Vitamins C and E in the latency period in women with preterm premature rupture of membranes

The relationship between the latency period, infection markers, and oxidant and antioxidant states in women with preterm premature rupture of membranes

BACKGROUND

A major cause of perinatal morbidity and mortality has been reported to be preterm premature rupture of membranes (PPROM). Our objective was to evaluate oxidant-antioxidant balance, infection parameters, time interval between rupture of membranes and delivery (latency period), and the relationship among all these parameters.

METHODS

Seventy-five cases with PPROM between 24 and 34 gestational weeks were included in the study. A control group of 41 women who gave birth at term were considered as the control group. The relationship among maternal plasma total oxidative stress (TOS), malondialdehyde (MDA), total antioxidant status (TAS), leukocyte counts, CRP, vitamin C and E levels, gestational week, neonatal birthweight, and latency period was evaluated.

RESULTS

In cases with PPROM, rupture occurred at an average of 29.4 gestational weeks and premature babies were born at an average of 31.6 gestational weeks. The mortality rate of babies born to PPROM women was 18.7% (14/75) died at or following birth. In the PPROM group, TOS, MDA, and leukocyte counts were found to be significantly higher compared to the control group (p < 0.001). Besides, a significant negative correlation was detected among the latency period, TOS, CRP, and leukocyte counts (p < 0.05).

CONCLUSIONS

Appropriate treatment protocols that strengthen antioxidant defense systems and taking into consideration the signs of infection can decrease the incidence of PPROM and/or mortality rates of babies born to PPROM women.

Low Serum Vitamin C Status Among Pregnant Women Attending Antenatal Care at General Hospital Dawakin Kudu, Northwest Nigeria

Background:

Vitamin C levels are low in pregnancy. The purpose of this study was to determine serum Vitamins C levels among pregnant women attending antenatal care at a General Hospital in Dawakin Kudu, Kano, and this can help further research to determine the place of Vitamin C supplementation in pregnancy.

Methods:

This was a prospective study of 400 pregnant women who presented for antenatal care in General Hospital Dawakin Kudu, Kano, Nigeria. Research structured questionnaire was administered to 400 respondents. Determination of serum Vitamin C was done using appropriate biochemical methods.

Results:

Vitamin C deficiency was found in 79.5% of the participants. The values for Vitamin C were 0.20 ± 0.18 mg/dl during the first trimester, 0.50 ± 0.99 mg/dl in the second trimester, and 0.35 ± 0.36 mg/dl in the third trimester and P = 0.001.

Conclusions:

There is a significant reduction in the serum Vitamins C concentration throughout the period of pregnancy with the highest levels in the second trimester. Therefore, Vitamin C supplementation is suggested during pregnancy, especially for those whose fruit and vegetable consumption is inadequate.

Vitamin C supplementation in pregnancy

BACKGROUND

Vitamin C supplementation may help reduce the risk of pregnancy complications such as pre-eclampsia, intrauterine growth restriction and maternal anaemia. There is a need to evaluate the efficacy and safety of vitamin C supplementation in pregnancy.

OBJECTIVES

To evaluate the effects of vitamin C supplementation, alone or in combination with other separate supplements on pregnancy outcomes, adverse events, side effects and use of health resources.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 March 2015) and reference lists of retrieved studies.

SELECTION CRITERIA

All randomised or quasi-randomised controlled trials evaluating vitamin C supplementation in pregnant women. Interventions using a multivitamin supplement containing vitamin C or where the primary supplement was iron were excluded.

DATA COLLECTION AND ANALYSIS

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

MAIN RESULTS

Twenty-nine trials involving 24,300 women are included in this review. Overall, 11 trials were judged to be of low risk of bias, eight were high risk of bias and for 10 trials it was unclear. No clear differences were seen between women supplemented with vitamin C alone or in combination with other supplements compared with placebo or no control for the risk of stillbirth (risk ratio (RR) 1.15, 95% confidence intervals (CI) 0.89 to 1.49; 20,038 participants; 11 studies; I² = 0%; moderate quality evidence), neonatal death (RR 0.79, 95% CI 0.58 to 1.08; 19,575 participants; 11 studies; I² = 0%), perinatal death (average RR 1.07, 95% CI 0.77 to 1.49; 17,105 participants; seven studies; I² = 35%), birthweight (mean difference (MD) 26.88 g, 95% CI -18.81 to 72.58; 17,326 participants; 13 studies; I² = 69%), intrauterine growth restriction (RR 0.98, 95% CI 0.91 to 1.06; 20,361 participants; 12 studies; I² = 15%; high quality evidence), preterm birth (average RR 0.99, 95% CI 0.90 to 1.10; 22,250 participants; 16 studies; I² = 49%; high quality evidence), preterm PROM (prelabour rupture of membranes) (average RR 0.98, 95% CI 0.70 to 1.36; 16,825 participants; 10 studies; I² = 70%; low quality evidence), term PROM (average RR 1.26, 95% CI 0.62 to 2.56; 2674 participants; three studies; I² = 87%), and clinical pre-eclampsia (average RR 0.92, 95% CI 0.80 to 1.05; 21,956 participants; 16 studies; I² = 41%; high quality evidence).Women supplemented with vitamin C alone or in combination with other supplements compared with placebo or no control were at decreased risk of having a placental abruption (RR 0.64, 95% CI 0.44 to 0.92; 15,755 participants; eight studies; I² = 0%; high quality evidence) and had a small increase in gestational age at birth (MD 0.31, 95% CI 0.01 to 0.61; 14,062 participants; nine studies; I² = 65%), however they were also more likely to self-report abdominal pain (RR 1.66, 95% CI 1.16 to 2.37; 1877 participants; one study). In the subgroup analyses based on the type of supplement, vitamin C supplementation alone was associated with a reduced risk of preterm PROM (average RR 0.66, 95% CI 0.48 to 0.91; 1282 participants; five studies; I² = 0%) and term PROM (average RR 0.55, 95% CI 0.32 to 0.94; 170 participants; one study). Conversely, the risk of term PROM was increased when supplementation included vitamin C and vitamin E (average RR 1.73, 95% CI 1.34 to 2.23; 3060 participants; two studies; I² = 0%). There were no differences in the effects of vitamin C on other outcomes in the subgroup analyses examining the type of supplement. There were no differing patterns in other subgroups of women based on underlying risk of pregnancy complications, timing of commencement of supplementation or dietary intake of vitamin C prior to trial entry. The GRADE quality of the evidence was high for intrauterine growth restriction, preterm birth, and placental abruption, moderate for stillbirth and clinical pre-eclampsia, low for preterm PROM.

AUTHORS' CONCLUSIONS

The data do not support routine vitamin C supplementation alone or in combination with other supplements for the prevention of fetal or neonatal death, poor fetal growth, preterm birth or pre-eclampsia. Further research is required to elucidate the possible role of vitamin C in the prevention of placental abruption and prelabour rupture of membranes. There was no convincing evidence that vitamin C supplementation alone or in combination with other supplements results in other important benefits or harms.

Vitamin E supplementation in pregnancy

BACKGROUND

Vitamin E supplementation may help reduce the risk of pregnancy complications involving oxidative stress, such as pre-eclampsia. There is a need to evaluate the efficacy and safety of vitamin E supplementation in pregnancy.

OBJECTIVES

To assess the effects of vitamin E supplementation, alone or in combination with other separate supplements, on pregnancy outcomes, adverse events, side effects and use of health services.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 March 2015) and reference lists of retrieved studies.

SELECTION CRITERIA

All randomised or quasi-randomised controlled trials evaluating vitamin E supplementation in pregnant women. We excluded interventions using a multivitamin supplement that contained vitamin E.

DATA COLLECTION AND ANALYSIS

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

MAIN RESULTS

Twenty-one trials, involving 22,129 women were eligible for this review. Four trials did not contribute data. All of the remaining 17 trials assessed vitamin E in combination with vitamin C and/or other agents. Overall the risk of bias ranged from low to unclear to high; 10 trials were judged to be at low risk of bias, six trials to be at unclear risk of bias and five trials to be at high risk of bias. No clear difference was found between women supplemented with vitamin E in combination with other supplements during pregnancy compared with placebo for the risk of stillbirth (risk ratio (RR) 1.17, 95% confidence interval (CI) 0.88 to 1.56, nine studies, 19,023 participants, I² = 0%; moderate quality evidence), neonatal death (RR 0.81, 95% CI 0.58 to 1.13, nine trials, 18,617 participants, I² = 0%), pre-eclampsia (average RR 0.91, 95% CI 0.79 to 1.06; 14 trials, 20,878 participants; I² = 48%; moderate quality evidence), preterm birth (average RR 0.98, 95% CI 0.88 to 1.09, 11 trials, 20,565 participants, I² = 52%; high quality evidence) or intrauterine growth restriction (RR 0.98, 95% CI 0.91 to 1.06, 11 trials, 20,202 participants, I² = 17%; high quality evidence). Women supplemented with vitamin E in combination with other supplements compared with placebo were at decreased risk of having a placental abruption (RR 0.64, 95% CI 0.44 to 0.93, seven trials, 14,922 participants, I² = 0%; high quality evidence). Conversely, supplementation with vitamin E was associated with an increased risk of self-reported abdominal pain (RR 1.66, 95% CI 1.16 to 2.37, one trial, 1877 participants) and term prelabour rupture of membranes (PROM) (average RR 1.77, 95% CI 1.37 to 2.28, two trials, 2504 participants, I² = 0%); however, there was no corresponding increased risk for preterm PROM (average RR 1.27, 95% CI 0.93 to 1.75, five trials, 1999 participants, I² = 66%; low quality evidence). There were no clear differences between the vitamin E and placebo or control groups for any other maternal or infant outcomes. There were no clear differing patterns in subgroups of women based on the timing of commencement of supplementation or baseline risk of adverse pregnancy outcomes. The GRADE quality of the evidence was high for preterm birth, intrauterine growth restriction and placental abruption, moderate for stillbirth and clinical pre-eclampsia, and low for preterm PROM.

AUTHORS' CONCLUSIONS

The data do not support routine vitamin E supplementation in combination with other supplements for the prevention of stillbirth, neonatal death, preterm birth, pre-eclampsia, preterm or term PROM or poor fetal growth. Further research is required to elucidate the possible role of vitamin E in the prevention of placental abruption. There was no convincing evidence that vitamin E supplementation in combination with other supplements results in other important benefits or harms.

Vitamins A and E Deficiencies among Pregnant Women Attending Antenatal Care at General Hospital Dawakin Kudu, North-West Nigeria

Background:

Vitamins A and E deficiency is prevalent in developing countries, and plasma levels are low in pregnancy. This study was undertaken to determine the serum Vitamins A and E status among pregnant women attending antenatal care at a General Hospital in Dawakin Kudu, Kano and to provide the necessary information needed to suggest the supplementation of Vitamins A and E during pregnancy.

Methods:

The study was done in General Hospital Dawakin Kudu Local Government Area. Dawakin Kudu, a rural community in Kano State is about 12 km from Kano metropolis which is the most populous city in Nigeria and commercial nerve center of Northern Nigeria. Most of the women are housewives, however, some engage in subsistent farming and petty trading. This was a prospective study of 200 pregnant women at various maternal ages, gestational ages, and parities. Informed consent was obtained from the participants. Research structured questionnaire was administered to 200 respondents which showed age and parity distributions. Determination of Serum Vitamins A and E was done using methods of Bessey, et al. and Tsen. Ethical approval for the research was obtained from General Hospital, Dawakin Kudu, Kano. Statistical Analysis Used: Data obtained were analyzed using SPSS version 17 statistical software (SPSS Inc., IL, Chicago, USA). Descriptive statistics was done. Mean serum Vitamins A and E concentration between trimesters were compared using two-way ANOVA and P < 0.05 was considered statistically significant.

Results:

Majority of the women were aged 20–39 years with mean of 23.67 ± 6.11. Most were in the 1–4 parity range. Mean birth weight was 2.42 ± 0.74 kg. Above 65% were deficient while 34.5% had normal levels of Vitamin A and 51% were deficient of serum Vitamin E. Serum Vitamins A and E levels showed a marked reduction from first through third trimester. The differences were statistically significant (P < 0.05).

Conclusions:

There is a significant reduction in the serum Vitamins A and E concentration throughout the period of pregnancy with the highest levels in the first trimester. Therefore, further studies should evaluate the value of Vitamins A and E supplementation during pregnancy especially for those whose fruit and vegetable consumption is inadequate.

The Effects of Intravenous Hydration on Amniotic Fluid Index in Pregnant Women with Preterm premature Rupture of Membranes: A Randomized Clinical Trial

INTRODUCTION

Preterm premature rupture of membranes (PPROM) can result in fetal complications such as oligohydramnios. This study aimed to determine the effects of intravenous (IV) fluid bolus on amniotic fluid index (AFI) in pregnant women with PPROM.

METHODS

24 women with PPROM during singleton live pregnancy of 28 to 34 weeks whose baseline AFI was ≤ 5cm were randomized into two groups. The study group received one liter intravenous fluid bolus of isotonic Ringer serum during 30-minute period. Reevaluations of amniotic fluid index in both groups were made 90 minutes and 48 hours after baseline measurement. Independent t-test and paired t-test were used to compare the two groups and mean amniotic fluid index before and after treatment, respectively.

RESULTS

The results of this study demonstrate that AFI decreased statistically significant in both the control and study groups. AFI decreased in both groups at 48 hours later. This decrease was not statistically significant in any group. The mean change in AFI (90 minutes and baseline) and (48 hours and baseline) between the two groups were not significant. The time between mean baseline measurements and delivery were 196.41 and 140.58 hours in the study and control groups, respectively. This difference was not statistically significant.

CONCLUSION

This study did not find significant impact of hydration On AFI as a prophylactic method on oligohydramnios in pregnant women with PPROM.

Transabdominal amnioinfusion for preterm premature rupture of membranes: a systematic review and metaanalysis of randomized and observational studies

OBJECTIVE

The purpose of this study was to review systematically the efficacy of transabdominal amnioinfusion (TA) in early preterm premature rupture of membranes (PPROM).

STUDY DESIGN

We conducted a literature search of EMBASE, MEDLINE, and ClinicalTrials.gov databases and identified studies in which TA was used in cases of proven PPROM and oligohydramnios. Risk of bias was assessed for observational studies and randomized controlled trials. Primary outcomes were latency period and perinatal mortality rates.

RESULTS

Four observational studies (n = 147) and 3 randomized controlled trials (n = 165) were eligible. Pooled latency period was 14.4 (range, 8.2-20.6) and 11.41 (range -3.4 to 26.2) days longer in the TA group in the observational and the randomized controlled trials, respectively. Perinatal mortality rates were reduced among the treatment groups in both the observational studies (odds ratio, 0.12; 95% confidence interval, 0.02-0.61) and the randomized controlled trials (odds ratio, 0.33; 95% confidence interval, 0.10-1.12).

CONCLUSION

Serial TA for early PPROM may improve early PPROM-associated morbidity and mortality rates. Additional adequately powered randomized control trials are needed.

Polymorphism of haptoglobin in patients with premature rupture of membrane

PURPOSE

To investigate whether allelic polymorphism of haptoglobin (Hp) is associated with premature rupture of membrane (PROM), the Hp phenotypes of pregnant women with PROM were analyzed.

PATIENTS AND METHODS

The Hp phenotypes of 221 pregnant Korean women (187 control and 34 PROM patients) were determined by benzidine/hydrogen peroxide staining, following native polyacrylamide gel electrophoresis of hemoglobin-mixed sera. The Hp allele frequencies were calculated from the data of Hp phenotypes, and overall association with PROM was evaluated using Pearson Chi-Square test.

RESULTS

The polymorphic distribution of the patients cohort who underwent a normal delivery (control group) was similar to that of healthy Koreans. In contrast, however, patients with PROM showed significantly higher occurrence of the Hp 1-1 phenotype than control group (23.5% vs 8.0%). Hp 2-2 phenotype was lower in PROM cohort (38.2%) than in the control group (48.7%). The Hp(1) allele frequency in PROM group was significantly higher than that in the control group (0.426 vs 0.297, p = 0.034) with odds ratio of 1.762 (95% CI: 1.038 - 2.991).

CONCLUSION

These findings suggest that pregnant Korean women who possess Hp(1) allele (expressed as Hp 1-1 phenotype) have higher incidence of PROM than women with Hp(2) allele (expressed as Hp 2-2 phenotype). This is the first study that evaluated the significance of Hp polymorphism with respect to the development of PROM.

Antioxidants for preventing pre-eclampsia

BACKGROUND

Oxidative stress has been proposed as a key factor involved in the development of pre-eclampsia. Supplementing women with antioxidants during pregnancy may help to counteract oxidative stress and thereby prevent or delay the onset of pre-eclampsia.

OBJECTIVES

To determine the effectiveness and safety of any antioxidant supplementation during pregnancy and the risk of developing pre-eclampsia and its related complications.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (May 2007), the Cochrane Central Register of Controlled Trials (The Cochrane Library 2006, Issue 3), MEDLINE (1950 to October 2007) and Current Contents (1998 to August 2004).

SELECTION CRITERIA

All randomised trials comparing one or more antioxidants with either placebo or no antioxidants during pregnancy for the prevention of pre-eclampsia, and trials comparing one or more antioxidants with another, or with other interventions.

DATA COLLECTION AND ANALYSIS

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

MAIN RESULTS

Ten trials, involving 6533 women, were included in this review, five trials were rated high quality. For the majority of trials, the antioxidant assessed was combined vitamin C and E therapy. There was no significant difference between antioxidant and control groups for the relative risk (RR) of pre-eclampsia (RR 0.73, 95% confidence intervals (CI) 0.51 to 1.06; nine trials, 5446 women) or any other primary outcome: severe pre-eclampsia (RR 1.25, 95% CI 0.89 to 1.76; two trials, 2495 women), preterm birth (before 37 weeks) (RR 1.10, 95% CI 0.99 to 1.22; five trials, 5198 women), small-for-gestational-age infants (RR 0.83, 95% CI 0.62 to 1.11; five trials, 5271 babies) or any baby death (RR 1.12, 95% CI 0.81 to 1.53; four trials, 5144 babies). Women allocated antioxidants were more likely to self-report abdominal pain late in pregnancy (RR 1.61, 95% CI 1.11 to 2.34; one trial, 1745 women), require antihypertensive therapy (RR 1.77, 95% CI 1.22 to 2.57; two trials, 4272 women) and require an antenatal hospital admission for hypertension (RR 1.54, 95% CI 1.00 to 2.39; one trial, 1877 women). However, for the latter two outcomes, this was not clearly reflected in an increase in any other hypertensive complications.

AUTHORS' CONCLUSIONS

Evidence from this review does not support routine antioxidant supplementation during pregnancy to reduce the risk of pre-eclampsia and other serious complications in pregnancy.

Association between oxidative stress in pregnancy and preterm premature rupture of membranes

BACKGROUND

Premature rupture of membranes (PROM) is caused by collagen damage in the chorioamniotic sac leading to tearing. Reactive oxygen species (ROS) may be the cause of collagen damage. Isoprostanes (F(2)-IP) are produced by ROS attack on polyunsaturated fatty acids and are sensitive and specific biomarkers of lipid-peroxidation in vivo.

AIM

To verify whether oxidative stress occurs in pregnancies associated with preterm PROM.

METHODS

F(2)-IPs were measured in amniotic fluid of 16 pregnancies with preterm PROM (Group II) and 97 without PROM (Group I).

RESULTS

F(2)-IP concentrations (pg/mL) were significantly higher in group II than group I (p<0.0001). The ROC curve showed a sensitivity of 100% and a specificity of 84.5% at a cut-off of 124.4 pg/mL.

CONCLUSIONS

An association exists between oxidative stress in pregnancy and preterm PROM. The detection of amniotic fluid F(2)-IP concentrations seems to be a reliable predictive index of risk of preterm PROM.

Nutritional supplements in pregnancy: commercial push or evidence based?

PURPOSE OF REVIEW

This review examines whether nutritional supplements during pregnancy have a role to play in the health of the mother, outcome of pregnancy or health of the baby. It will put into context the increased use of nutritional supplements in pregnancy and whether there is an evidence base for this supplementation.

RECENT FINDINGS

Women are not consuming enough nutrients from their diet alone and food is depleted in many important minerals. There is increasing support that supplementation of specific vitamins, minerals and omega-3 fatty acids can have a positive impact on maternal health in terms of prevention of preeclampsia, miscarriage, preterm birth, low birthweight, gestational diabetes and also on the long-term health of the baby. There are some contradictory findings with antioxidants and prevention of preeclampsia, and these are discussed.

SUMMARY

With soil depletion, overfarming and transportation of foods over hundreds of miles with loss of nutrients en route, together with the increased use of convenience and fast foods, women can be over-fed, but under-nourished in our modern society. These can lead to nutrient deficiencies which can have an impact on the outcome of pregnancy. Evidence shows that supplementation can play a valuable role in the health of the pregnant mother and her baby. Emphasis must always be on eating a good diet, but given the limitations of the 21st century lifestyle and the nutritional content of food, good quality nutritional supplements should be used during pregnancy in combinations rather than isolated single nutrients.

Vitamin E supplementation in pregnancy

BACKGROUND

Vitamin E supplementation may help reduce the risk of pregnancy complications involving oxidative stress, such as pre-eclampsia. There is a need to evaluate the efficacy and safety of vitamin E supplementation in pregnancy.

OBJECTIVES

To assess the effects of vitamin E supplementation, alone or in combination with other separate supplements, on pregnancy outcomes, adverse events, side-effects and use of health services.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group Trials Register (23 June 2004), the Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 2, 2004), MEDLINE (1966 to May 2004), Current Contents (1998 to May 2004) and EMBASE (1980 to May 2004).

SELECTION CRITERIA

All randomised or quasi-randomised controlled trials evaluating vitamin E supplementation in pregnant women. We excluded interventions using a multivitamin supplement that contained vitamin E.

DATA COLLECTION AND ANALYSIS

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

MAIN RESULTS

Four trials, involving 566 women either at high risk of pre-eclampsia or with established pre-eclampsia, were eligible for this review. All trials assessed vitamin E in combination with other supplements and two trials were published in abstract form only. No difference was found between women supplemented with vitamin E in combination with other supplements during pregnancy compared with placebo for the risk of stillbirth (relative risk (RR) was 0.77, 95% confidence intervals (CI) 0.35 to 1.71, two trials, 339 women), neonatal death (RR 5.00, 95% CI 0.64 to 39.06, one trial, 40 women), perinatal death (RR 1.29, 95% CI 0.67 to 2.48, one trial, 56 women), preterm birth (RR 1.29, 95% CI 0.78 to 2.15, two trials, 383 women), intrauterine growth restriction (RR 0.72, 95% CI 0.49 to 1.04, two trials, 383 women) or birthweight (weighted mean difference -139.00 g, 95% CI -517.68 to 239.68, one trial, 100 women), using fixed-effect models. Substantial heterogeneity was found for pre-eclampsia. Women supplemented with vitamin E in combination with other supplements compared with placebo were at decreased risk of developing clinical pre-eclampsia (RR 0.44, 95% CI 0.27 to 0.71, three trials, 510 women) using fixed-effect models; however, this difference could not be demonstrated when using random-effects models (RR 0.44, 95% CI 0.16 to 1.22, three trials, 510 women). There were no differences between women supplemented with vitamin E compared with placebo for any of the secondary outcomes.

AUTHORS' CONCLUSIONS

The data are too few to say if vitamin E supplementation either alone or in combination with other supplements is beneficial during pregnancy.

Vitamin C supplementation in pregnancy

BACKGROUND

Vitamin C supplementation may help reduce the risk of pregnancy complications like pre-eclampsia, intrauterine growth restriction and maternal anaemia. There is a need to evaluate the efficacy and safety of vitamin C supplementation in pregnancy.

OBJECTIVES

To evaluate the effects of vitamin C supplementation, alone or in combination with other separate supplements, on pregnancy outcomes, adverse events, side-effects and use of health resources.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group Trials Register (23 June 2004), Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 2, 2004), MEDLINE, Current Contents and EMBASE.

SELECTION CRITERIA

All randomised or quasi-randomised controlled trials evaluating vitamin C supplementation in pregnant women. Interventions using a multivitamin supplement containing vitamin C or where the primary supplement was iron were excluded.

DATA COLLECTION AND ANALYSIS

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

MAIN RESULTS

Five trials, involving 766 women, are included in this review. No difference was seen between women supplemented with vitamin C alone or combined with other supplements compared with placebo for the risk of stillbirth (relative risk (RR) 0.87, 95% confidence intervals (CI) 0.41 to 1.87, three trials, 539 women), perinatal death (RR 1.16, 95% CI 0.61 to 2.18, two trials, 238 women), birthweight (weighted mean difference (WMD) -139.00 g, 95% CI -517.68 to 239.68, one trial, 100 women) or intrauterine growth restriction (RR 0.72, 95% CI 0.49 to 1.04, two trials, 383 women). Women supplemented with vitamin C alone or combined with other supplements were at increased risk of giving birth preterm (RR 1.38, 95% CI 1.04 to 1.82, three trials, 583 women). Significant heterogeneity was found for neonatal death and pre-eclampsia. No difference was seen between women supplemented with vitamin C combined with other supplements for the risk of neonatal death (RR 1.73, 95% CI 0.25 to 12.12, two trials, 221 women), using a random-effects model. For pre-eclampsia, women supplemented with vitamin C combined with other supplements were at decreased risk when using a fixed-effect model (RR 0.47, 95% CI 0.30 to 0.75, four trials, 710 women); however, this difference could not be demonstrated when using a random-effects model (RR 0.52, 95% CI 0.23 to 1.20, four trials, 710 women).

AUTHORS' CONCLUSIONS

The data are too few to say if vitamin C supplementation, alone or combined with other supplements, is beneficial during pregnancy. Preterm birth may have been increased with vitamin C supplementation.