p = 0.04).

CONCLUSIONS/SIGNIFICANCE

Our results demonstrate that chronic and heavy alcohol use in pregnancy impairs folate transport to the fetus. Altered folate concentrations within the placenta and in the fetus may in part contribute to the deficits observed in the fetal alcohol spectrum disorders.

Recognized spontaneous abortion in mid-pregnancy and patterns of pregnancy alcohol use

Alcohol consumption during pregnancy is one potential risk factor for spontaneous abortion (SAb). Prior research suggested that heavy drinking during pregnancy was associated with significantly increased rates of SAb, but results for lower levels of drinking have been inconsistent. We examined the association between different levels and patterns of prenatal alcohol consumption and SAb in a high-risk inner-city sample. We hypothesized that higher levels, binge patterns, and more frequent drinking would be associated with increased rates of SAb. The quantity and frequency of self-reported peri-conceptional and repeated in-pregnancy maternal drinking volumes per beverage type were assessed with semi-structured interviews in a prospective subsample of 302 African-American mothers. Relations between various measures of prenatal alcohol exposure and SAb were assessed using logistic regression. After controlling for various potential confounders, there was a significant positive relation between average absolute alcohol use per day across pregnancy and SAb. Greater frequency of drinking episodes also predicted SAb: an average of even one day of drinking per week across pregnancy was associated with an increase in the incidence of SAb. However, contrary to our hypothesis, neither the amount of alcohol drunk per drinking day nor a measure of binge drinking was significantly related to SAb after controlling for confounders. Differences in when women who drank at risk levels initiated antenatal care may have under-estimated the impact of alcohol on SAb in this low-SES urban African-American sample. Some drinking measures averaged across pregnancy may have under-estimated consumption and overestimated risk of SAb, but other risk drinking measures that avoid this limitation show similar relations to SAb. Identifying fetal risk drinking in pregnant women is critical to increasing the effectiveness of interventions that reduce risk level alcohol consumption and protect from pregnancy loss.

Folic acid fortification above mandated levels results in a low prevalence of folate inadequacy among Canadians

BACKGROUND

Understanding folate intakes after folic acid fortification of the food supply will help to establish dietary and supplement recommendations that balance health benefits and risks.

OBJECTIVES

The objectives were to estimate the prevalence of folate inadequacy (POFI) and intakes above the Tolerable Upper Intake Level (UL) among Canadians and to estimate the supplemental dose that, with diet, provides reproductive-aged women with 400 μg folic acid/d to prevent neural tube defects.

DESIGN

Twenty-four-hour recall and supplement (prior 30 d) data from the 2004 Canadian Community Health Survey (n = 35,107) were used to calculate the POFI and intakes above the UL with and without adjustment for fortification overages. POFI was also estimated by risk factors thought to be related to low folate intake. The Software for Intake Distribution Evaluation (SIDE program; Department of Statistics and Center for Agricultural and Rural Development, Iowa State University) was used to estimate usual dietary intakes in all analyses.

RESULTS

Except for women aged >70 y, POFI was <20% after adjustment for fortification overages. For children aged <14 y, POFI approached zero, even when supplement use was excluded. POFI among adults was unaffected by supplement use, except for women aged >70 y. Only 18% of reproductive-aged women consumed 400 μg folic acid/d from diet and supplements. Modeling showed that supplements containing 325-700 μg folic acid would provide adult women with 400 μg/d but not more than the UL. Diabetes was associated with POFI.

CONCLUSIONS

Innovative strategies are needed to ensure that the subgroups of Canadians who could still benefit from improved folate intake are targeted. Consideration should be given to removing folic acid from supplements designed for young children and men.

Meta- and pooled analyses of the methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism and colorectal cancer: a HuGE-GSEC review

Worldwide, over 1 million cases of colorectal cancer (CRC) were reported in 2002, with a 50% mortality rate, making CRC the second most common cancer in adults. Certain racial/ethnic populations continue to experience a disproportionate burden of CRC. A common polymorphism in the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene has been associated with a lower risk of CRC. The authors performed both a meta-analysis (29 studies; 11,936 cases, 18,714 controls) and a pooled analysis (14 studies; 5,068 cases, 7,876 controls) of the C677T MTHFR polymorphism and CRC, with stratification by racial/ethnic population and behavioral risk factors. There were few studies on different racial/ethnic populations. The overall meta-analysis odds ratio for CRC for persons with the TT genotype was 0.83 (95% confidence interval (CI): 0.77, 0.90). An inverse association was observed in whites (odds ratio = 0.83, 95% CI: 0.74, 0.94) and Asians (odds ratio = 0.80, 95% CI: 0.67, 0.96) but not in Latinos or blacks. Similar results were observed for Asians, Latinos, and blacks in the pooled analysis. The inverse association between the MTHFR 677TT polymorphism and CRC was not significantly modified by smoking status or body mass index; however, it was present in regular alcohol users only. The MTHFR 677TT polymorphism seems to be associated with a reduced risk of CRC, but this may not hold true for all populations.

Folate status in young overweight and obese women: changes associated with weight reduction and increased folate intake

OBJECTIVE

To analyze folate status changes in a group of overweight/obese young women following two different weight control programs.

METHODS

Fifty-seven women (BMI=24-35 kg/m(2)) were randomly assigned to one of two slightly hypocaloric diets: diet V, in which the consumption of vegetables was increased, or diet C, in which the consumption of cereals (especially breakfast cereals) was increased. Dietetic, anthropometric and biochemical data were collected at the start of the study and again at 6 wk.

RESULTS

At the beginning of the study, the obese women (BMI>or=30 kg/m(2)) were at greater risk of showing serum folic acid concentrations of <14.9 nmol/L, even though there were no differences in folate intake between them and the women with a lower BMI. Energy intake was reduced and folate intake increased with both the V and C diets. Weight was lost as a consequence of this lower energy intake. Serum folic acid concentration increased and the plasma homocysteine concentration diminished only in those who lost >2.5 kg; this was the case of the subjects as a whole and of those who followed the C diet. Among those who lost the most weight (>2.5 kg), the chances of having an increased serum folate concentration were higher, although no significant differences were seen in folate intake with respect to women who lost less weight.

CONCLUSIONS

Following a hypocaloric diet could lead to a better folate status through increased intake, but especially among those who lose the most body weight.

Combined effects of cigarette smoking and alcohol consumption on perinatal outcome

BACKGROUND

An increase in various congenital abnormalities associated with cigarette smoking and the use of alcohol during pregnancy has been reported in many studies. These exposures also increase the risk of pregnancy complications such as abruptio placentae, unexplained stillbirth, preterm labor and intrauterine growth restriction. However, very few studies have addressed the combined effect of smoking and drinking on pregnancy outcomes.

METHODS

In this review, the adverse effects of smoking or drinking on pregnancy were obtained from publications in which both substances were addressed in the same study population. A special effort was made to find studies in which the combined effect of these substances was investigated.

RESULTS

Preterm labor occurred more frequently in women who drank and smoked during pregnancy. This increased odds ratio was more than the sum of the effects of either smoking or drinking, indicating that the use of both substances by the same woman has a synergistic effect that increases the risk of preterm labor. This synergistic effect was also found for low birth weight and growth restriction.

CONCLUSIONS

As most of the women who drink during pregnancy also smoke cigarettes, attention should be given to the prevention or reduced use of both substances during pregnancy.

Comparison of blood folate levels among pregnant Chinese women in areas with high and low prevalence of neural tube defects

Objective

To characterise plasma and red-blood-cell (RBC) folate status among pregnant women in an area with an extremely high prevalence of neural tube defects, and to compare them with those of women from a low prevalence area.

Design

A cross-sectional survey conducted in 2003.

Setting

One county and one city from each of the high prevalence area and the low prevalence area in China.

Subjects

Five hundred and sixty-two women in their first trimester of pregnancy in the high prevalence area and 695 pregnant women in the low prevalence area.

Results

Women in the high prevalence area had less than half the plasma and RBC folate concentrations (12.2 and 440.0 nmol l− 1, respectively) of women in the low prevalence area (33.5 and 910.4 nmol l− 1, respectively). In the high prevalence area, 40% of rural women were deficient in RBC folate and 50% were deficient in plasma folate; 20% of urban women were deficient in RBC folate and 30% deficient in plasma folate. In contrast, only 4% (RBC folate) and 6% (plasma folate) of rural women, and 2% (RBC folate) and 1% (plasma folate) of urban women, were folate-deficient in the low prevalence area. Less than 10% of rural and about 26% of urban women in the high prevalence area took folic acid periconceptionally, compared with 70% and 60% of women in the low prevalence area.

Conclusions

Blood folate deficiency is highly prevalent among pregnant women in an area of China with a very high prevalence of neural tube defects.

Maternal smoking is associated with decreased 5-methyltetrahydrofolate in cord plasma

BACKGROUND

Maternal-fetal folate transport via the placenta has been shown to be concentrative. Exposure to cigarette smoke is associated with decreased maternal folate status through altered dietary intakes and possibly through nondietary mechanisms such as increased folate turnover. The effect of maternal smoking on fetal folate status has not been documented.

OBJECTIVE

The objective was to determine the effect of maternal smoking on plasma 5-methyltetrahydrofolic acid (5-MTHFA) concentrations in umbilical cord blood.

DESIGN

African American women were recruited from an antenatal clinic in Detroit, MI. Plasma 5-MTHFA concentrations were measured in maternal-umbilical cord pairings (n = 58). The participants completed a structured interview to determine demographic characteristics, including smoking.

RESULTS

Concentrations of 5-MTHFA were significantly higher in venous cord plasma (16.8 +/- 7.5 ng/mL) than in maternal plasma (13.0 +/- 7.5 ng/mL) but remained associated (r = 0.60, P < 0.001) with each other. Cigarettes smoked by the mothers was negatively associated (r = -0.31, P = 0.019) with venous cord 5-MTHFA concentrations and remained so after control for maternal plasma 5-MTHFA and other variables. Venous cord plasma 5-MTHFA was significantly lower in smoking (15.1 +/- 7.6 ng/mL; n = 32) than in nonsmoking (19.0 +/- 7.0 ng/mL; n = 26) mothers.

CONCLUSIONS

Cord plasma 5-MTHFA concentrations were elevated relative to maternal blood, as expected, because the placenta is capable of concentrative folate transport to the fetus. The negative effect of maternal smoking on infant, but not on maternal, 5-MTHFA status indicates that maternal smoking may impair folate transport to the fetus.

One-third of pregnant and lactating women may not be meeting their folate requirements from diet alone based on mandated levels of folic acid fortification

Many women are advised to consume a folic acid-containing prenatal supplement for the duration of pregnancy and lactation. Whether this remains necessary after folic acid fortification of the food supply in North America has yet to be determined. Our objective was to assess the dietary folate intake of a sample of pregnant and lactating women at mandated and predicted folic acid-fortification levels and determine the prevalence of inadequate and excessive intakes. Weighed food records (for 3 d) were collected from predominantly university-educated women (32 +/- 4 y of age) at 36 wk of pregnancy (n = 61) and at 4 and 16 wk of lactation (n = 60). Dietary folate intakes during pregnancy and lactation, assuming fortification at mandated levels (140-150 micro g/100 g), were 562 +/- 106 and 498 +/- 99 micro g/d dietary folate equivalents (DFE), respectively. The prevalence of inadequacy for folate, or the proportion of individuals with usual folate intakes less than their nutrient requirement, was 36% for women during pregnancy (estimated average requirement of 520 micro g/d DFE), and 32% during lactation (estimated average requirement of 450 micro g/d DFE). Assuming fortification at twice the mandated level, mean dietary intakes during pregnancy and lactation were 786 +/- 132 and 716 +/- 150 micro g/d DFE, respectively, producing only a 3% prevalence of folate inadequacy. Grains contributed approximately 41% of total folate intake followed by fruits and vegetables (approximately 21%). To conclude, at mandated levels of fortification many pregnant and lactating women are unlikely to meet their folate requirements from dietary sources alone; however, the actual level of inadequacy cannot be determined until the level of folic acid in the food supply is known with greater precision.

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.

Iron deficiency anemia and depleted body iron reserves are prevalent among pregnant African-American adolescents

Anemia is prevalent among pregnant adolescents, but few data exist on biochemical indicators of iron status in this group. We hypothesized that among an at-risk population of African-American, pregnant adolescents, the degree of iron depletion and deficiency would be marked, and that iron deficiency anemia would comprise the majority of the observed anemia. To examine this, blood samples were collected from 80 girls (< or =18 y old) attending an inner city maternity clinic, 23 of whom were studied longitudinally in the 2nd and 3rd trimesters depending on contact at the clinic. Sample sizes for the biomarkers varied according to the blood volume available at the time the assays were completed. Descriptive statistics were applied to characterize iron status, and multivariate regression and logistic analyses were used to identify significant determinants of iron status. Depleted iron stores (ferritin < or = 15 microg/L) were indicated for 25% (n = 44) and 61% (n = 59) of adolescents during the 2nd and 3rd trimesters, respectively. Serum folate (39.3 +/- 15.4 nmol/L, n = 60), RBC folate (2378 +/- 971 nmol/L, n = 60), and serum vitamin B-12 concentrations (313 +/- 163 pmol/L, n = 60) were within normal ranges. Adolescents with serum transferrin receptor:serum ferritin ratios (R:F ratio) > 300 during the 2nd trimester were 12.5 times (95% CI 2.83, 55.25) more likely to be classified with iron deficiency anemia during the 3rd trimester (P = 0.0002) than those with lower ratios. Estimates of body iron were lower in those tested after wk 26 of gestation (P < 0.0001), and reserves were depleted in 5.0% vs. 31.3% of the 2nd (n = 40) and 3rd (n = 48) trimester cohorts, respectively. In conclusion, iron-deficiency anemia was prevalent among these pregnant minority adolescents. Targeted screening and interventions to improve diet and compliance with prenatal iron supplementation are warranted for this at-risk group.