The prevention of megaloblastic anaemia in pregnancy in Nigeria

Effects of Maternal Nutritional Supplements and Dietary Interventions on Placental Complications: An Umbrella Review, Meta-Analysis and Evidence Map

The placenta is a vital, multi-functional organ that acts as an interface between maternal and fetal circulation during pregnancy. Nutritional deficiencies during pregnancy alter placental development and function, leading to adverse pregnancy outcomes, such as pre-eclampsia, infants with small for gestational age and low birthweight, preterm birth, stillbirths and maternal mortality. Maternal nutritional supplementation may help to mitigate the risks, but the evidence base is difficult to navigate. The primary purpose of this umbrella review is to map the evidence on the effects of maternal nutritional supplements and dietary interventions on pregnancy outcomes related to placental disorders and maternal mortality. A systematic search was performed on seven electronic databases, the PROSPERO register and references lists of identified papers. The results were screened in a three-stage process based on title, abstract and full-text by two independent reviewers. Randomized controlled trial meta-analyses on the efficacy of maternal nutritional supplements or dietary interventions were included. There were 91 meta-analyses included, covering 23 types of supplements and three types of dietary interventions. We found evidence that supports supplementary vitamin D and/or calcium, omega-3, multiple micronutrients, lipid-based nutrients, and balanced protein energy in reducing the risks of adverse maternal and fetal health outcomes. However, these findings are limited by poor quality of evidence. Nutrient combinations show promise and support a paradigm shift to maternal dietary balance, rather than single micronutrient deficiencies, to improve maternal and fetal health. The review is registered at PROSPERO (CRD42020160887).

Folic Acid Metabolism and Malaria

Folate is essential for DNA synthesis and the survival and growth of the malaria parasite. Folate sufficiency may be associated with an increased risk of malaria. Antifolate antimalarial drugs are of major importance in the prophylaxis and treatment of malaria. Folic acid reverses the inhibition by antifolate drugs of plasmodial growth or survival in vitro, and folic acid supplements given to children with malaria may increase the failure rate of treatment with antimalarials. There is no convincing evidence of a significant prevalence of folate deficiency in children in malarious areas, nor of a beneficial effect of folic acid supplementation on malarial anemia. In areas where Plasmodium falciparum malaria is holoendemic, universal supplementation of children with iron and folic acid may increase the incidence of severe morbidity and mortality. These regions should be excluded from the World Health Organization recommendation of universal folic acid supplementation of children in areas of high prevalence of anemia. This does not apply to supplementation of pregnant women with folic acid.

Effect of folic acid supplementation on preterm delivery and small for gestational age births: A systematic review and meta-analysis

OBJECTIVE

To investigate the effect of folic acid (FA) supplementation on the risks of preterm delivery (PTD) and small for gestational age births (SGA).

DATA SOURCES

Cohort studies were identified from MEDLINE, EMBASE, the Cochrane Library, CINAHL, and CBM from inception to January 2015.

PARTICIPANTS AND INCLUDED STUDIES

Healthy women who want to get pregnancy or being pregnant.

MAIN OUTCOME MEASURES

PTD and SGA.

RESULTS

The association of FA and PTD was significant when supplement initiated after pregnancy (RR=0.68, 95%CI, 0.52-0.90), whereas no effect was founded if the initiation time was before conception (RR=0.89, 95%CI, 0.80-1.01). The results for the association between FA supplementation and SGA showed significant protective effect: initiated before conception (RR=0.70, 95%CI, 0.57-0.85) and initiated after conception (RR=0.84, 95%CI, 0.81-0.89).

CONCLUSION

Folic acid supplementation is associated with a significant reduction on the risk of PTD when initiated after conception. It can also protect fetus from SGA.

Vitamin supplementation for preventing miscarriage

BACKGROUND

Miscarriage is a common complication of pregnancy that can be caused by a wide range of factors. Poor dietary intake of vitamins has been associated with an increased risk of miscarriage, therefore supplementing women with vitamins either prior to or in early pregnancy may help prevent miscarriage.

OBJECTIVES

The objectives of this review were to determine the effectiveness and safety of any vitamin supplementation, on the risk of spontaneous miscarriage.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group Trials Register (6 November 2015) and reference lists of retrieved studies.

SELECTION CRITERIA

All randomised and quasi-randomised trials comparing supplementation during pregnancy with one or more vitamins with either placebo, other vitamins, no vitamins or other interventions. We have included supplementation that started prior to conception, periconceptionally or in early pregnancy (less than 20 weeks' gestation).

DATA COLLECTION AND ANALYSIS

Three review authors independently assessed trials for inclusion, extracted data and assessed trial quality. We assessed the quality of the evidence using the GRADE approach. The quality of evidence is included for numerical results of outcomes included in the 'Summary of findings' tables.

MAIN RESULTS

We included a total of 40 trials (involving 276,820 women and 278,413 pregnancies) assessing supplementation with any vitamin(s) starting prior to 20 weeks' gestation and reporting at least one primary outcome that was eligible for the review. Eight trials were cluster-randomised and contributed data for 217,726 women and 219,267 pregnancies in total.Approximately half of the included trials were assessed to have a low risk of bias for both random sequence generation and adequate concealment of participants to treatment and control groups. Vitamin C supplementation There was no difference in the risk of total fetal loss (risk ratio (RR) 1.14, 95% confidence interval (CI) 0.92 to 1.40, seven trials, 18,949 women; high-quality evidence); early or late miscarriage (RR 0.90, 95% CI 0.65 to 1.26, four trials, 13,346 women; moderate-quality evidence); stillbirth (RR 1.31, 95% CI 0.97 to 1.76, seven trials, 21,442 women; moderate-quality evidence) or adverse effects of vitamin supplementation (RR 1.16, 95% CI 0.39 to 3.41, one trial, 739 women; moderate-quality evidence) between women receiving vitamin C with vitamin E compared with placebo or no vitamin C groups. No clear differences were seen in the risk of total fetal loss or miscarriage between women receiving any other combination of vitamin C compared with placebo or no vitamin C groups. Vitamin A supplementation No difference was found in the risk of total fetal loss (RR 1.01, 95% CI 0.61 to 1.66, three trials, 1640 women; low-quality evidence); early or late miscarriage (RR 0.86, 95% CI 0.46 to 1.62, two trials, 1397 women; low-quality evidence) or stillbirth (RR 1.29, 95% CI 0.57 to 2.91, three trials, 1640 women; low-quality evidence) between women receiving vitamin A plus iron and folate compared with placebo or no vitamin A groups. There was no evidence of differences in the risk of total fetal loss or miscarriage between women receiving any other combination of vitamin A compared with placebo or no vitamin A groups. Multivitamin supplementation There was evidence of a decrease in the risk for stillbirth among women receiving multivitamins plus iron and folic acid compared iron and folate only groups (RR 0.92, 95% CI 0.85 to 0.99, 10 trials, 79,851 women; high-quality evidence). Although total fetal loss was lower in women who were given multivitamins without folic acid (RR 0.49, 95% CI 0.34 to 0.70, one trial, 907 women); and multivitamins with or without vitamin A (RR 0.60, 95% CI 0.39 to 0.92, one trial, 1074 women), these findings included one trial each with small numbers of women involved. Also, they include studies where the comparison groups included women receiving either vitamin A or placebo, and thus require caution in interpretation.We found no difference in the risk of total fetal loss (RR 0.96, 95% CI 0.93 to 1.00, 10 trials, 94,948 women; high-quality evidence) or early or late miscarriage (RR 0.98, 95% CI 0.94 to 1.03, 10 trials, 94,948 women; moderate-quality evidence) between women receiving multivitamins plus iron and folic acid compared with iron and folate only groups.There was no evidence of differences in the risk of total fetal loss or miscarriage between women receiving any other combination of multivitamins compared with placebo, folic acid or vitamin A groups. Folic acid supplementation There was no evidence of any difference in the risk of total fetal loss, early or late miscarriage, stillbirth or congenital malformations between women supplemented with folic acid with or without multivitamins and/or iron compared with no folic acid groups. Antioxidant vitamins supplementation There was no evidence of differences in early or late miscarriage between women given antioxidant compared with the low antioxidant group (RR 1.12, 95% CI 0.24 to 5.29, one trial, 110 women).

AUTHORS' CONCLUSIONS

Taking any vitamin supplements prior to pregnancy or in early pregnancy does not prevent women experiencing miscarriage. However, evidence showed that women receiving multivitamins plus iron and folic acid had reduced risk for stillbirth. There is insufficient evidence to examine the effects of different combinations of vitamins on miscarriage and miscarriage-related outcomes.

Folic acid supplementation in pregnancy to prevent preterm birth: a systematic review and meta-analysis of randomized controlled trials

Folic acid (FA) may have a role in the prevention of pregnancy complications. However, the efficacy of FA supplementation in reducing the risk of preterm birth (PTB) is still unclear. The aim of this systematic review with meta-analysis was to evaluate the efficacy of folic acid supplementation during pregnancy to prevent preterm birth (PTB). The research protocol was designed a priori, defining methods for searching the literature in electronic databases, including and examining articles, and extracting and analyzing data. We included all randomized trials (RCTs) of asymptomatic singleton gestations without prior PTB who were randomized to prophylactic treatment with either FA supplementation or control (placebo or no treatment). The primary outcome was the incidence of PTB <37 weeks. Five randomized trials including 5,332 asymptomatic singleton gestations without prior PTB were included in the analysis. Women who received FA supplementation had a similar rate of PTB <37 weeks (22.6% vs 22.9%; RR 0.99, 95% CI 0.82-1.18), PTB<34 weeks (7.1% vs 8.7%; RR 0.77, 95% CI 0.55-1.09) and of preterm premature rupture of membranes (2.4% vs 2.9%; RR 0.81, 95% CI 0.44-1.50) compared with control group. Regarding neonatal outcome we found no significant differences in birth weight (mean difference 85.58g, 95% CI -55.17-226.34), low birth weight (21.0% vs 15.1%; RR 0.79, 95% CI 0.49 to 1.28) and perinatal death (2.9% vs 2.4%; RR 0.90, 95% CI 0.60-1.34). In summary, FA supplementation during pregnancy does not prevent PTB <37 weeks. Daily FA supplementation remains the most important intervention to reduce the risk of neural tube defects.

Maternal folate status, but not that of vitamins B-12 or B-6, is associated with gestational age and preterm birth risk in a multiethnic Asian population

BACKGROUND

Maternal folate, vitamin B-12, and vitamin B-6 concentrations during pregnancy have been shown to influence birth outcomes, but the evidence is inconclusive.

OBJECTIVE

We aimed to examine the associations of maternal B-vitamin status with gestational age, birth weight, and length in a birth cohort study in Singapore.

METHODS

Maternal blood samples (n = 999) collected during weeks 26-28 of gestation were assayed for plasma folate, vitamin B-12, and vitamin B-6 concentrations. Birth weight and gestational age data were obtained from hospital records, and other anthropometric variables were measured within 72 h after birth. Relations between B-vitamin status and birth outcomes were assessed by linear or logistic regression with adjustment for potential confounders.

RESULTS

Median (IQR) plasma concentrations were 34.4 (24.5-44.6) nmol/L for folate, 209 (167-258) pmol/L for vitamin B-12, and 61.8 (25.9-113) nmol/L for vitamin B-6. We found that higher plasma folate concentrations were associated with a longer gestational age (0.12 wk per SD increase in folate; 95% CI: 0.02, 0.21) and tended to be associated with lower risk of all preterm birth (delivery at <37 wk of gestation; OR: 0.79; 95% CI: 0.63, 1.00) and spontaneous preterm birth (OR: 0.76; 95% CI: 0.56, 1.04). Overall, concentrations of maternal folate, vitamin B-12, and vitamin B-6 were not independently associated with birth weight or being born small for gestational age (SGA; birth weight <10th percentile for gestational age).

CONCLUSIONS

Higher maternal folate concentrations during late pregnancy were associated with longer gestational age and tended to be associated with a lower risk of preterm birth in this multiethnic Asian population. In contrast, the results of our study suggested little or no benefit of higher folate concentrations for reducing the risk of SGA or of higher vitamin B-6 and vitamin B-12 concentrations for reducing the risk of preterm birth or SGA.

Folic acid supplementation and preterm birth: results from observational studies

INTRODUCTION

Folic acid (FA) supplementation is recommended worldwide in the periconceptional period for the prevention of neural tube defects. Due to its involvement in a number of cellular processes, its role in other pregnancy outcomes such as miscarriage, recurrent miscarriage, low birth weight, preterm birth (PTB), preeclampsia, abruptio placentae, and stillbirth has been investigated. PTB is a leading cause of perinatal mortality and morbidity; therefore its association with FA supplementation is of major interest. The analysis of a small number of randomized clinical trials (RCTs) has not found a beneficial role of FA in reducing the rate of PTBs.

AIM OF THE STUDY

The aim of this review was to examine the results from recent observational studies about the effect of FA supplementation on PTB.

MATERIALS AND METHODS

We carried out a search on Medline and by manual search of the observational studies from 2009 onwards that analyzed the rate of PTB in patients who received supplementation with FA before and/or throughout pregnancy.

RESULTS

The results from recent observational studies suggest a slight reduction of PTBs that is not consistent with the results from RCTs. Further research is needed to better understand the role of FA supplementation before and during pregnancy in PTB.

Effect of folic acid supplementation in pregnancy on preeclampsia: the folic acid clinical trial study

Preeclampsia (PE) is hypertension with proteinuria that develops during pregnancy and affects at least 5% of pregnancies. The Effect of Folic Acid Supplementation in Pregnancy on Preeclampsia: the Folic Acid Clinical Trial (FACT) aims to recruit 3,656 high risk women to evaluate a new prevention strategy for PE: supplementation of folic acid throughout pregnancy. Pregnant women with increased risk of developing PE presenting to a trial participating center between 8^0/7 and 16^6/7 weeks of gestation are randomized in a 1 : 1 ratio to folic acid 4.0 mg or placebo after written consent is obtained. Intent-to-treat population will be analyzed. The FACT study was funded by the Canadian Institutes of Health Research in 2009, and regulatory approval from Health Canada was obtained in 2010. A web-based randomization system and electronic data collection system provide the platform for participating centers to randomize their eligible participants and enter data in real time. To date we have twenty participating Canadian centers, of which eighteen are actively recruiting, and seven participating Australian centers, of which two are actively recruiting. Recruitment in Argentina, UK, Netherlands, Brazil, West Indies, and United States is expected to begin by the second or third quarter of 2013. This trial is registered with NCT01355159.

Folic acid supplementation during pregnancy for maternal health and pregnancy outcomes

BACKGROUND

During pregnancy, fetal growth causes an increase in the total number of rapidly dividing cells, which leads to increased requirements for folate. Inadequate folate intake leads to a decrease in serum folate concentration, resulting in a decrease in erythrocyte folate concentration, a rise in homocysteine concentration, and megaloblastic changes in the bone marrow and other tissues with rapidly dividing cells

OBJECTIVES

To assess the effectiveness of oral folic acid supplementation alone or with other micronutrients versus no folic acid (placebo or same micronutrients but no folic acid) during pregnancy on haematological and biochemical parameters during pregnancy and on pregnancy outcomes.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 December 2012) and we contacted major organisations working in micronutrient supplementation, including UNICEF Nutrition Section, World Health Organization (WHO) Maternal and Reproductive Health, WHO Nutrition Division, and National Center on Birth defects and Developmnetal Disabilities, US Centers for Disease Control and Prevention (CDC).

SELECTION CRITERIA

All randomised, cluster-randomised and cross-over controlled trials evaluating supplementation of folic acid alone or with other micronutrients versus no folic acid (placebo or same micronutrients but no folic acid) in pregnancy.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion, assessed risk of bias and extracted data. Data were checked for accuracy.

MAIN RESULTS

Thirty-one trials involving 17,771 women are included in this review. This review found that folic acid supplementation has no impact on pregnancy outcomes such as preterm birth (risk ratio (RR) 1.01, 95% confidence interval (CI) 0.73 to 1.38; three studies, 2959 participants), and stillbirths/neonatal deaths (RR 1.33, 95% CI 0.96 to 1.85; three studies, 3110 participants). However, improvements were seen in the mean birthweight (mean difference (MD) 135.75, 95% CI 47.85 to 223.68). On the other hand, the review found no impact on improving pre-delivery anaemia (average RR 0.62, 95% CI 0.35 to 1.10; eight studies, 4149 participants; random-effects), mean pre-delivery haemoglobin level (MD -0.03, 95% CI -0.25 to 0.19; 12 studies, 1806 participants), mean pre-delivery serum folate levels (standardised mean difference (SMD) 2.03, 95% CI 0.80 to 3.27; eight studies, 1250 participants; random-effects), and mean pre-delivery red cell folate levels (SMD 1.59, 95% CI -0.07 to 3.26; four studies, 427 participants; random-effects). However, a significant reduction was seen in the incidence of megaloblastic anaemia (RR 0.21, 95% CI 0.11 to 0.38, four studies, 3839 participants).

AUTHORS' CONCLUSIONS

We found no conclusive evidence of benefit of folic acid supplementation during pregnancy on pregnancy outcomes.

Vitamin supplementation for preventing miscarriage

BACKGROUND

Miscarriage is a common complication of pregnancy that can be caused by a wide range of factors. Poor dietary intake of vitamins has been associated with an increased risk of miscarriage, therefore supplementing women with vitamins either prior to or in early pregnancy may help prevent miscarriage.

OBJECTIVES

The objectives of this review are to determine the effectiveness and safety of any vitamin supplementation, on the risk of spontaneous miscarriage, maternal adverse outcomes and fetal and infant adverse outcomes.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group Trials Register (21 June 2010).

SELECTION CRITERIA

All randomised and quasi-randomised trials comparing one or more vitamins with either placebo, other vitamins, no vitamins or other interventions, prior to conception, periconceptionally or in early pregnancy (less than 20 weeks' gestation).

DATA COLLECTION AND ANALYSIS

At least two review authors independently assessed trials for inclusion, extracted data and assessed trial quality.

MAIN RESULTS

We identified 28 trials assessing supplementation with any vitamin(s) starting prior to 20 weeks' gestation and reporting at least one primary outcome that was eligible for the review. Overall, the included trials involved 96,674 women and 98,267 pregnancies. Three trials were cluster randomised and combined contributed data for 62,669 women and 64,210 pregnancies in total. No significant differences were seen between women taking any vitamins compared with controls for total fetal loss (relative risk (RR) 1.04, 95% confidence interval (CI) 0.95 to 1.14), early or late miscarriage (RR 1.09, 95% CI 0.95 to 1.25) or stillbirth (RR 0.86, 95% CI 0.65 to 1.13) and most of the other primary outcomes, using fixed-effect models. Compared with controls, women given any type of vitamin(s) pre or peri-conception were more likely to have a multiple pregnancy (RR 1.38, 95% CI 1.12 to 1.70, three trials, 20,986 women).

AUTHORS' CONCLUSIONS

Taking any vitamin supplements prior to pregnancy or in early pregnancy does not prevent women experiencing miscarriage or stillbirth. However, women taking vitamin supplements may be more likely to have a multiple pregnancy. There is insufficient evidence to examine the effects of different combinations of vitamins on miscarriage, stillbirth or other maternal and infant outcomes.

The treatment of iron-deficiency anaemia with a new intramuscular iron preparation (Ferastral)

The treatment of iron-deficiency anaemia in pregnancy with a new intramuscular iron preparation, iron-poly (sorbitol-gluconic acid) complex (Ferastral), has been assessed and compared with oral iron therapy. Sixty-one of the eighty-four patients studied, many of whom had mild to moderate degree of anaemia were treated with Ferastral. The results were satisfactory, the mean increase of haematocrit at the sixth post treatment week was 28.7% for the whole series. Complete correction of anaemia was achieved in most patients between the 4th and 6th week of treatment. The mean haematocrit of the group treated with oral iron was initially significantly higher than for the group treated with Ferastral. At the first follow-up, two weeks after beginning treatment, the mean values for both groups were similar; at four weeks, those receiving Ferastral had a significantly higher mean PCV than those on oral iron, and remained so through the period of observation. No side-effects were detected using 10 ml of Ferastral intramuscularly on alternate days. The mean hospitalization time of patients with severe to moderate anaemia was reduced when given parenteral therapy, and the frequency of blood transfusion in these patients was also decreased.

A High Prevalence of Biochemical Evidence of Vitamin B12 or Folate Deficiency does not Translate into a Comparable Prevalence of Anemia

Based on biochemical evidence, a high prevalence of biochemical evidence of vitamin B12 or folate deficiency has been reported in a number of areas in the world. The evidence that these biochemical abnormalities lead to a comparable prevalence of anemia is reviewed. The overall contribution of vitamin B12 deficiency to the global burden of anemia is probably not significant, except perhaps in women and their infants and children in vegetarian communities. In developed countries, folate-deficiency anemia is uncommon. In some developing countries, this anemia is still seen, but there are no comprehensive data on the relative prevalence compared with anemia due to malaria, iron-deficiency, hemoglobinopathy, and HIV disease. It seems unlikely that folate deficiency makes a major contribution to the burden of anemia in developing countries. Iron-deficiency anemia may coexist with vitamin B12 and especially folate deficiency, and may confound the hematological features of the vitamin deficiencies whose prevalence would then be underestimated. Supplementation of the diet of pregnant women with folic acid can virtually eliminate folate-deficiency anemia in these women. There are very few data on the hematological effect of vitamin B12 supplementation or fortification at the population level. The addition of vitamin B12 to the supplementation of the diet of pregnant women with iron and folic acid does not produce an increased hematological response, at least in nonvegetarian populations. There are numerous reports of the effect of folic acid fortification of food on tests of folate status, but only a single published report on the hematological response was found.

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

The essentiality of folate and vitamin B12 for the synthesis of DNA may interfere with a successful pregnancy outcome when the mother is deficient in these micronutrients. The objective of this paper is to assess the effects of folate and vitamin B12 deficiencies on pregnancy outcomes, other than neural tube defects (NTD), and the effects of these deficiencies on infant and child development.

Supplementation studies identified by two Cochran Reviews were selected to assess the impact of folate deficiency on pregnancy outcomes, and a systematic review of the literature was used to assess their effects on infant and child developments.

Folate supplementation consistently resulted in improvement of hematological and folate status indicators. Seven supplemental studies consistently found no differences in the risk of total fetal loss, early or late miscarriage, stillbirth, preeclampsia, perinatal death, neonatal death, preterm birth, small-for-gestational age, or infant death in supplemented women compared with their controls. Two of those studies found greater placental weights (difference 96 g; 95% CI, 30.7 to 161.2 g), birthweights (difference 312 g; 95% CI, 108.5 to 515.4 g), and a lower risk for newborns weighing < 2,500 g in supplemented women (RR = 0.94; 95% CI, 0.90 to 0.99). Abnormal vitamin B12 and homocysteine serum concentrations were more readily associated with poor pregnancy outcomes. The very few studies addressing the effects of folate and vitamin B12 deficiencies on infant and child development were inconclusive.

Early supplementation with folate to pregnant women improves hematological and folate status indicators, but has little or no effect on pregnancy outcomes, other than on NTD. Vitamin B12 deficiencies and low homocysteine are more readily associated with poor pregnancy outcomes.

WITHDRAWN: Folate supplementation in pregnancy

BACKGROUND

Folate depletion may result in anaemia during pregnancy.

OBJECTIVES

The objective of this review was to assess the effects of folate supplementation in pregnancy on haematological and biochemical parameters and measures of pregnancy outcome. This review did not address the role of periconceptual folate supplementation to diminish the risk of fetal malformation.

SEARCH STRATEGY

A comprehensive electronic search included that of the Cochrane Pregnancy and Childbirth Group trials register. Date of last search: October 2001.

SELECTION CRITERIA

Acceptably controlled trials of folate supplementation compared with placebo or no treatment to pregnant women with normal haemoglobin levels.

DATA COLLECTION AND ANALYSIS

Trial quality was assessed. Study authors were contacted for additional information when necessary.

MAIN RESULTS

Twenty-one studies were included. The trials varied in quality. Compared to placebo or no supplementation, folate supplementation was associated with increased or maintained serum folate levels (odds ratio 0.18, 95% confidence interval 0.13 to 0.24) and red cell folate levels (odds ratio 0.18, 95% confidence interval 0.09 to 0.38). Folate supplementation was associated with a reduction in the proportion of women with low haemoglobin level in late pregnancy (odds ratio 0.61, 95% confidence interval 0.52 to 0.71) and megaloblastic erythropoiesis (odds ratio 0.65, 95% confidence interval 0.45 to 0.95). Apart from a possible reduction in the incidence of low birthweight, folate supplementation appears to have no measurable effect on any other substantive measures of pregnancy outcome.

AUTHORS' CONCLUSIONS

Folate supplementation during pregnancy appears to improve haemoglobin levels and folate status. There is not enough evidence to evaluate whether folate supplementation has any effect, beneficial or harmful, on clinical outcomes for mother and baby.

The role of placental oxidative stress and lipid peroxidation in preeclampsia

Preeclampsia is a complex multisystem disorder exclusively seen in human species that is characterized by hypertension and proteinuria. This disorder has the highest maternal and fetal morbidity and mortality of all pregnancy-related complications. Growing evidence suggests that placental oxidative stress is involved in the etiopathogenesis of preeclampsia. Reduced perfusion as a result of abnormal placentation leads to ischemia reperfusion injury to the placenta. Placental oxidative stress, which results from the ischemia reperfusion injury, is being increasingly reported to be involved in the etiopathogenesis of preeclampsia. It has been proposed as a promoter of lipid peroxidation and the endothelial cell dysfunction that is commonly seen in this condition. Although preeclampsia is characterized by increased lipid peroxidation and diminished antioxidant capacity, there is no consensus regarding causality of lipid peroxidation in preeclampsia. In this article, we address the question of the biologic association of lipid peroxidation and preeclampsia. Lipid peroxidation and leukocyte activation may play a pivotal role in endothelial cell dysfunction. We also review the different factors that have been proposed to cause endothelial cell dysfunction in preeclampsia, trials investigating the role of antioxidant supplementation in preeclampsia, and the lack of consensus among the trials. Additional longitudinal studies are necessary to determine if the various oxidative stress biomarkers estimated early in pregnancy can be narrowed to a single marker for predicting preeclampsia.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader should be able to recall that placental oxidative stress is involved in the etiopathogenesis of preeclampsia, state that placental oxidative stress results from ischemic reperfusion injury, and explain that ischemic reperfusion injury is a promoter of lipid peroxidation and endothelial cell dysfunction seen in preeclampsia.

Vitamin supplementation for preventing miscarriage

BACKGROUND

Miscarriage is a common complication of pregnancy that can be caused by a wide range of factors. Poor dietary intake of vitamins has been associated with an increased risk of miscarriage, therefore supplementing women with vitamins either prior to or in early pregnancy may help prevent miscarriage.

OBJECTIVES

The objectives of this review are to determine the effectiveness and safety of any vitamin supplementation, on the risk of spontaneous miscarriage, maternal adverse outcomes and fetal and infant adverse outcomes.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group Trials Register (8 September 2004), the Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 2, 2003) and MEDLINE (1966 to May 2003), Current Contents (1998 to May 2003) and EMBASE (1980 to May 2003).

SELECTION CRITERIA

All randomised and quasi-randomised trials comparing one or more vitamins with either placebo, other vitamins, no vitamins or other interventions, prior to conception, periconceptionally or in early pregnancy (less than 20 weeks' gestation).

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion, extracted data and assessed trial quality.

MAIN RESULTS

We identified seventeen trials assessing supplementation with any vitamin(s) starting prior to 20 weeks' gestation and reporting at least one primary outcome that were eligible for the review. Overall, the included trials involved 35,812 women and 37,353 pregnancies. Two trials were cluster randomised and contributed data for 20,758 women and 22,299 pregnancies in total. No difference was seen between women taking any vitamins compared with controls for total fetal loss (relative risk (RR) 1.05, 95% confidence interval (CI) 0.95 to 1.15), early or late miscarriage (RR 1.08, 95% CI 0.95 to 1.24) or stillbirth (RR 0.85, 95% CI 0.63 to 1.14) and most of the other primary outcomes, using fixed-effect models. For the other primary outcomes, women given any type of vitamin(s) compared with controls were less likely to develop pre-eclampsia (RR 0.68, 95% CI 0.54 to 0.85, four trials, 5580 women) and more likely to have a multiple pregnancy (RR 1.38, 95% CI 1.12 to 1.70, three trials, 20,986 women).

AUTHORS' CONCLUSIONS

Taking vitamin supplements, alone or in combination with other vitamins, prior to pregnancy or in early pregnancy, does not prevent women experiencing miscarriage or stillbirth. However, women taking vitamin supplements may be less likely to develop pre-eclampsia and more likely to have a multiple pregnancy.

Is There a Causal Relationship between Iron Deficiency or Iron-Deficiency Anemia and Weight at Birth, Length of Gestation and Perinatal Mortality?

An extensive literature review was conducted to identify whether iron deficiency, iron-deficiency anemia and anemia from any cause are causally related to low birth weight, preterm birth or perinatal mortality. Strong evidence exists for an association between maternal hemoglobin concentration and birth weight as well as between maternal hemoglobin concentration and preterm birth. It was not possible to determine how much of this association is attributable to iron-deficiency anemia in particular. Minimal values for both low birth weight and preterm birth occurred at maternal hemoglobin concentrations below the current cut-off value for anemia during pregnancy (110 g/L) in a number of studies, particularly those in which maternal hemoglobin values were not controlled for the duration of gestation. Supplementation of anemic or nonanemic pregnant women with iron, folic acid or both does not appear to increase either birth weight or the duration of gestation. However, these studies must be interpreted cautiously because most are subject to a bias toward false-negative findings. Thus, although there may be other reasons to offer women supplemental iron during pregnancy, the currently available evidence from studies with designs appropriate to establish a causal relationship is insufficient to support or reject this practice for the specific purposes of raising birth weight or lowering the rate of preterm birth.

Nutritional modulation of malaria morbidity and mortality

This review critically examines the relationship between nutritional status and malaria. The data indicate that protein-energy malnutrition is associated with greater malaria morbidity and mortality in humans. In addition, controlled trials of either vitamin A or zinc supplementation show that these nutrients can substantially reduce clinical malaria attacks. Data for iron indicate that supplementation may minimally aggravate certain malariometric indices in some settings and also strongly improve hematologic status. Withholding of iron supplements from deficient population is, therefore, not currently indicated. Available evidence for other nutrients describe varied effects, with some deficiencies being exacerbative (e.g., thiamine), protective (e.g., vitamin E), or both exacerbative and protective in different settings (e.g., riboflavin, vitamin C). The roles of folate, other B vitamins, unsaturated fatty acids, amino acids, and selenium are also examined. Study of the interactions between nutrition and malaria may provide insight to protective mechanisms and result in nutrient-based interventions as low-cost and effective adjuncts to current methods of malaria prevention and treatment.

Folate supplementation in pregnancy

BACKGROUND

Folate depletion may result in anaemia during pregnancy.

OBJECTIVES

The objective of this review was to assess the effects of folate supplementation in pregnancy on haematological and biochemical parameters and measures of pregnancy outcome. This review did not address the role of periconceptual folate supplementation to diminish the risk of fetal malformation.

SEARCH STRATEGY

A comprehensive electronic search included that of the Cochrane Pregnancy and Childbirth Group trials register.

SELECTION CRITERIA

Acceptably controlled trials of folate supplementation compared with placebo or no treatment to pregnant women with normal haemoglobin levels.

DATA COLLECTION AND ANALYSIS

Trial quality was assessed. Study authors were contacted for additional information when necessary.

MAIN RESULTS

Twenty-one studies were included. The trials varied in quality. Compared to placebo or no supplementation, folate supplementation was associated with increased or maintained serum folate levels (odds ratio 0.18, 95% confidence interval 0.13 to 0.24) and red cell folate levels (odds ratio 0.18, 95% confidence interval 0.09 to 0.38). Folate supplementation was associated with a reduction in the proportion of women with low haemoglobin level in late pregnancy (odds ratio 0.61, 95% confidence interval 0.52 to 0.71) and megaloblastic erythropoiesis (odds ratio 0.65, 95% confidence interval 0.45 to 0.95). Apart from a possible reduction in the incidence of low birthweight, folate supplementation appears to have no measurable effect on any other substantive measures of pregnancy outcome.

REVIEWER'S CONCLUSIONS

Folate supplementation during pregnancy appears to improve haemoglobin levels and folate status. There is not enough evidence to evaluate whether folate supplementation has any effect, beneficial or harmful, on clinical outcomes for mother and baby.

Nutritional interventions for the prevention of maternal morbidity

OBJECTIVE

To review the effectiveness of nutritional interventions to prevent maternal morbidity.

METHODS

This is an overview of systematic reviews and individual randomized controlled trials (if no systematic review available) of nutritional interventions during pregnancy. For each nutrient intervention the main maternal morbidity data reported were extracted. These were pre-eclampsia/eclampsia, pregnancy-induced hypertension, hemorrhage, anemia, infection and obstructed labor. In addition, the trial settings, the number of trials and participants' characteristics were systematically extracted.

RESULTS

The systematic reviews considered in this paper had only few trials that reported the selected maternal outcomes. Outcome measures are based sometimes on one trial only. Most of the interventions compared single micronutrient supplementation with placebo/no treatment and did not show significant benefits for the supplementation groups. Calcium supplementation in women at high risk of pregnancy hypertension reduced the incidence of high blood pressure (RR, 0.35; 95% CI, 0.21-0.57) and pre-eclampsia (RR, 0.22; 95% CI, 0.11-0.43). Similarly, in women with low dietary calcium intake, calcium supplementation resulted in a significant reduction in the incidence of high blood pressure (RR, 0.49; 95% CI, 0.38-0.62) and pre-eclampsia (RR, 0.32; CI, 0.21-0.49). In women at low risk of pregnancy hypertension or with adequate baseline calcium intake, the beneficial effects of calcium supplementation are small and unlikely to be of clinical significance. Both, iron and folate supplementation reduced the number of women with low pre-delivery hemoglobin.

CONCLUSIONS

Routine calcium supplementation seems to be a promising intervention for pregnant women at risk of developing preeclampsia or have low calcium intake, but these findings need to be confirmed with a trial with adequate power in different settings. In populations with high incidence of nutritional anemia routine iron and folate supplementation should be recommended during ante-natal care. It is unclear at this stage if adding vitamin A to iron and folate supplementation in anemia prevalent areas provides further benefits. There is inadequate data on the benefits or harms of routine iron or folate supplementation in adequately nourished populations. With regard to other micronutrient supplementation, such as zinc, magnesium and fish oil, randomized controlled trials with sufficient power to detect clinically important differences in maternal and infant outcomes are needed.

The safety of antimalarial drugs in pregnancy

Alternative drugs to chloroquine are required to prevent the deleterious effects of malaria in pregnancy. Fear of potential toxicity has limited antimalarial drug use in pregnancy. Animal toxicity studies have documented teratogenicity when antimalarials are administered at high dosages. Excepting the tetracyclines, there is no evidence to suggest that, at standard dosages, any of the antimalarial drugs are teratogenic. Primaquine is not recommended because of the potential risk of haemolytic effects in the fetus. Rates of spontaneous abortion and birth defects were comparable in pregnant women taking mefloquine, compared with chloroquine-proguanil, or pyrimethamine-sulfadoxine prophylaxis, in the first trimester of pregnancy. Standard doses of quinine do not increase the risk of abortion or preterm delivery. Therapeutic mefloquine does not provoke hypoglycaemia. There is no evidence in the literature to support the hypothetical risk of kernicterus in the newborn, following exposure to antimalarial drugs containing sulphonamides or sulphones prior to delivery. Documentation of the safety of doxycycline, halofantrine, and the artemisinin derivatives in the treatment of malaria in pregnant women is currently limited.

The effects of malaria chemoprophylaxis given by traditional birth attendants on the course and outcome of pregnancy

A trial of malaria chemoprophylaxis given by traditional birth attendants was undertaken in a rural area of The Gambia where access to antenatal clinics is difficult. Women received one or more doses of Maloprim or placebo from a traditional birth attendant during 1049 of 1208 pregnancies (87%) recorded in 16 villages over a 3-year period. Primigravidae who received Maloprim had a lower parasite rate and a significantly higher mean packed cell volume than primigravidae who received placebo, and their babies were significantly heavier (6% low birth weight vs 22%). In multigravidae chemoprophylaxis reduced malaria parasitaemia but it had no beneficial effect on haemoglobin level and much less effect on birth weight than was observed in primigravidae. However, the mean birth weight of babies born to grandemultigravidae who received chemoprophylaxis was significantly higher than that of babies born to grandemultigravidae who did not.

Tropical obstetrics and gynaecology. 1. Anaemia in pregnancy in tropical Africa

Major causes of anaemia in pregnancy in tropical Africa are malaria, iron deficiency, folate deficiency and haemoglobinopathies: now there is added also the acquired immune deficiency syndrome (AIDS). Anaemia is often multifactorial, with the different causes interacting in a vicious cycle of depressed immunity, infection and malnutrition. Anaemia progresses through 3 stages: compensation, with breathlessness on exertion only; decompensation, with breathlessness at rest and haemoglobin (Hb) below about 70 g/litre; cardiac failure, with Hb below about 40 g/litre. Without treatment, over half of the women with haematocrit less than 0.13 and heart failure die. Maternal anaemia, malaria and deficiencies of iron and folate cause intrauterine growth retardation, premature delivery and, when severe, perinatal mortality. Surviving infants have low birthweights, immune deficiency and poor reserves of iron and folate. They have entered already the vicious cycle of infection, malnutrition and impaired immunity. Treatment with blood transfusions is even more hazardous since the advent of AIDS, and should be limited to saving the life of the mother. Treatment of malaria is complex as chloroquine-resistant strains are now common. Prevention remains relatively easy with proguanil and supplements of iron and folic acid and is highly cost-effective in the improvement of maternal and infant health; it is more important than ever as it avoids the unnecessary exposure of women and infants to HIV transmitted through blood transfusion.

Abruptio placentae at the University of Nigeria Teaching Hospital, Enugu: a 3-year study

A total of 81 cases of abruptio placentae treated in a 3-year period at the University of Nigeria Teaching Hospital, Enugu is reported. The incidence of 0.44% found in the study is low when compared to reports from Europe. The outstanding clinical features were high parity, low incidence of renal failure, hypertension and proteinuria. The perinatal mortality of 58% is quite high while 2 mothers who were referred to the Teaching Hospital in poor condition died. Management was by rapid and adequate resuscitation by blood transfusion and delivery as soon as the diagnosis was made. The absence of maternal mortality amongst mothers who received antenatal care at the University Teaching Hospital emphasizes the need for adequate antenatal and intrapartum care in order to eliminate the complications of this obstetrical enigma.

The aetiology of severe anaemia in pregnancy in Ndola, Zambia

The aetiology of severe anaemia (haemoglobin less than 7.0 g dl-1) has been studied in 37 pregnant Zambians. Aetiology was usually multiple; 31 (84%) had Plasmodium falciparum malaria, 23 (62%) were folate deficient, 13 (35%) were iron deficient, one had sickle-cell anaemia and one had the acquired immunodeficiency syndrome (AIDS). Folate deficiency was most often secondary to malarial haemolysis: iron deficiency was nutritional, but hookworm was contributory in about one-third of patients. The anaemia of malaria and folate deficiency was both more common and more severe than anaemia due to iron deficiency; it was seen in younger women although primigravidae were not over-represented, it occurred earlier in pregnancy, and was associated with low birthweight. AIDS must now be included in the differential diagnosis of anaemia in pregnancy. Vigorous antimalarial treatment and prophylaxis are essential in the management and prevention of anaemia in pregnancy. Total dose iron infusion is indicated only when severe iron deficiency anaemia has been proven, and must be accompanied by antimalarial therapy and folic acid supplements. Because of the risk of transmission of human immunodeficiency virus, it is more important than ever to prevent anaemia and malaria in pregnancy, and to give blood transfusion only as a life-saving treatment.

The prevention of anaemia in pregnancy in primigravidae in the guinea savanna of Nigeria

Two hundred Hausa primigravidae at Zaria were divided into five groups in a randomized double-blind trial of antenatal oral antimalarial prophylaxis, and haematinic supplements. Group 1 received no active treatment. Groups 2 to 5 were given chloroquine 600 mg base once, followed by proguanil 100 mg per day. In addition, group 3 received iron 60 mg daily, group 4 folic acid 1 mg daily, and group 5 iron plus folic acid. Forty-five percent were anaemic (haemoglobin (Hb) less than 11.0 g dl-1) at first attendance before 24 weeks of gestation, and malaria parasitaemia (predominantly Plasmodium falciparum) was seen in 27%, of whom 60% were anaemic. The mean Hb fell during pregnancy in group 1, and seven patients in this group had to be removed from the trial and treated for severe anaemia (packed cell volume (PCV) less than 0.26). Only five patients in the other groups developed severe anaemia (P = 0.006), two of whom had malaria following failure to take treatment. Patients in group 1 had the lowest mean Hb at 28 and 36 weeks of gestation, and patients receiving antimalarials and iron (groups 3 and 5) had the highest Hb at 28 weeks, but differences were not significant, possibly due to removal from the trial of patients with severe anaemia. Anaemia (Hb less than 12.0 g dl-1) at six weeks after delivery was observed in 61% of those not receiving active treatment (group 1), in 39% of those protected against malaria but not receiving iron supplements (groups 2 and 4) and in only 18% of patients receiving both antimalarials and iron (groups 3 and 5). Folic acid had no significant effect on mean Hb. Proguanil was confirmed to be a highly effective causal prophylaxis. Prevention of malaria, without folic acid supplements, reduced the frequency of megaloblastic erythropoiesis from 56% to 25%. Folic acid supplements abolished megaloblastosis, except in three patients who were apparently not taking the treatment prescribed. Red cell folate (RCF) concentrations were higher in subjects with malaria, probably due to intracellular synthesis by plasmodia. Infants of mothers not receiving antimalarials appeared to have an erythroid hyperplasia. Maternal folate supplements raised infants' serum folate and RCF. Fourteen per cent had low birth weight (less than 2500 g), and the perinatal death rate was 11%; the greatest number were in group 1, but not significantly. A regime is proposed for the prevention of malaria, iron deficiency, folate deficiency and anaemia in pregnancy in the guinea savanna of Nigeria.

Anaemia in young primigravidae in the guinea savanna of Nigeria: sickle-cell trait gives partial protection against malaria

Haematological indices, malarial parasitaemia, serum and red cell folate (SFA, RCF), serum vitamin B12 and haemoglobin (Hb) electrophoretic patterns were studied in 228 non-elite young Hausa primigravidae at less than 24 weeks of gestation. The study was conducted in the guinea savanna of Nigeria, where malaria is hyperendemic. Ninety-nine (43%) were anaemic (Hb less than 11.0 g dl-1). The commonest cause of anaemia was malaria, in 28% of all and 40% of anaemic subjects. Plasmodium falciparum was predominant; P. malariae was seen in 1.3% and P. ovale was not recorded. Parasitaemia was more frequent and more dense in the wet than the dry season. Iron deficiency was diagnosed in 18% of all and 25% of anaemic women; 14% of all patients were folate-deficient; high MCV and MCH correlated with anaemia, and low SFA was associated weakly with anaemia and malaria. Serum vitamin B12 was normal or high in all 145 in whom it was measured; 3% had congenital elliptocytosis, but this did not contribute to the anaemia. Sickle-cell trait was present in 26% and Hb-AC in less than 1%. Hb-AS was associated with significantly lower frequency and density of P. falciparum; this has not been demonstrated in pregnancy in Africa previously. However, the parasitological advantage was not reflected in any haematological advantage. The roles of malaria, folate-deficiency and iron-deficiency in the causation of anaemia in Hausa primigravidae will be defined further by a double-blind trial of antimalarial prophylactics, iron supplements and folic acid supplements.

Dietary iron intake of pregnant Nigerian women with anemia

The daily dietary iron intake of nine pregnant Nigerian women with confirmed iron deficiency anemia was determined. The daily dietary iron intake from hospital meals served to ten other pregnant women was also assessed to serve as a control. The mean daily iron intake of the group of anemic patients on home diet was 14.6 mg (range of individual means = 8.37-25.28 mg), whereas the group of patients served hospital meals had a mean daily dietary iron intake of 36.92 mg (range of individual means = 25.09-46.47 mg). It is, therefore, clear that the etiology of iron deficiency in the patients studied was mainly dietary. Thus, our pregnant patients, many of whom are on diets similar to those of the group studied, should receive iron supplements during pregnancy.

Iron deficiency anaemia in a rural area in Nigeria. Evaluation of diagnosis and treatment with imferon

In 32 pregnant women with packed cell volume (PCV) of 30% or less (Hb 10 g/100 ml or below), iron depletion was present in 87.5% and megaloblastic changes in 84.5% as judged by bone marrow findings. Parenteral iron gave statistically significant rise in the PCV (p less than 0.001) in those who received iron therapy compared with control group with no iron therapy. Routine iron administration during pregnancy is therefore indicated in this population.

Iron deficiency anaemia in Nigerian pregnant women

Ninety-four Nigerian pregnant women, many of who had mild to moderate anaemia, were investigated for the presence of iron deficiency. Using the bone marrow as the diagnostic index, 90% of these patients were found to be iron deficient. Iron deficiency is thus common among our expectant mothers. They should, therefore, be given iron supplement in addition to the present practice of folic acid and antimalarials, throughout pregnancy and the puerperium.

Folic acid deficiency in the United States: folate assays in a prenatal clinic

Tissue deficiency of folic acid, as measured by a red cell folate level below 150 ng. per milliliter, was present in 16 per cent of 110 sequential pregnant women at the time of their first prenatal visit to a municipal clinic. A further 14 per cent of subjects had red cell folate levels in the range "suggestive but not conclusive for tissue folate depletion" (150 to 199 ng. per milliliter). All of the subjects were from low-income families in New York City and most were black or of Puerto Rican origin. Serum folate levels showed good general correlation with red cell folate but were of less value as a diagnostic test, since they were below the lower limit of normal in 64 per cent of subjects, including many subjects who did not yet have low tissue folate. In contrast to their value in other folate deficiency states, neutrophil lobe counts showed no correlation with serum or red cell folate levels in pregnancy and thus appeared of little diagnostic value in pregnancy. It is suggested that surveys of folate deficiency in other pregnant population groups in the United States be carried out. These results support the recommendations of the Committee on Maternal Nutrition and the Committee on Dietary Allowances of the Food and Nutrition Board, National Research Council (U.S.A.) that folic acid supplements (200 to 400 mug per day) should be taken throughout pregnancy.

Severe haemolytic anaemia in pregnancy in Nigerians treated with prednisolone

Haemolytic anaemia of obscure aetiology is a common complication of pregnancy in Nigeria. Treatment with antimalarials and folic acid is usually followed by a rapid remission, but response is slow in about 25% of patients and haemolysis continues uncontrolled in about 5%. The administration of prednisolone to six patients with uncontrolled haemolysis was followed by rapid recovery in five and possible benefit in one. Risks of prednisolone therapy to the mother appear to be slight and outweighed by the risks of continued severe anaemia and frequent blood transfusions. There seemed to be no appreciable increase of fetal loss compared with that in anaemic pregnancies not treated with prednisolone.