Calcium supplementation in nulliparous women for the prevention of pregnancy-induced hypertension, preeclampsia and preterm birth: an Australian randomized trial. FRACOG and the ACT Study Group

Effectiveness of calcium supplementation in the prevention of gestational hypertension: A systematic review and meta-analysis of randomised controlled trials

BACKGROUND

Gestational hypertension and related disorders, such as preeclampsia, pose significant risks to maternal and foetal health. Calcium supplementation has been proposed as a preventive measure, but its effectiveness remains debated. This review assess the impact of calcium supplementation in prevention of gestational hypertension.

METHODS

A comprehensive literature search was conducted across multiple databases, including Scopus, EMBASE, PubMed, Web of Science, CINAHL, Cochrane CENTRAL, from inception to July 2024. Eligibility criteria included studies involving pregnant women at risk of gestational hypertension, comparing calcium supplementation to control group, and reporting on outcomes such as preeclampsia, pregnancy-induced hypertension, HELLP syndrome, preterm birth, and maternal mortality. Data were analysed using a random-effects inverse-variance model to calculate pooled risk ratios (RRs) and assess heterogeneity using Cochran's Q and I2 statistics. Publication bias was evaluated using funnel plots and Egger's test.

RESULTS

22 studies with 39,270 individuals were included. Most studies had higher risk of bias. Calcium supplementation significantly reduced the risk of preeclampsia (pooled RR = 0.606, 95 %CI: 0.483-0.761, p < 0.001) and pregnancy-induced hypertension (pooled RR = 0.870, 95 %CI: 0.759-0.996, p = 0.044). However, it showed no significant effect on HELLP syndrome, preterm birth, or mortality. Heterogeneity was moderate to substantial across outcomes, and publication bias was detected for preterm birth and pregnancy-induced hypertension.

CONCLUSION

Calcium supplementation during pregnancy significantly reduces the risk of preeclampsia and pregnancy-induced hypertension, highlighting its value as a cost-effective intervention for improving maternal health. These findings support integrating calcium supplementation into prenatal care strategies, particularly for populations with low dietary calcium intake.

Calcium supplementation (other than for preventing or treating hypertension) for improving pregnancy and infant outcomes

BACKGROUND

Maternal nutrition during pregnancy is known to have an effect on fetal growth and development. It is recommended that women increase their calcium intake during pregnancy and lactation, although the recommended dosage varies among professionals. Currently, there is no consensus on the role of routine calcium supplementation for pregnant women other than for preventing or treating hypertension.

OBJECTIVES

To determine the effect of calcium supplementation on maternal, fetal and neonatal outcomes, excluding women with multiple gestation (other than for preventing or treating hypertension), including the occurrence of adverse effects.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (which includes results of comprehensive searches of CENTRAL, MEDLINE, Embase, CINAHL, two trials registers and relevant conference proceedings) on 3 December 2022. We also searched the reference lists of retrieved studies.

SELECTION CRITERIA

We considered all published, unpublished and ongoing randomised controlled trials (RCTs) comparing maternal, fetal and neonatal outcomes in pregnant women who received calcium supplementation versus placebo or no treatment. Cluster-RCTs were eligible for inclusion but none were identified. Quasi-RCTs and cross-over studies were not eligible for inclusion.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion. At least one review author assessed trials meeting the inclusion criteria for trustworthiness, consulting another review author in cases that were not immediately clear. Two review authors independently assessed the studies for risk of bias, extracted data, and checked trials for accuracy. We assessed the certainty of the evidence using GRADE.

MAIN RESULTS

Twenty-one studies met the inclusion criteria, but only 19 studies contributed data to the review. These 19 trials recruited 17,370 women, with 16,625 women included in the final analyses. The trials were generally at low risk of bias for randomisation and allocation concealment. We chose three outcomes for GRADE assessment: preterm birth less than 37 weeks, preterm birth less than 34 weeks and low birthweight (less than 2500 g). All trials compared calcium supplementation with placebo or no treatment with 17 trials comparing high-dose calcium (greater than 1000 mg/day). Calcium supplementation probably slightly reduces the risk of preterm birth less than 37 weeks (average risk ratio (RR) 0.80, 95% confidence interval (CI) 0.65 to 0.99; 11 trials, 15,379 women; moderate-certainty evidence), but probably has little effect on the risk of preterm birth less than 34 weeks (average RR 1.03, 95% CI 0.79 to 1.35; 3 trials, 5569 women; moderate-certainty evidence), and may have little or no effect on low birthweight (less than 2500 g) (average RR 0.93, 95% CI 0.81 to 1.07; 6 trials, 14,162 women; low-certainty evidence; 1 study reported low birthweight (less than 2500 g) but recorded 0 events in both groups. Thus, the RR and CIs were calculated from 5 studies rather than 6). We downgraded the evidence for imprecision (wide CIs crossing the line of no effect) and inconsistency (high levels of heterogeneity between the studies). There was no evidence that calcium supplementation had any effect on maternal weight gain during pregnancy; increasing bone mineral density in pregnant women; rate of intrauterine growth restriction; perinatal mortality; stillbirth or fetal death rate; increase birth length or fetal head circumference; and adverse effects such as postpartum haemorrhage, gall stones, gastrointestinal symptoms, headache, urinary stones, urinary tract infection or impaired renal function.

AUTHORS' CONCLUSIONS

This review indicates that calcium supplementation probably reduces preterm birth before 37 weeks. There are no clear additional benefits to calcium supplementation in preterm birth before 34 weeks or prevention of low birthweight. Large multicentre trials to detect the effect of calcium supplementation on fetal birthweight and preterm birth before 34 weeks as the primary outcomes are needed. Further research into the short- and long-term effects of calcium supplementation would also be beneficial.

Calcium supplementation for the prevention of pre-eclampsia: Challenging the evidence from meta-analyses

OBJECTIVE

To investigate the validity of the conclusion from Cochrane reviews and meta-analyses that treatment with calcium supplementation during pregnancy reduces the risk for pre-eclampsia by 55%, which has been influential in international guidelines and future research.

DESIGN

Sensitivity analysis of data from Cochrane reviews of trials evaluating high-dose calcium supplementation (of at least 1 g/day) for reduction of pre-eclampsia risk.

SETTING

Systematic review and meta-analysis.

POPULATION

The Cochrane reviews and meta-analyses included 13 trials enrolling a total of 15 730 women. Random-effects meta-analysis of these studies resulted in a mean risk ratio (RR, calcium/placebo) of 0.45 (95% confidence interval [CI] 0.31-0.65; p < 0.0001).

METHODS

We carried out a sensitivity analysis of evidence from the relevant Cochrane review, to examine the impact of study size.

MAIN OUTCOME MEASURES

pre-eclampsia.

RESULTS

In the three largest studies, accounting for 13 815 (88%) of total recruitment, mean RR was 0.92 (95% CI 0.80-1.06) and there was no evidence of heterogeneity between studies (I2 = 0). With inclusion of the smaller studies, mean RR decreased to 0.45 and I2 increased to 70%.

CONCLUSIONS

In assessment of the effect of calcium supplementation on pre-eclampsia risk, the naive focus on the mean of the random-effects meta-analysis in the presence of substantial heterogeneity is highly misleading.

Association between calcium supplementation and gestational hypertension, and preeclampsia: A Meta-analysis of 26 randomized controlled trials

BACKGROUND

Pre-eclampsia and eclampsia are common causes of morbidity and mortality, especially in low-income countries. Reducing adverse outcomes associated with hypertensive disorders of pregnancy has been the ultimate priority in recent years. We aim to evaluate the association between calcium supplementation and preeclampsia and gestational hypertension risk among pregnant women.

METHODS

A systematic literature search was performed in electronic databases from inception to 15th July 2023, including only randomized controlled trials. Odds ratio (OR) were, and their corresponding 95% confidence interval (95% CI).

RESULTS

A total of 26 studies with 20,038 patients (10,003 patients with calcium supplements and 10,035 patients with placebo group) were included in the analysis. The Pooled analysis of primary outcome shows that calcium supplements reduce the risk of preeclampsia by 49% (OR, 0.51(95%CI: 0.40-0.66), P<0.001), and reduce the risk of gestational hypertension by 30% (OR, 0.70 (95%CI: 0.58-0.85)), P<0.001) compared to placebo. There was a trend of lower incidence of preterm delivery (OR, 0.88 (95%CI: 0.71-1.09), P=0.23), labor induction (OR, 0.90 (95%CI: 0.78-1.03), P=0.13), small for gestational age (OR, 0.70 (95% CI:0.37-1.32), P = 0.27), low birth weight (OR, 0.96 (95%CI: 0.86-1.08), P=0.53), perinatal mortality (OR, 0.88 (95%CI: 0.72-1.09), P=0.24), and maternal mortality (OR, 0.48 (95%CI: 0.12-1.84), P=0.28) among calcium supplementation group compared with the placebo group, however, statistical signifance was not achieved.

CONCLUSION

This study shows that calcium supplements are associated with a significant reduction in the risk of preeclampsia and gestational hypertension and a trend toward better maternal and fetal-related outcomes.

Maternal-neonatal events resulting from medications for preventing hypertensive disorders in high-risk pregnant women: A systematic review and network meta-analysis

BACKGROUND

There have been few studies reporting on maternal and neonatal events in high-risk pregnant women receiving medications for preventing hypertensive disorders of pregnancy (HDP).

OBJECTIVE

To identify placental abruption, postpartum hemorrhage, neonatal intraventricular hemorrhage, and neonates with small for gestational age (SGA) or growth restriction resulting from medications for preventing HDP in high-risk pregnant women using a network meta-analysis.

SEARCH STRATEGY

All randomized controlled trials comparing the most commonly used medications (antiplatelet agents, anticoagulants, antioxidants, nitric oxide, and calcium) for preventing HDP in high-risk pregnant women were searched from the Cochrane Pregnancy and Childbirth's Specialized Register of Controlled Trials until July 31, 2020, without language restriction.

SELECTION CRITERIA

Two of the authors independently selected the eligible trials.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted the data and assessed the methodological quality of the included trials. Pairwise and network meta-analyses were used to determine comparative risk ratios and 95% confidence intervals.

MAIN RESULTS

The 51 included trials involved 69 669 pregnant women. Compared with placebo/no treatment, antioxidants slightly reduced placental abruption with high-certainty evidence. Antiplatelet agents probably reduced SGA with low-certainty evidence and slightly increased neonatal intraventricular hemorrhage with moderate-certainty evidence.

CONCLUSION

Antiplatelet agents probably reduce SGA, but neonatal intraventricular hemorrhage should be monitored.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO, CRD42018096276.

Counseling pregnant women on calcium: effects on calcium intake

OBJECTIVES

To evaluate the effect of incorporating calcium advice into early pregnancy counseling on calcium intake during pregnancy in the Netherlands.

METHODS

A multicenter prospective before-after cohort study was conducted introducing risk-based care including calculating individual pre-eclampsia risk. Part of the intervention was to incorporate calcium advice into routine counseling. We calculated individual daily calcium intake and adequacy of calcium intake (≥1,000 mg/day) at 16, 24 and 34 weeks of pregnancy. We performed a multiple logistic regression adjusting for covariates to identify any differences in the risk of inadequate calcium intake between RC and CAC.

RESULTS

In regular care (RC, 2013-2015, n=2,477) 60% had inadequate calcium intake, compared to 49% during calcium advice care (CAC, 2017-2018, n=774) (aOR 0.75, 95% CI 0.64-0.88). Specific calcium supplements were used by 2% and 29% in RC and CAC, respectively (OR 25.1, 95% CI 17.8-36.0). Determinants of an inadequate calcium intake were lower age (aOR per additional year 0.96, 95% CI: 0.94-0.98), nulliparity (aOR 1.22, 95% CI: 1.03-1.45) and non-Caucasian origin (aOR 1.83, 95% CI 1.09-3.09). In CAC, risk of inadequate intake decreased with increasing predicted pre-eclampsia risk, which was a trend reversal compared to RC.

CONCLUSIONS

Incorporating calcium advice into early pregnancy counseling was shown to lead to a decrease in the risk of inadequate calcium intake during pregnancy, but still inadequate intake in half of the women suggesting the need for further study on improving implementation. Awareness of individual increased PE risk had positive effect on calcium intake.

Calcium for pre-eclampsia prevention: A systematic review and network meta-analysis to guide personalised antenatal care

BACKGROUND

Calcium supplementation reduces the risk of pre-eclampsia, but questions remain about the dosage to prescribe and who would benefit most.

OBJECTIVES

To evaluate the effectiveness of high (≥1 g/day) and low (<1 g/day) calcium dosing for pre-eclampsia prevention, according to baseline dietary calcium, pre-eclampsia risk and co-interventions, and intervention timing.

SEARCH STRATEGY

CENTRAL, PubMed, Global Index Medicus and CINAHL, from inception to 2 February 2021, clinical trial registries, reference lists and expert input (CRD42018111239).

SELECTION CRITERIA

Randomised controlled trials of calcium supplementation for pre-eclampsia prevention, for women before or during pregnancy. Network meta-analysis (NMA) also included trials of different calcium doses.

DATA COLLECTION AND ANALYSIS

Two independent reviewers extracted published data. The meta-analysis employed random-effects models and the NMA, a Bayesian random-effects model, to obtain direct and indirect effect estimates.

MAIN RESULTS

The meta-analysis included 30 trials (N = 20 445 women), and the NMA to evaluate calcium dosage included 25 trials (N = 15 038). Calcium supplementation prevented pre-eclampsia similarly with a high dose (RR 0.49, 95% CI 0.36-0.66) or a low dose (RR 0.49, 95% CI 0.36-0.65). By NMA, high-dose (vs low-dose) calcium did not differ in effect (RR 0.79, 95% CI 0.43-1.40). Calcium was similarly effective regardless of baseline pre-eclampsia risk, vitamin D co-administration or timing of calcium initiation, but calcium was ineffective among women with adequate average baseline calcium intake.

CONCLUSIONS

Low- and high-dose calcium supplementation are effective for pre-eclampsia prevention in women with low calcium intake. This has implications for population-level implementation where dietary calcium is low, and targeted implementation where average intake is adequate.

TWEETABLE ABSTRACT

A network meta-analysis of 25 trials found that low-dose calcium supplementation (<1 g/day) is as effective as high-dose calcium supplementation (≥1 g/day) in halving the risk of pre-eclampsia when baseline calcium intake is low.

Medications for preventing hypertensive disorders in high-risk pregnant women: a systematic review and network meta-analysis

OBJECTIVES

To determine the relative effectiveness of medications for preventing hypertensive disorders in high-risk pregnant women and to provide a ranking of medications using network meta-analysis.

METHODS

All randomized controlled trials comparing the most commonly used medications to prevent hypertensive disorders in high-risk pregnant women that are nulliparity and pregnant women having family history of preeclampsia, history of pregnancy-induced hypertension in previous pregnancy, obstetric risks, or underlying medical diseases. We received the search results from the Cochrane Pregnancy and Childbirth's Specialised Register of Controlled Trials, searched on 31st July 2020. At least two review authors independently selected the included studies and extracted the data and the methodological quality. The comparative risk ratios (RR) and 95% confidence intervals (CI) were analyzed using pairwise and network meta-analyses, and treatment rankings were estimated by the surface under the cumulative ranking curve for preventing preeclampsia (PE), gestational hypertension (GHT), and superimposed preeclampsia (SPE). Safety of the medications is also important for decision-making along with effectiveness which will be reported in a separate review.

RESULTS

This network meta-analysis included 83 randomized studies, involving 93,864 women across global regions. Three medications, either alone or in combination, probably prevented PE in high-risk pregnant women when compared with a placebo or no treatment from network analysis: antiplatelet agents with calcium (RR 0.19, 95% CI 0.04 to 0.86; 1 study; low-quality evidence), calcium (RR 0.61, 95% CI 0.47 to 0.80; 13 studies; moderate-quality evidence), antiplatelet agents (RR 0.69, 95% CI 0.57 to 0.82; 31 studies; moderate-quality evidence), and antioxidants (RR 0.77, 95% CI 0.63 to 0.93; 25 studies; moderate-quality evidence). Calcium probably prevented PE (RR 0.63, 95% CI 0.46 to 0.86; 11 studies; moderate-quality evidence) and GHT (RR 0.89, 95% CI 0.84 to 0.95; 8 studies; high-quality evidence) in nulliparous/primigravida women. Few included studies for the outcome of superimposed preeclampsia were found.

CONCLUSION

Antiplatelet agents, calcium, and their combinations were most effective medications for preventing hypertensive disorders in high-risk pregnant women when compared with a placebo or no treatment. Any high-risk characteristics for women are important in deciding the best medications. The qualities of evidence were mostly rated to be moderate.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42018096276.

Different Doses of Calcium Supplementation to Prevent Gestational Hypertension and Pre-Eclampsia: A Systematic Review and Network Meta-Analysis

Objective

Calcium supplementation can prevent gestational hypertension and pre-eclampsia. However, besides the non-consensus of existing studies, there is a lack of evidence regarding the optimal dosing of calcium.

Method

Eight electronic databases, namely, the Cochrane Library, PUBMED, Web of Science, EMBASE, WANGFANG, VIP, CBM, and CNKI, were searched. The studies were retrieved from inception to July 13, 2021. Two researchers independently screened the literature, extracted data, and evaluated the methodological quality based on the inclusion criteria. In particular, the calcium supplementation doses were divided into three groups, namely, the high-dose (≥1.5 g), medium-dose (1.0–1.49 g), and the low-dose group (<1.0 g). The participants were also divided into high-risk and low-risk groups, according to the risk of developing gestational hypertension and pre-eclampsia.

Results and Discussion

A total of 48 studies were incorporated into the final analyses. All doses of calcium supplementation reduced the incidence of gestational hypertension in the low-risk population (low dose - three studies; medium dose- 11 studies; high dose- 28 studies), whereas the medium-dose (three studies) reduced the incidence of gestational hypertension in high-risk groups. Moreover, a medium dose of calcium supplementation had the maximum effect in reducing gestational hypertension in low-risk and high-risk populations. The medium (three studies) and high doses (13 studies) of calcium supplementation reduced the incidence of pre-eclampsia in the low-risk groups. However, a medium-dose calcium supplementation maximally prevented pre-eclampsia in the low-risk population. The authenticity and reliability of the results were reduced due to the limitations of contemporary studies in terms of experimental design, result measurement, statistics, and evidence quality. Therefore, high-quality studies with larger sample size are required to evaluate further the effect of calcium supplementation in preventing gestational hypertension and pre-eclampsia.

Calcium supplementation during pregnancy and long‐term offspring outcome: a systematic literature review and meta‐analysis

The World Health Organization currently recommends calcium supplementation for pregnant women, especially those with low calcium intakes, to reduce the risk of hypertension and preeclampsia. We aimed to evaluate the effect of this intervention on selected offspring outcomes. A systematic search was conducted in 11 databases for published randomized controlled trials (RCTs) on the effect of maternal calcium supplementation with or without vitamin D during pregnancy on selected offspring cardiovascular, growth, and metabolic and neurodevelopmental outcomes. Screening of titles and abstracts of 3555 records and full texts of 31 records yielded six RCTs (nine reports, n = 1616). Forest plot analyses were performed if at least two studies presented comparable data on the same outcome. In one study (n = 591), high‐dose calcium supplementation during pregnancy was associated with a decreased risk of offspring high systolic blood pressure at 5–7 years of age (risk ratio = 0.59; 95% confidence interval: 0.39–0.90). The effects of the intervention on offspring growth, metabolic, and neurodevelopmental outcomes remain unknown because of conflicting or insufficient data. High risk of attrition bias decreased the quality of the evidence. Limited available data from RCTs do not provide sufficient evidence to conclude that prenatal calcium supplementation influences offspring health outcomes beyond the newborn period.

Effects of vitamin and mineral supplementation during pregnancy on maternal, birth, child health and development outcomes in low- and middle-income countries: A systematic review

Background

Almost two billion people who are deficient in vitamins and minerals are women and children in low- and middle-income countries (LMIC). These deficiencies are worsened during pregnancy due to increased energy and nutritional demands, causing adverse outcomes in mother and child. To reduce micronutrient deficiencies, several strategies have been implemented, including diet diversification, large-scale and targeted fortification, staple crop bio-fortification and micronutrient supplementation.

Objectives

To evaluate and summarize the available evidence on the effects of micronutrient supplementation during pregnancy in LMIC on maternal, fetal, child health and child development outcomes. This review will assess the impact of single micronutrient supplementation (calcium, vitamin A, iron, vitamin D, iodine, zinc, vitamin B12), iron-folic acid (IFA) supplementation, multiple micronutrient (MMN) supplementation, and lipid-based nutrient supplementation (LNS) during pregnancy.

Search Methods

We searched papers published from 1995 to 31 October 2019 (related programmes and good quality studies pre-1995 were limited) in CAB Abstracts, CINAHL, Cochrane Central Register of Controlled Trials, Embase, International Initiative for Impact Evaluations, LILACS, Medline, POPLINE, Web of Science, WHOLIS, ProQuest Dissertations & Theses Global, R4D, WHO International Clinical Trials Registry Platform. Non-indexed grey literature searches were conducted using Google, Google Scholar, and web pages of key international nutrition agencies.

Selection Criteria

We included randomized controlled trials (individual and cluster-randomized) and quasi-experimental studies that evaluated micronutrient supplementation in healthy, pregnant women of any age and parity living in a LMIC. LMIC were defined by the World Bank Group at the time of the search for this review. While the aim was to include healthy pregnant women, it is likely that these populations had one or more micronutrient deficiencies at baseline; women were not excluded on this basis.

Data Collection and Analysis

Two authors independently assessed studies for inclusion and risk of bias, and conducted data extraction. Data were matched to check for accuracy. Quality of evidence was assessed using the GRADE approach.

Main Results

A total of 314 papers across 72 studies (451,723 women) were eligible for inclusion, of which 64 studies (439,649 women) contributed to meta-analyses. Seven studies assessed iron-folic acid (IFA) supplementation versus folic acid; 34 studies assessed MMN vs. IFA; 4 studies assessed LNS vs. MMN; 13 evaluated iron; 13 assessed zinc; 9 evaluated vitamin A; 11 assessed vitamin D; and 6 assessed calcium. Several studies were eligible for inclusion in multiple types of supplementation. IFA compared to folic acid showed a large and significant (48%) reduction in the risk of maternal anaemia (average risk ratio (RR) 0.52, 95% CI 0.41 to 0.66; studies = 5; participants = 15,540; moderate-quality evidence). As well, IFA supplementation demonstrated a smaller but significant, 12% reduction in risk of low birthweight (LBW) babies (average RR 0.88, 95% CI 0.78 to 0.99; studies = 4; participants = 17,257; high-quality evidence). MMN supplementation was defined as any supplement that contained at least 3 micronutrients. Post-hoc analyses were conducted, where possible, comparing the differences in effect of MMN with 4+ components and MMN with 3 or 4 components. When compared to iron with or without FA, MMN supplementation reduced the risk of LBW by 15% (average RR 0.85, 95% CI 0.77 to 0.93; studies = 28; participants = 79,972); this effect was greater in MMN with >4 micronutrients (average RR 0.79, 95% CI 0.71 to 0.88; studies = 19; participants = 68,138 versus average RR 1.01, 95% CI 0.92 to 1.11; studies = 9; participants = 11,834). There was a small and significant reduction in the risk of stillbirths (average RR 0.91; 95% CI 0.86 to 0.98; studies = 22; participants = 96,772) and a small and significant effect on the risk of small-for-gestational age (SGA) (average RR 0.93; 95% CI 0.88 to 0.98; studies = 19; participants = 52,965). For stillbirths and SGA, the effects were greater among those provided MMN with 4+ micronutrients. Children whose mothers had been supplemented with MMN, compared to IFA, demonstrated a 16% reduced risk of diarrhea (average RR 0.84; 95% CI 0.76 to 0.92; studies = 4; participants = 3,142). LNS supplementation, compared to MMN, made no difference to any outcome; however, the evidence is limited. Iron supplementation, when compared to no iron or placebo, showed a large and significant effect on maternal anaemia, a reduction of 47% (average RR 0.53, 95% CI 0.43 to 0.65; studies = 6; participants = 15,737; moderate-quality evidence) and a small and significant effect on LBW (average RR 0.88, 95% CI 0.78 to 0.99; studies = 4; participants = 17,257; high-quality evidence). Zinc and vitamin A supplementation, each both compared to placebo, had no impact on any outcome examined with the exception of potentially improving serum/plasma zinc (mean difference (MD) 0.43 umol/L; 95% CI -0.04 to 0.89; studies = 5; participants = 1,202) and serum/plasma retinol (MD 0.13 umol/L; 95% CI -0.03 to 0.30; studies = 6; participants = 1,654), respectively. When compared to placebo, vitamin D supplementation may have reduced the risk of preterm births (average RR 0.64; 95% CI 0.40 to 1.04; studies = 7; participants = 1,262), though the upper CI just crosses the line of no effect. Similarly, calcium supplementation versus placebo may have improved rates of pre-eclampsia/eclampsia (average RR 0.45; 95% CI 0.19 to 1.06; studies = 4; participants = 9,616), though the upper CI just crosses 1.

Authors' Conclusions

The findings suggest that MMN and vitamin supplementation improve maternal and child health outcomes, including maternal anaemia, LBW, preterm birth, SGA, stillbirths, micronutrient deficiencies, and morbidities, including pre-eclampsia/eclampsia and diarrhea among children. MMN supplementation demonstrated a beneficial impact on the most number of outcomes. In addition, MMN with >4 micronutrients appeared to be more impactful than MMN with only 3 or 4 micronutrients included in the tablet. Very few studies conducted longitudinal analysis on longer-term health outcomes for the child, such as anthropometric measures and developmental outcomes; this may be an important area for future research. This review may provide some basis to guide continual discourse around replacing IFA supplementation with MMN along with the use of single micronutrient supplementation programs for specific outcomes.

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).

An observational study on Ca supplementation and dietary intake during pregnancy on low birth weight and small for gestational age

OBJECTIVE

To evaluate the effects of dietary Ca intake and Ca supplementation during pregnancy on low birth weight (LBW) and small for gestational age (SGA) infants.

DESIGN

A birth cohort study was conducted in 2010-2012 at the Gansu Provincial Maternity and Child Care Hospital in Lanzhou, China.

SETTING

A birth cohort study.

PARTICIPANTS

Totally, 9595 pregnant women who came to the hospital for delivery at 20 weeks of gestation or more, and who were 18 years of age or older.

RESULTS

Compared with non-users, Ca supplement users had a reduced risk of LBW infants (OR = 0·77, 95 % CI: 0·63, 0·95) and a reduced risk of nulliparous women giving birth to LBW infants (OR = 0·75, 95 % CI: 0·58, 0·98) (P < 0·05). More specifically, both the use of Ca supplement before conception and during pregnancy (OR = 0·44, 95 % CI: 0·19, 0·99) and during pregnancy only (OR = 0·80, 95 % CI: 0·65, 0·99) had the main effect of reducing risk of nulliparous women giving birth to LBW infants (P < 0·05). There was no association between Ca supplementation and SGA (OR = 0·87, 95 % CI: 0·75, 1·01) (P > 0·05). However, higher dietary Ca intake during pregnancy decreases the risk of both LBW (quartile 2: OR = 0·72, 95 % CI: 0·55, 0·94; quartile 3: OR = 0·68, 95 % CI: 0·50, 0·62) and SGA infants (quartile 2: OR = 0·77, 95 % CI: 0·63, 0·95; quartile 3: OR = 0·71, 95 % CI: 0·57, 0·88, quartile 4: OR = 0·71, 95 % CI: 0·57, 0·88) (P < 0·05).

CONCLUSIONS

Ca supplementation and adequate dietary intake of Ca during pregnancy are associated with a decreased risk of LBW infants born to nulliparous women.

Associations between maternal calcium intake from diet and supplements during pregnancy and the risk of preterm birth in a Chinese population

BACKGROUND/OBJECTIVES

Preterm birth is a global public health priority related to maternal nutrition. The effect of maternal calcium intake during pregnancy on preterm birth is inconclusive and data is lacking in China. We aimed to estimate the role of calcium intake from diet and supplements on preterm birth in the Chinese population.

METHODS

We used data of 7195 women from a large-scale cross-sectional study in Northwest China. Dietary intake was evaluated via a validated food frequency questionnaire, and other information was collected by a structured questionnaire. Generalized estimating equation models were used to estimate the relationship between calcium intake and preterm birth.

RESULTS

Inadequate dietary calcium intake was universal in our population (85.9%), and no association was found between daily dietary calcium intake and preterm birth. Maternal calcium supplementation was significantly associated with reduced risk of preterm birth (OR 0.72, 95% CI 0.60, 0.87, P = 0.001), particularly among women who commenced calcium supplementation in the second and third trimester of pregnancy with longer duration (OR 0.62, 95% CI 0.42, 0.91, P = 0.015). Higher daily calcium intake from supplements was linked with lower preterm birth risk (every 100 mg increase: OR 0.87, 95% CI 0.79, 0.96, P = 0.004). There is a negative association between daily total calcium intake and preterm birth among calcium supplement users (every 100 mg increase: OR 0.91, 95% CI 0.84, 0.97, P = 0.007).

CONCLUSIONS

In conclusion, appropriate calcium supplementation during pregnancy could be beneficial in the prevention of preterm birth, and it might be suitable for implementing in low calcium intake areas of China.

Calcium intake from diet and supplement use during early pregnancy: the Expect study I

PURPOSE

Adequate calcium intake during pregnancy is of major importance for the health of both mother and fetus. Up to date, evidence on the prevalence of inadequate calcium intake among pregnant women is sparse for Western countries, and it is unknown to what extent inadequate dietary calcium intake is adequately balanced by supplement use. The objective of this study was to estimate calcium intake from diet and supplement use during the early pregnancy in The Netherlands.

METHODS

As part of the Expect cohort study, 2477 pregnant women (8-16 weeks of gestation) completed an online questionnaire including questions on baseline characteristics, the use of calcium containing supplements, and a short food-frequency questionnaire (FFQ). Intake data were used to calculate median calcium intakes from diet, from supplements, and combined, and to compare these values with currently accepted requirement levels.

RESULTS

Forty-two percent of the pregnant women had a total calcium intake below the estimated average requirement of 800 mg/day. Median (interquartile range) calcium intake was 886 (611-1213) mg/day. Calcium or multivitamin supplements were used by 64.8% of the women at 8 weeks of gestation, with a median calcium content of 120.0 (60.0-200.0) mg/day. Prenatal vitamins were the most often used supplements (60.6%).

CONCLUSIONS

Forty-two percent of Dutch pregnant women have an inadequate calcium intake. Supplements are frequently used, but most do not contain sufficient amounts to correct this inadequate intake.

Prepregnancy and early pregnancy calcium supplementation among women at high risk of pre-eclampsia: a multicentre, double-blind, randomised, placebo-controlled trial

BACKGROUND

Reducing deaths from hypertensive disorders of pregnancy is a global priority. Low dietary calcium might account for the high prevalence of pre-eclampsia and eclampsia in low-income countries. Calcium supplementation in the second half of pregnancy is known to reduce the serious consequences of pre-eclampsia; however, the effect of calcium supplementation during placentation is not known. We aimed to test the hypothesis that calcium supplementation before and in early pregnancy (up to 20 weeks' gestation) prevents the development of pre-eclampsia METHODS: We did a multicountry, parallel arm, double-blind, randomised, placebo-controlled trial in South Africa, Zimbabwe, and Argentina. Participants with previous pre-eclampsia and eclampsia received 500 mg calcium or placebo daily from enrolment prepregnancy until 20 weeks' gestation. Participants were parous women whose most recent pregnancy had been complicated by pre-eclampsia or eclampsia and who were intending to become pregnant. All participants received unblinded calcium 1·5 g daily after 20 weeks' gestation. The allocation sequence (1:1 ratio) used computer-generated random numbers in balanced blocks of variable size. The primary outcome was pre-eclampsia, defined as gestational hypertension and proteinuria. The trial is registered with the Pan-African Clinical Trials Registry, number PACTR201105000267371. The trial closed on Oct 31, 2017.

FINDINGS

Between July 12, 2011, and Sept 8, 2016, we randomly allocated 1355 women to receive calcium or placebo; 331 of 678 participants in the calcium group versus 320 of 677 in the placebo group became pregnant, and 298 of 678 versus 283 of 677 had pregnancies beyond 20 weeks' gestation. Pre-eclampsia occurred in 69 (23%) of 296 participants in the calcium group versus 82 (29%) of 283 participants in the placebo group with pregnancies beyond 20 weeks' gestation (risk ratio [RR] 0·80, 95% CI 0·61-1·06; p=0·121). For participants with compliance of more than 80% from the last visit before pregnancy to 20 weeks' gestation, the pre-eclampsia risk was 30 (21%) of 144 versus 47 (32%) of 149 (RR 0·66, CI 0·44-0·98; p=0·037). There were no serious adverse effects of calcium reported.

INTERPRETATION

Calcium supplementation that commenced before pregnancy until 20 weeks' gestation, compared with placebo, did not show a significant reduction in recurrent pre-eclampsia. As the trial was powered to detect a large effect size, we cannot rule out a small to moderate effect of this intervention.

FUNDING

The University of British Columbia, a grantee of the Bill & Melinda Gates Foundation; UNDP-UNFPA-UNICEF-WHO-World Bank Special Programme of Research, Development and Research Training in Human Reproduction, WHO; the Argentina Fund for Horizontal Cooperation of the Argentinean Ministry of Foreign Affairs; and the Centre for Intervention Science in Maternal and Child Health.

Calcium supplementation during pregnancy for preventing hypertensive disorders and related problems

BACKGROUND

Pre-eclampsia and eclampsia are common causes of serious morbidity and death. Calcium supplementation may reduce the risk of pre-eclampsia, and may help to prevent preterm birth. This is an update of a review last published in 2014.

OBJECTIVES

To assess the effects of calcium supplementation during pregnancy on hypertensive disorders of pregnancy and related maternal and child outcomes.

SEARCH METHODS

We searched Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform (ICTRP) (18 September 2017), and reference lists of retrieved studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs), including cluster-randomised trials, comparing high-dose calcium supplementation (at least 1 g daily of calcium) during pregnancy with placebo. For low-dose calcium we included quasi-randomised trials, trials without placebo, trials with cointerventions and dose comparison trials.

DATA COLLECTION AND ANALYSIS

Two researchers independently assessed trials for inclusion and risk of bias, extracted data and checked them for accuracy. Two researchers assessed the evidence using the GRADE approach.

MAIN RESULTS

We included 27 studies (18,064 women). We assessed the included studies as being at low risk of bias, although bias was frequently difficult to assess due to poor reporting and inadequate information on methods.High-dose calcium supplementation (≥ 1 g/day) versus placeboFourteen studies examined this comparison, however one study contributed no data. The 13 studies contributed data from 15,730 women to our meta-analyses. The average risk of high blood pressure (BP) was reduced with calcium supplementation compared with placebo (12 trials, 15,470 women: risk ratio (RR) 0.65, 95% confidence interval (CI) 0.53 to 0.81; I² = 74%). There was also a reduction in the risk of pre-eclampsia associated with calcium supplementation (13 trials, 15,730 women: average RR 0.45, 95% CI 0.31 to 0.65; I² = 70%; low-quality evidence). This effect was clear for women with low calcium diets (eight trials, 10,678 women: average RR 0.36, 95% CI 0.20 to 0.65; I² = 76%) but not those with adequate calcium diets. The effect appeared to be greater for women at higher risk of pre-eclampsia, though this may be due to small-study effects (five trials, 587 women: average RR 0.22, 95% CI 0.12 to 0.42). These data should be interpreted with caution because of the possibility of small-study effects or publication bias. In the largest trial, the reduction in pre-eclampsia was modest (8%) and the CI included the possibility of no effect.The composite outcome maternal death or serious morbidity was reduced with calcium supplementation (four trials, 9732 women; RR 0.80, 95% CI 0.66 to 0.98). Maternal deaths were no different (one trial of 8312 women: one death in the calcium group versus six in the placebo group). There was an anomalous increase in the risk of HELLP syndrome in the calcium group (two trials, 12,901 women: RR 2.67, 95% CI 1.05 to 6.82, high-quality evidence), however, the absolute number of events was low (16 versus six).The average risk of preterm birth was reduced in the calcium supplementation group (11 trials, 15,275 women: RR 0.76, 95% CI 0.60 to 0.97; I² = 60%; low-quality evidence); this reduction was greatest amongst women at higher risk of developing pre-eclampsia (four trials, 568 women: average RR 0.45, 95% CI 0.24 to 0.83; I² = 60%). Again, these data should be interpreted with caution because of the possibility of small-study effects or publication bias. There was no clear effect on admission to neonatal intensive care. There was also no clear effect on the risk of stillbirth or infant death before discharge from hospital (11 trials, 15,665 babies: RR 0.90, 95% CI 0.74 to 1.09).One study showed a reduction in childhood systolic BP greater than 95th percentile among children exposed to calcium supplementation in utero (514 children: RR 0.59, 95% CI 0.39 to 0.91). In a subset of these children, dental caries at 12 years old was also reduced (195 children, RR 0.73, 95% CI 0.62 to 0.87).Low-dose calcium supplementation (< 1 g/day) versus placebo or no treatmentTwelve trials (2334 women) evaluated low-dose (usually 500 mg daily) supplementation with calcium alone (four trials) or in association with vitamin D (five trials), linoleic acid (two trials), or antioxidants (one trial). Most studies recruited women at high risk for pre-eclampsia, and were at high risk of bias, thus the results should be interpreted with caution. Supplementation with low doses of calcium reduced the risk of pre-eclampsia (nine trials, 2234 women: RR 0.38, 95% CI 0.28 to 0.52). There was also a reduction in high BP (five trials, 665 women: RR 0.53, 95% CI 0.38 to 0.74), admission to neonatal intensive care unit (one trial, 422 women, RR 0.44, 95% CI 0.20 to 0.99), but not preterm birth (six trials, 1290 women, average RR 0.83, 95% CI 0.34 to 2.03), or stillbirth or death before discharge (five trials, 1025 babies, RR 0.48, 95% CI 0.14 to 1.67).High-dose (=/> 1 g) versus low-dose (< 1 g) calcium supplementationWe included one trial with 262 women, the results of which should be interpreted with caution due to unclear risk of bias. Risk of pre-eclampsia appeared to be reduced in the high-dose group (RR 0.42, 95% CI 0.18 to 0.96). No other differences were found (preterm birth: RR 0.31, 95% CI 0.09 to 1.08; eclampsia: RR 0.32, 95% CI 0.07 to 1.53; stillbirth: RR 0.48, 95% CI 0.13 to 1.83).

AUTHORS' CONCLUSIONS

High-dose calcium supplementation (≥ 1 g/day) may reduce the risk of pre-eclampsia and preterm birth, particularly for women with low calcium diets (low-quality evidence). The treatment effect may be overestimated due to small-study effects or publication bias. It reduces the occurrence of the composite outcome 'maternal death or serious morbidity', but not stillbirth or neonatal high care admission. There was an increased risk of HELLP syndrome with calcium supplementation, which was small in absolute numbers.The limited evidence on low-dose calcium supplementation suggests a reduction in pre-eclampsia, hypertension and admission to neonatal high care, but needs to be confirmed by larger, high-quality trials.

Calcium and Vitamin D Supplementation for Prevention of Preeclampsia: A Systematic Review and Network Meta-Analysis

Vitamin D supplementation effects with or without calcium in pregnancy for reducing risk of preeclampsia and gestational or pregnancy induced hypertension are controversial. Literature was systematically searched in Medline, Scopus and Cochrane databases from inception to July 2017. Only randomized controlled trials (RCTs) in English were selected if they had any pair of interventions (calcium, vitamin D, both, or placebo). Systematic review with two-step network-meta-analysis was used to indirectly estimate supplementary effects. Twenty-seven RCTs with 28,000 women were eligible. A direct meta-analysis suggested that calcium, vitamin D, and calcium plus vitamin D could lower risk of preeclampsia when compared to placebo with the pooled risk ratios (RRs) of 0.54 (0.41, 0.70), 0.47 (0.24, 0.89) and 0.50 (0.32, 0.78), respectively. Results of network meta-analysis were similar with the corresponding RRs of 0.49 (0.35, 0.69), 0.43 (0.17, 1.11), and 0.57 (0.30, 1.10), respectively. None of the controls were significant. Efficacy of supplementation, which was ranked by surface under cumulative ranking probabilities, were: vitamin D (47.4%), calcium (31.6%) and calcium plus vitamin D (19.6%), respectively. Calcium supplementation may be used for prevention for preeclampsia. Vitamin D might also worked well but further large scale RCTs are warranted to confirm our findings.

Serum magnesium and calcium in preeclampsia: a comparative study at the Korle-Bu Teaching Hospital, Ghana

Background

A large percentage (16% of maternal mortality in developed countries, compared to 9% in developing countries), is due to hypertensive disorders in pregnancy. The etiology of preeclampsia remains unknown, with poorly understood pathophysiology. Magnesium and calcium play an important role in vascular smooth muscle function and therefore a possible role in the development of preeclampsia.

Aim

We aimed to compare serum magnesium and total calcium levels of preeclamptic and normal pregnant women at the Korle-Bu Teaching Hospital in Ghana.

Patients and methods

A comparative cross-sectional study involving 30 normal pregnant and 30 preeclamptic women with >30 weeks gestation and aged 18–35 years, was conducted at the Korle-Bu Teaching Hospital. Magnesium and calcium were determined using a flame atomic absorption spectrometer.

Results

Mean serum magnesium and total calcium levels in preeclamptic women were 0.70±0.15 and 2.13±0.30 mmol/L, respectively. Mean serum magnesium and total calcium levels in normal pregnant women were 0.76±0.14 and 2.13±0.35 mmol/L, respectively. There was a statistically nonsignificant difference in serum magnesium and total calcium in preeclamptic women compared to normal pregnant women, with p-values of 0.092 and 0.972, respectively.

Conclusion

Serum magnesium and total calcium, therefore, seem not to differ in preeclamptic women compared to normal pregnant women in Ghana.

Comparison of Serum Calcium and Magnesium Between Preeclamptic and Normotensive Pregnant Nigerian Women in Abakaliki, Nigeria

Background:

Evidence suggests the involvement of calcium and magnesium metabolism in the pathophysiology of preeclampsia. However, findings from studies are heterogenous and inconsistent.

Aim:

The study aimed to compare the total serum calcium and magnesium levels in preeclamptic women with that of normotensive pregnant women.

Subjects and Methods:

A cross-sectional subjects of eighty pregnant women living in Abakaliki, Ebonyi state, South-East Nigeria, were recruited into the study. The present study compared serum calcium and magnesium in forty preeclamptic (cases) and forty normotensive (control) pregnant women matched for age, parity, and socioeconomic status. Serum calcium and magnesium levels were measured using atomic absorption spectrophotometer. Statistical analysis was done using SPSS Version 20 statistical software. Differences between means were compared using Student's t-test with P < 0.05 considered as statistically significant.

Results:

While the mean serum calcium was comparable between preeclamptic and normotensive pregnant women (13.99 [3.29] vs. 14.02 [5.68] μg/dl), the preeclamptic pregnant women have significantly (P < 0.001) lower serum magnesium in comparison to their normotensive counterparts (3.22 [1.05] vs. 4.15 [0.78]).

Conclusion:

It may be concluded that serum magnesium seems to play a crucial role in the pathophysiology of preeclampsia in this environment.

Increased planned delivery contributes to declining rates of pregnancy hypertension in Australia: a population-based record linkage study

OBJECTIVE

Since the 1990s, pregnancy hypertension rates have declined in some countries, but not all. Increasing rates of early planned delivery (before the due date) have been hypothesised as the reason for the decline. The aim of this study was to explore whether early planned delivery can partly explain the declining pregnancy hypertension rates in Australia.

DESIGN

Population-based record linkage study utilising linked birth and hospital records.

SETTING AND PARTICIPANTS

A cohort of 1,076,122 deliveries in New South Wales, Australia, 2001-2012.

OUTCOME MEASURES

Pregnancy hypertension (including gestational hypertension, pre-eclampsia and eclampsia) was the main outcome; pre-eclampsia was a secondary outcome.

RESULTS

From 2001 to 2012, pregnancy hypertension rates declined by 22%, from 9.9% to 7.7%, and pre-eclampsia by 27%, from 3.3% to 2.4% (trend p<0.0001). At the same time, planned deliveries increased: prelabour caesarean section by 43% (12.9-18.4%) and labour inductions by 10% (24.8-27.2%). Many maternal risk factors for pregnancy hypertension significantly increased (p<0.01) over the study period including nulliparity, age ≥35 years, diabetes, overweight and obesity, and use of assisted reproductive technologies; some risk factors decreased including multifetal pregnancies, age <20 years, autoimmune diseases and previous pregnancy hypertension. Given these changes in risk factors, the pregnancy hypertension rate was predicted to increase to 10.5%. Examination of annual gestational age distributions showed that pregnancy hypertension rates actually declined from 38 weeks gestation and were steepest from 41 weeks; at least 36% of the decrease could be attributed to planned deliveries. The risk factors for pregnancy hypertension were also risk factors for planned delivery.

CONCLUSIONS

It appears that an unanticipated consequence of increasing early planned deliveries is a decline in the incidence of pregnancy hypertension. Women with risk factors for hypertension were relatively more likely to be selected for early delivery.

Potential role of folate in pre-eclampsia

Dietary deficiencies of folate and other B vitamin cofactors involved in one-carbon metabolism, together with genetic polymorphisms in key folate-methionine metabolic pathway enzymes, are associated with increases in circulating plasma homocysteine, reduction in DNA methylation patterns, and genome instability events. All of these biomarkers have also been associated with pre-eclampsia. The aim of this review was to explore the literature and identify potential knowledge gaps in relation to the role of folate at the genomic level in either the etiology or the prevention of pre-eclampsia. A systematic search strategy was designed to identify citations in electronic databases for the following terms: folic acid supplementation AND pre-eclampsia, folic acid supplementation AND genome stability, folate AND genome stability AND pre-eclampsia, folic acid supplementation AND DNA methylation, and folate AND DNA methylation AND pre-eclampsia. Forty-three articles were selected according to predefined selection criteria. The studies included in the present review were not homogeneous, which made pooled analysis of the data very difficult. The present review highlights associations between folate deficiency and certain biomarkers observed in various tissues of women at risk of pre-eclampsia. Further investigation is required to understand the role of folate in either the etiology or the prevention of pre-eclampsia.

Bioactive factors in uteroplacental and systemic circulation link placental ischemia to generalized vascular dysfunction in hypertensive pregnancy and preeclampsia

Preeclampsia is a pregnancy-associated disorder characterized by hypertension, and could lead to maternal and fetal morbidity and mortality; however, the pathophysiological mechanisms involved are unclear. Predisposing demographic, genetic and environmental risk factors could cause localized abnormalities in uteroplacental cytoactive factors such as integrins, matrix metalloproteinases, cytokines and major histocompatibility complex molecules leading to decreased vascular remodeling, uteroplacental vasoconstriction, trophoblast cells apoptosis, and abnormal development of the placenta. Defective placentation and decreased trophoblast invasion of the myometrium cause reduction in uteroplacental perfusion pressure (RUPP) and placental ischemia/hypoxia, an important event in preeclampsia. RUPP could stimulate the release of circulating bioactive factors such as the anti-angiogenic factors soluble fms-like tyrosine kinase-1 and soluble endoglin that cause imbalance with the pro-angiogenic factors vascular endothelial growth factor and placental growth factor, or cause the release of inflammatory cytokines, reactive oxygen species, hypoxia-induced factor-1 and AT1 angiotensin receptor agonistic autoantibodies. The circulating bioactive factors target endothelial cells causing generalized endotheliosis, endothelial dysfunction, decreased vasodilators such as nitric oxide and prostacyclin and increased vasoconstrictors such as endothelin-1 and thromboxane A2, leading to increased vasoconstriction. The bioactive factors also stimulate the mechanisms of VSM contraction including Ca(2+), protein kinase C, and Rho-kinase and induce extracellular matrix remodeling leading to further vasoconstriction and hypertension. While therapeutic options are currently limited, understanding the underlying mechanisms could help design new interventions for management of preeclampsia.

Calcium supplementation (other than for preventing or treating hypertension) for improving pregnancy and infant outcomes

BACKGROUND

Maternal nutrition during pregnancy is known to have an effect on fetal growth and development. It is recommended that women increase their calcium intake during pregnancy and lactation, although the recommended dosage varies among professionals. Currently, there is no consensus on the role of routine calcium supplementation for pregnant women other than for preventing or treating hypertension.

OBJECTIVES

To determine the effect of calcium supplementation on maternal, fetal and neonatal outcomes (other than for preventing or treating hypertension) as well as any possible side effects.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (30th September 2014).

SELECTION CRITERIA

We considered all published, unpublished and ongoing randomised controlled trials (RCTs) comparing maternal, fetal and neonatal outcomes in pregnant women who received calcium supplementation versus placebo or no treatment. Cluster-RCTs were eligible for inclusion but none were identified. Quasi-RCTs and cross-over studies were not eligible for inclusion.

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-five studies met the inclusion criteria, but only 23 studies contributed data to the review. These 23 trials recruited 18,587 women, with 17,842 women included in final analyses. There were no statistically significant differences between women who received calcium supplementation and those who did not in terms of reducing preterm births less than 37 weeks' gestation (risk ratio (RR) 0.86, 95% confidence interval (CI) 0.70 to 1.05; 13 studies, 16,139 women; random-effects model) or less than 34 weeks' gestation (RR 1.04, 95% CI 0.80 to 1.36; four trials, 5669). Most studies were of low risk of bias. We conducted sensitivity analysis for the outcome of preterm birth less than 37 weeks by removing two trials with unclear risk of bias for allocation concealment; the results then favoured treatment with calcium supplementation (RR 0.80, 95% CI 0.65 to 0.99; 11 trials, 15,379 women). There was no significant difference in infant low birthweight between the two treatment groups (RR 0.93, 95% CI 0.81 to 1.07; six trials, 14,162 infants; random-effects model). However, when compared to the control group, women in the calcium supplementation group gave birth to slightly heavier birthweight infants (mean difference 56.40, 95% CI 13.55 to 99.25; 21 trials, 9202 women; random-effects model).Three outcomes were chosen for assessment with the GRADE software: preterm birth less than 37 weeks; preterm birth less than 34 weeks; and low birthweight less than 2500 g. Evidence for these outcomes was assessed as of moderate quality.

AUTHORS' CONCLUSIONS

This review indicates that there are no clear additional benefits to calcium supplementation in prevention of preterm birth or low infant birthweight. While there was a statistically significant difference of 56 g identified in mean infant birthweight, there was significant heterogeneity identified, and the clinical significance of this difference is uncertain.

Infants at risk of cerebral palsy: a systematic review of outcomes used in Cochrane studies of pregnancy, childbirth and neonatology

OBJECTIVE

To systematically review meta-analyses (MAs) and randomised controlled trials (RCTs) of interventions for infants at risk of cerebral palsy (CP), to determine if consensus exists in study end-points.

METHODS

MAs within the "Neonatal" and "Pregnancy and Childbirth" Review Groups in Cochrane Database of Systematic Reviews (to June 2011) were included if they contained risk factors for CP as a study end-point, and were either published in 2010 or 2011 or cited >20 times in Sciverse Scopus. Up to 20 RCTs from each MA were included. Outcome measures, definitions and cut-points for ordinal groupings were extracted from MAs and RCTs and frequencies calculated.

RESULTS

Twenty-two MAs and 165 RCTs were appraised. High consistency existed in types of outcome domains listed as important in MAs. For 10/16 most frequently cited outcome domains, <50% of RCTs contributed data for meta-analyses. Low consistency in outcome definitions, measures, cut-points in RCTs and long-term follow-up prohibited data aggregation.

CONCLUSIONS

Variation in outcome measurement and long-term follow up has hampered the ability of RCTs to contribute data on important outcomes for CP, resulting in lost opportunities to measure the impact of maternal and neonatal interventions. There is an urgent need for and long-term follow up of these interventions and an agreed set of standardised and clinically relevant common data elements for study end-points.

Calcium supplementation during pregnancy for preventing hypertensive disorders and related problems

BACKGROUND

Pre-eclampsia and eclampsia are common causes of serious morbidity and death. Calcium supplementation may reduce the risk of pre-eclampsia, and may help to prevent preterm birth.

OBJECTIVES

To assess the effects of calcium supplementation during pregnancy on hypertensive disorders of pregnancy and related maternal and child outcomes.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (28 March 2013) and contacted study authors for more data where possible. We updated the search in May 2014 and added the results to the 'Awaiting Classification' section of the review.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing high-dose (at least 1 g daily of calcium) or low-dose calcium supplementation during pregnancy with placebo or no calcium.

DATA COLLECTION AND ANALYSIS

We assessed eligibility and trial quality, extracted and double-entered data.

MAIN RESULTS

High-dose calcium supplementation (≥1 g/day)We included 14 studies in the review, however one study contributed no data. We included 13 high-quality studies in our meta-analyses (15,730 women). The average risk of high blood pressure (BP) was reduced with calcium supplementation compared with placebo (12 trials, 15,470 women: risk ratio (RR) 0.65, 95% confidence interval (CI) 0.53 to 0.81; I² = 74%). There was also a significant reduction in the risk of pre-eclampsia associated with calcium supplementation (13 trials, 15,730 women: RR 0.45, 95% CI 0.31 to 0.65; I² = 70%). The effect was greatest for women with low calcium diets (eight trials, 10,678 women: average RR 0.36, 95% CI 0.20 to 0.65; I² = 76%) and women at high risk of pre-eclampsia (five trials, 587 women: average RR 0.22, 95% CI 0.12 to 0.42; I² = 0%). These data should be interpreted with caution because of the possibility of small-study effect or publication bias.The composite outcome maternal death or serious morbidity was reduced (four trials, 9732 women; RR 0.80, 95% CI 0.65 to 0.97; I² = 0%). Maternal deaths were not significantly different (one trial of 8312 women: calcium group one death versus placebo group six deaths). There was an anomalous increase in the risk of HELLP (haemolysis, elevated liver enzymes and low platelets) syndrome (two trials, 12,901 women: RR 2.67, 95% CI 1.05 to 6.82; I² = 0%) in the calcium group, however, the absolute number of events was low (16 versus six).The average risk of preterm birth was reduced in the calcium group (11 trials, 15,275 women: RR 0.76, 95% CI 0.60 to 0.97; I² = 60%) and amongst women at high risk of developing pre-eclampsia (four trials, 568 women: average RR 0.45, 95% CI 0.24 to 0.83; I² = 60%), but no significant reduction in neonatal high care admission. There was no overall effect on the risk of stillbirth or infant death before discharge from hospital (11 trials 15,665 babies: RR 0.90, 95% CI 0.74 to 1.09; I² = 0%).One study showed a reduction in childhood systolic BP greater than 95th percentile among children exposed to calcium supplementation in utero (514 children: RR 0.59, 95% CI 0.39 to 0.91). In a subset of these children, dental caries at 12 years old was also reduced (195 children, RR 0.73, 95% CI 0.62 to 0.87). Low-dose calcium supplementation (< 1 g/day)We included 10 trials (2234 women) that evaluated low-dose supplementation with calcium alone (4) or in association with vitamin D (3), linoleic acid (2), or antioxidants (1). Most studies recruited women at high risk for pre-eclampsia, and were at high risk of bias, thus the results should be interpreted with caution. Supplementation with low doses of calcium significantly reduced the risk of pre-eclampsia (RR 0.38, 95% CI 0.28 to 0.52; I² = 0%). There was also a reduction in hypertension, low birthweight and neonatal intensive care unit admission.

AUTHORS' CONCLUSIONS

Calcium supplementation (≥ 1 g/day) is associated with a significant reduction in the risk of pre-eclampsia, particularly for women with low calcium diets. The treatment effect may be overestimated due to small-study effects or publication bias. It also reduces preterm birth and the occurrence of the composite outcome 'maternal death or serious morbidity'. We considered these benefits to outweigh the increased risk of HELLP syndrome, which was small in absolute numbers. The World Health Organization recommends calcium 1.5 g to 2 g daily for pregnant women with low dietary calcium intake.The limited evidence on low-dose calcium supplementation suggests a reduction in pre-eclampsia, but needs to be confirmed by larger, high-quality trials. Pending such results, in settings of low dietary calcium where high-dose supplementation is not feasible, the option of lower-dose supplements (500 to 600 mg/day) might be considered in preference to no supplementation.

Survey of calcium supplementation to prevent preeclampsia: the gap between evidence and practice in Brazil

BACKGROUND

Preeclampsia is a major cause of maternal and perinatal morbidity and mortality worldwide and especially in Latin America. High quality evidence indicates that calcium supplementation during pregnancy significantly reduces the incidence of preeclampsia and its consequences, including severe maternal morbidity and death. Few studies have assessed the implementation of this intervention in clinical practice. The study aimed to assess the proportion of pregnant women who received calcium supplements in Brazilian public antenatal care clinics.

METHODS

This cross-sectional study interviewed women waiting for antenatal care visits in 9 public clinics in 4 Brazilian cities in 2010-2012. Trained interviewers used a standardized anonymous questionnaire to collect socio demographic and obstetric data, information on ingestion of dairy products and on prescriptions received during current pregnancy.

RESULTS

A total of 788 valid questionnaires were analyzed. Participants were young (mean age 25.9), mostly multiparous (71.3%) and in the 2nd or 3rd trimesters of pregnancy at the time of interview (87.6%). Only 5.1% (40/788) had received a prescription for calcium supplements. Based on their reported ingestion of dairy products, the mean daily dietary calcium intake of the participants was 210 (+ 265) mg/day and over 90% consumed less than 1 g of calcium/day.

CONCLUSIONS

Despite good quality evidence indicating the benefits of this practice especially for women with low calcium diets, less than 6% of a sample of women receiving antenatal care in Brazilian public clinics received a prescription for calcium supplements. There is an urgent need to upscale the implementation of this life-saving intervention.

Long-term child follow-up after large obstetric randomised controlled trials for the evaluation of perinatal interventions: a systematic review of the literature

BACKGROUND

Although the hope is that many perinatal interventions are performed with an ultimate aim to improve the long-term health and development of the child, long-term outcome is rarely used as a primary end-point in perinatal randomised controlled trials (RCTs).

OBJECTIVE

To evaluate how often and with which tools long-term follow-up is performed after large obstetric RCTs.

SEARCH STRATEGY

We searched the Cochrane Library for Cochrane reviews published by the Cochrane Pregnancy and Childbirth Group for reviews on interventions that aimed to improve neonatal outcome. Selection criteria  Reviews on perinatal interventions that were not performed to improve the condition of the neonate were excluded. We limited our review to RCTs with more than 350 participating women. For each included study, we checked in Web of Science as to whether the researchers had reported on follow-up in subsequent publications.

DATA COLLECTION AND ANALYSIS

Relevant information was extracted from these RCTs by two reviewers using a predefined data collection sheet. All information was analysed using SPSS 17.0 (SPSS Inc., Chicago, IL, USA).

MAIN RESULTS

We studied 212 reviews including 1837 RCTs on perinatal interventions, 249 (14%) of which included 350 participants. Only 40 of 249 RCTs (16%) followed the children after discharge from the hospital to evaluate the effect of a specific perinatal intervention. The number of RCTs with long-term follow-up remained stable, with 10 of 67 RCTs (15%) reporting follow-up before 1990, 17 of 115 (15%) between 1990 and 2000, and 13 of 67 (19%) after 2000 (P = 0.68).

CONCLUSIONS

Only a small minority of large perinatal RCTs report the long-term follow-up of the child. Future obstetric RCTs should consider performing long-term follow-up at the start of the trial.

Serum levels of zinc, calcium, and iron are associated with the risk of preeclampsia in pregnant women

Evidence indicates that various elements, including antioxidant minerals, might play an important role in preeclampsia (PE). This study was carried out to investigate the relationship between serum mineral levelsof zinc, calcium, iron, and selenium and the risk of preeclampsia in Korean women. Twenty-nine normal controls and 30 women with preeclampsia were recruited for the study. Preeclampsia was defined as having high blood pressure (≥ 140/90 mm Hg after 20 weeks gestation) and proteinuria (≥300 mg/24 hours). Serum mineral content was determined by instrumental neutron activation analysis. Serum zinc (P < .0001) and calcium (P = .0188) levels were lower in women with preeclampsia than those of normal women, while serum iron was significantly higher in women with preeclampsia (P = .0045). The odds ratio for preeclampsia was lower in women with higher serum zinc levels than those with lower levels after adjustment for age, height, and weight before delivery (P < .0001). The adjusted odds ratio for preeclampsia also decreased across tertiles of serum calcium concentration (P = .0452). However, there was an increased adjusted odds ratio for preeclampsia across tertiles of serum iron level (P = .0104). These results suggest that levels of serum minerals such as zinc, calcium, and iron may be associated with the risk of preeclampsia in Korean pregnant women.

Calcium supplementation and prevention of preeclampsia: a meta-analysis

BACKGROUND

Since the early 1980s, epidemiological evidence has suggested a connection between low calcium intake and preeclampsia The purpose of this meta-analysis is to summarize current evidence regarding calcium supplementation during pregnancy in predicting preeclampsia and associated maternal-fetal complications.

METHODS

Literature revision of all RCT (random allocation of calcium versus placebo) available in MEDLINE/PUBMED up to 2/29/2012 regarding calcium supplementation during pregnancy for preventing preeclampsia. We used the Mantel-Haenszel's Method for four subgroup of patients: Adequate calcium intake; Low calcium intake; Low risk of preeclampsia; High risk of preeclampsia. We considered p < 0.05 as significant.

RESULTS

There is no consensus in Literature about: (1) the efficacy of calcium supplementation in the prevention of preeclampsia, (2) other/adverse/long-term effects of calcium supplementation in pregnancy.

CONCLUSIONS

Preeclampsia is likely to be a multifactorial disease. However, inadequate calcium intake represents a factor associated with an increased incidence of hypertensive disease. The results of our meta-analysis demonstrate that the additional intake of calcium during pregnancy is an effective measure to reduce the incidence of preeclampsia, especially in populations at high risk of preeclampsia due to ethnicity, gender, age, high BMI and in those with low baseline calcium intake.

Effects of calcium supplementation during pregnancy on maternal, fetal and birth outcomes

Gestational hypertensive disorders are the second leading cause of maternal death worldwide. Epidemiological and clinical studies have shown that an inverse relationship exists between calcium intake and development of hypertension in pregnancy. The purpose of this review was to evaluate preventive effect of calcium supplementation during pregnancy on gestational hypertensive disorders and related maternal and neonatal morbidity and mortality. A literature search was carried out on PubMed, WHOLIS, PAHO and Cochrane Library. Only randomised trials were included in the review. Data were extracted into a standardised Excel sheet. Primary outcomes were pre-eclampsia, preterm birth and birthweight. Other neonatal outcomes such as neonatal mortality, small-for-gestational age and low birthweight were also evaluated. A total of 15 randomised controlled trials were included in this review. Pooled analysis showed that calcium supplementation during pregnancy reduced risk of pre-eclampsia by 52% [relative risk (RR) 0.48; 95% confidence interval (CI) 0.34, 0.67] and that of severe pre-eclampsia by 25% (RR 0.75 [95% CI 0.57, 0.98]). There was no effect on incidence of eclampsia (RR 0.73 [95% CI 0.41, 1.27]). There was a significant reduction for risk of maternal mortality/severe morbidity (RR 0.80 [95% CI 0.65, 0.97]). Calcium supplementation during pregnancy was also associated with a significant reduction in risk of pre-term birth (RR 0.76 [95% CI 0.60, 0.97]). There was an extra gain of 85 g in the intervention group compared with control (mean difference 85 g [95% CI 37, 133]). There was no effect of calcium supplementation on perinatal mortality (RR 0.90 [95% CI 0.74, 1.09]). There was a statistically non-significant increased risk of urolithiasis in the intervention group compared with control (RR 1.52 [95% CI 0.06, 40.67]). In conclusion, calcium supplementation during pregnancy is associated with a reduction in risk of gestational hypertensive disorders and pre-term birth and an increase in birthweight. There is no increased risk of kidney stones.

Family medicine obstetrics: pregnancy and nutrition

This article discusses pregnancy and nutrition in 3 main timeframes, the prepregnancy nutritional health evaluation, nutrition during pregnancy, and nutrition during the puerperium, and also includes comments on nutrition and lactation. This article begins with a brief review of the risks of obesity (increased body mass index [BMI]) and anorexia (decreased BMI), with special attention to these undesired conditions during pregnancy, followed by a section on nutrients other than calories. Information on body weight, minerals, and vitamins during pregnancy is reviewed. This article ends with information on nutrition in the postpartum period.

Calcium supplementation (other than for preventing or treating hypertension) for improving pregnancy and infant outcomes

BACKGROUND

Maternal nutrition during pregnancy is known to have an effect on fetal growth and development. It is recommended that women increase their calcium intake during pregnancy and lactation, although the recommended dosage varies among professionals. Currently, there is no consensus on the role of routine calcium supplementation for pregnant women other than for preventing or treating hypertension.

OBJECTIVES

To determine the effect of calcium supplementation on maternal, fetal and neonatal outcomes (other than for preventing or treating hypertension) as well as any possible side effects.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (17 March 2011).

SELECTION CRITERIA

We considered all published, unpublished and ongoing randomised controlled trials (RCTs) comparing maternal, fetal and neonatal outcomes in pregnant women who received calcium supplementation versus placebo or no treatment. We excluded quasi- and pseudo-RCTs.

DATA COLLECTION AND ANALYSIS

Two review authors identified studies for inclusion and extracted the data. Two review authors performed data analysis.

MAIN RESULTS

This review includes data from 21 studies (involving 16,602 women). There were no statistically significant differences between women who received calcium supplementation and those who did not in terms of reducing preterm births (less than 37 weeks' gestation) (risk ratio (RR) 0.90; 95% confidence interval (CI) 0.73 to 1.11; 12 studies, 15615 women; random-effects model) and also in less than 34 weeks' gestation (RR 1.11; 95% CI 0.84 to 1.46; three trials, 5145 women). There was no significant difference in infant low birth weight between the two groups (RR 0.91; 95% CI 0.72 to 1.16; four trials, 13449 infants; random-effects). However, compared to the control group, women in the calcium supplementation group gave birth to slightly heavier birth weight infants (mean difference (MD) 64.66 g; 95% CI 15.75 to 113.58; 19 trials, 8287 women; random-effects).

AUTHORS' CONCLUSIONS

Calcium supplementation is associated with a significant protective benefit in the prevention of pre-eclampsia, and should be used for this indication according to a previous review. This review indicates that there are no additional benefits for calcium supplementation in prevention of preterm birth or low infant birth weight. While there was a statistically significant difference of 80 g identified in mean infant birth weight, there was significant heterogeneity identified, and the clinical significance of this difference is uncertain.

Maternal plasma concentrations of angiogenic/anti-angiogenic factors are of prognostic value in patients presenting to the obstetrical triage area with the suspicion of preeclampsia

OBJECTIVE

To determine whether maternal plasma concentrations of placental growth factor (PlGF), soluble endoglin (sEng), soluble vascular endothelial growth factor receptor-1 (sVEGFR-1) and -2 could identify patients at risk for developing preeclampsia (PE) requiring preterm delivery.

STUDY DESIGN

Patients presenting with the diagnosis "rule out PE" to the obstetrical triage area of our hospital at <37 weeks of gestation (n = 87) were included in this study. Delivery outcomes were used to classify patients into four groups: I) patients without PE or those with gestational hypertension (GHTN) or chronic hypertension (CHTN) who subsequently developed PE at term (n = 19); II): mild PE who delivered at term (n = 15); III): mild disease (mild PE, GHTN, CHTN) who subsequently developed severe PE requiring preterm delivery (n = 26); and IV): diagnosis of severe PE (n = 27). Plasma concentrations of PlGF, sEng, sVEGFR-1 and -2 were determined at the time of presentation by ELISA. Reference ranges for analytes were constructed by quantile regression in our laboratory (n = 180; 1046 samples). Comparisons among groups were performed using multiples of the median (MoM) and parametric statistics after log transformation. Receiver operating characteristic curves, logistic regression and survival analysis were employed for analysis.

RESULTS

The mean MoM plasma concentration of PlGF/sVEGFR-1, PlGF/sEng, PlGF, sVEGFR-1 and -2, and sEng in Group III was significantly different from Group II (all p < 0.05). A plasma concentration of PlGF/sVEGFR-1 ≤ 0.05 MoM or PlGF/sEng ≤0.07 MoM had the highest likelihood ratio of a positive test (8.3, 95% CI 2.8-25 and 8.6, 95% CI 2.9-25, respectively), while that of PlGF ≤0.396 MoM had the lowest likelihood ratio of a negative test (0.08, 95% CI 0.03-0.25). The association between low plasma concentrations of PlGF/sVEGFR-1 (≤0.05 MoM) as well as that of PlGF/sEng (≤0.07 MoM) and the development of severe PE remained significant after adjusting for gestational age at presentation, average systolic and diastolic blood pressure, and a history of chronic hypertension [adjusted odds ratio (OR) = 27 (95% CI 6.4-109) and adjusted OR 30 (95% CI 6.9-126), respectively]. Among patients who presented <34 weeks gestation (n = 59), a plasma concentration of PlGF/sVEGFR-1 < 0.033 MoM identified patients who delivered within 2 weeks because of PE with a sensitivity of 93% (25/27) and a specificity of 78% (25/32). This cut-off was associated with a shorter interval-to-delivery due to PE [hazard ratio = 6 (95% CI 2.5-14.6)].

CONCLUSIONS

Plasma concentrations of angiogenic/anti-angiogenic factors are of prognostic value in the obstetrical triage area. These observations support the value of these biomarkers in the clinical setting for the identification of the patient at risk for disease progression requiring preterm delivery.

Preeclampsia: pathophysiology and implications for care

Nurses are increasingly encountering pregnant/postpartum women with hypertensive disorders of pregnancy, of which preeclampsia is one of the most common. The Joint Commission published a Sentinel Event Alert in 2010 on prevention of maternal death. This report notes that one of the 5 leading causes of pregnancy-related mortality between 1991 and 1997 was "hypertensive disorder." Preeclampsia presents significant risk to the health of the mother and the fetus. Clearly, nurses must understand the pathophysiology, assessment, management, recurrence risk, and long-term implications of preeclampsia to participate fully in a management plan that promotes safe patient care.

Stillbirths: the way forward in high-income countries

Stillbirth rates in high-income countries declined dramatically from about 1940, but this decline has slowed or stalled over recent times. The present variation in stillbirth rates across and within high-income countries indicates that further reduction in stillbirth is possible. Large disparities (linked to disadvantage such as poverty) in stillbirth rates need to be addressed by providing more educational opportunities and improving living conditions for women. Placental pathologies and infection associated with preterm birth are linked to a substantial proportion of stillbirths. The proportion of unexplained stillbirths associated with under investigation continues to impede efforts in stillbirth prevention. Overweight, obesity, and smoking are important modifiable risk factors for stillbirth, and advanced maternal age is also an increasingly prevalent risk factor. Intensified efforts are needed to ameliorate the effects of these factors on stillbirth rates. Culturally appropriate preconception care and quality antenatal care that is accessible to all women has the potential to reduce stillbirth rates in high-income countries. Implementation of national perinatal mortality audit programmes aimed at improving the quality of care could substantially reduce stillbirths. Better data on numbers and causes of stillbirth are needed, and international consensus on definition and classification related to stillbirth is a priority. All parents should be offered a thorough investigation including a high-quality autopsy and placental histopathology. Parent organisations are powerful change agents and could have an important role in raising awareness to prevent stillbirth. Future research must focus on screening and interventions to reduce antepartum stillbirth as a result of placental dysfunction. Identification of ways to reduce maternal overweight and obesity is a high priority for high-income countries.

Role of calcium supplementation during pregnancy in reducing risk of developing gestational hypertensive disorders: a meta-analysis of studies from developing countries

BACKGROUND

Hypertension in pregnancy stand alone or with proteinuria is one of the leading causes of maternal mortality and morbidity in the world. Epidemiological and clinical studies have shown that an inverse relationship exists between calcium intake and development of hypertension in pregnancy though the effect varies based on baseline calcium intake and pre-existing risk factors. The purpose of this review was to evaluate preventive effect of calcium supplementation during pregnancy on gestational hypertensive disorders and related maternal and neonatal mortality in developing countries.

METHODS

A literature search was carried out on PubMed, Cochrane Library and WHO regional databases. Data were extracted into a standardized excel sheet. Identified studies were graded based on strengths and limitations of studies. All the included studies were from developing countries. Meta-analyses were generated where data were available from more than one study for an outcome. Primary outcomes were maternal mortality, eclampsia, pre-eclampsia, and severe preeclampsia. Neonatal outcomes like neonatal mortality, preterm birth, small for gestational age and low birth weight were also evaluated. We followed standardized guidelines of Child Health Epidemiology Reference Group (CHERG) to generate estimates of effectiveness of calcium supplementation during pregnancy in reducing maternal and neonatal mortality in developing countries, for inclusion in the Lives Saved Tool (LiST).

RESULTS

Data from 10 randomized controlled trials were included in this review. Pooled analysis showed that calcium supplementation during pregnancy was associated with a significant reduction of 45% in risk of gestational hypertension [Relative risk (RR) 0.55; 95 % confidence interval (CI) 0.36-0.85] and 59% in the risk of pre-eclampsia [RR 0.41; 95 % CI 0.24-0.69] in developing countries. Calcium supplementation during pregnancy was also associated with a significant reduction in neonatal mortality [RR 0.70; 95 % CI 0.56-0.88] and risk of pre-term birth [RR 0.88, 95 % CI 0.78-0.99]. Recommendations for LiST for reduction in maternal mortality were based on risk reduction in gestational hypertensive related severe morbidity/mortality [RR 0.80; 95% CI 0.70-0.91] and that for neonatal mortality were based on risk reduction in all-cause neonatal mortality [RR 0.70; 95% CI 0.56-0.88].

CONCLUSION

Calcium supplementation during pregnancy is associated with a reduction in risk of gestational hypertension, pre-eclampsia neonatal mortality and pre-term birth in developing countries.

Calcium supplementation during pregnancy for preventing hypertensive disorders and related problems

BACKGROUND

Pre-eclampsia and eclampsia are common causes of serious morbidity and death. Calcium supplementation may reduce the risk of pre-eclampsia through a number of mechanisms, and may help to prevent preterm birth.

OBJECTIVES

To assess the effects of calcium supplementation during pregnancy on hypertensive disorders of pregnancy and related maternal and child outcomes.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (May 2010) and contacted study authors.

SELECTION CRITERIA

Randomised trials comparing at least 1 g daily of calcium during pregnancy with placebo.

DATA COLLECTION AND ANALYSIS

We assessed eligibility and trial quality, extracted and double-entered data.

MAIN RESULTS

We included 13 studies of good quality (involving 15,730 women). The average risk of high blood pressure was reduced with calcium supplementation rather than placebo (12 trials, 15,470 women: risk ratio (RR) 0.65, 95% confidence interval (CI) 0.53 to 0.81). There was also a reduction in the average risk of pre-eclampsia associated with calcium supplementation (13 trials, 15,730 women: RR 0.45, 95% CI 0.31 to 0.65). The effect was greatest for high-risk women (five trials, 587 women: RR 0.22, 95% CI 0.12 to 0.42), and those with low baseline calcium intake (eight trials, 10,678 women: RR 0.36, 95% CI 0.20 to 0.65).The average risk of preterm birth was reduced in the calcium group overall (11 trials, 15,275 women: RR 0.76, 95% CI 0.60 to 0.97) and amongst women at high risk of developing pre-eclampsia recruited to four small trials (568 women: RR 0.45, 95% CI 0.24 to 0.83).There was no overall effect on the risk of stillbirth or death before discharge from hospital (11 trials 15,665 babies; RR 0.90, 95% CI 0.74 to 1.09). The composite outcome maternal death or serious morbidity was reduced (four trials, 9732 women; RR 0.80, 95% CI 0.65 to 0.97). Most of the women in these trials were low risk and had a low calcium diet. Maternal deaths were reported in only one trial. One death occurred in the calcium group and six in the placebo group, a difference which was not statistically significant (RR 0.17, 95% CI 0.02 to 1.39).Blood pressure in childhood has been assessed in two studies, only one of which is currently included: childhood systolic blood pressure greater than 95th percentile was reduced (514 children: RR 0.59, 95% CI 0.39 to 0.91).

AUTHORS' CONCLUSIONS

Calcium supplementation appears to approximately halve the risk of pre-eclampsia, to reduce the risk of preterm birth and to reduce the rare occurrence of the composite outcome 'death or serious morbidity'. There were no other clear benefits, or harms.

Cryotherapy for HPV clearance in women with biopsy-confirmed cervical low-grade squamous intraepithelial lesions

OBJECTIVE

To compare the clearance rate of HPV infection among women aged older than 30 years with biopsy-confirmed cervical low-grade squamous intraepithelial lesions (LSIL) 1 year after cryotherapy with the spontaneous clearance rate (observation).

METHOD

HPV DNA typing by polymerase chain reaction and reverse line blot hybridization were used to identify 14 high-risk types and 23 low-risk types. HPV DNA sequencing was also used for other types.

RESULT

Between December 2007 and March 2009, 100 women were recruited to the study and 60 cases had positive results on HPV testing. Twenty-nine patients were randomly allocated to the cryotherapy group and 31 to the observation group. At 1 year, 89.7% (26/29; 95% CI, 78.6-100%) of the cryotherapy group and 90.3% (28/31; 95% CI, 79.9-100%) of the observation group had negative results on HPV testing (0.6% difference; 95% CI, -15.8 to 14.6%, P=0.94).

CONCLUSION

Cryotherapy failed to increase the clearance of prevalent HPV infections among women with LSIL, although in both arms the clearance rates were above 80%. However, in coupling with visual inspection with acetic acid as a single visit approach, its effect on prevention of HSIL and cervical cancer is still promising. Therefore, cryotherapy should not be withdrawn from such programs.

Vascular and cellular calcium in normal and hypertensive pregnancy

Normal pregnancy is associated with significant hemodynamic changes in the cardiovascular system in order to meet the metabolic demands of mother and fetus. These changes include increased cardiac output, decreased vascular resistance, and vascular remodeling in the uterine and systemic circulation. Preeclampsia (PE) is a major complication of pregnancy characterized by proteinuria and hypertension. Several risk factors have been implicated in the pathogenesis of PE including genetic and dietary factors. Ca2+ is an essential dietary element and an important regulator of many cellular processes including vascular function. The importance of adequate dietary Ca2+ intake during pregnancy is supported by many studies. Pregnancy-associated changes in Ca2+ metabolism and plasma Ca2+ have been observed. During pregnancy, changes in intracellular free Ca2+ concentration ([Ca2+](i)) have been described in red blood cells, platelets and immune cells. Also, during pregnancy, an increase in [Ca2+](i) in endothelial cells (EC) stimulates the production of vasodilator substances such as nitric oxide and prostacyclin. Normal pregnancy is also associated with decreased vascular smooth muscle (VSM) [Ca2+](i) and possibly the Ca2+-sensitization pathways of VSM contraction including protein kinase C, Rho-kinase, and mitogen-activated protein kinase. Ca2+-dependent matrix metalloproteinases could also promote extracellular matrix degradation and vascular remodeling during pregnancy. Disruption in the balance between dietary, plasma and vascular cell Ca2+ may be responsible for some of the manifestation of PE including procoagulation, decreased vasodilation, and increased vasoconstriction and vascular resistance. The potential benefits of Ca2+ supplements during pregnancy, and the use of modulators of vascular Ca2+ to reduce the manifestations of PE in susceptible women remain an important area for experimental and clinical research.

Calcium supplementation for the prevention of pre-eclampsia

OBJECTIVE

To study the effect of calcium supplementation during pregnancy on blood pressure and maternal and neonatal outcomes.

METHOD

A total of 524 healthy primigravidas with a blood pressure less than 140/90 mm Hg were randomly assigned between the 12th and 25th weeks to receive 2 g of elemental calcium or placebo and were followed-up until delivery.

RESULTS

The incidence of pre-eclampsia was significantly less in the calcium than in the placebo group (4.0% vs 12.0%; odds ratio [OR], 0.31; 95% confidence interval [CI], 0.15-0.63); the mean systolic and diastolic blood pressures at study completion were different in the calcium and placebo group (P=0.007 and P=0.02). The risk for preterm delivery was less in the calcium (7.0%) than in the placebo (12.7%) group (OR, 0.51; 95% CI, 0.28-0.93). The mean baseline calcium intake was 313.83+/-203.25 mg/day (range, 85.71-910.71 mg/day), which is lower than the recommended dietary intake of 1000 mg, and the 24-hour urinary calcium excretion was 130.82+/-67.44 mg/dL (range, 40.5-387 mg/dL).

CONCLUSION

Calcium supplementation appears to reduce the occurrence of pre-eclampsia and preterm delivery in primigravidas who have a daily dietary calcium intake less than the recommended dietary allowances.

Conference on "Multidisciplinary approaches to nutritional problems". Postgraduate Symposium. Exploiting dietary supplementation trials to assess the impact of the prenatal environment on CVD risk

Animal studies have demonstrated that altering the maternal diet during pregnancy affects offspring disease risk. Data from human subjects on the early-life determinants of disease have been derived primarily from birth-weight associations; studies of the impact of the maternal diet are scarce and inconsistent. Investigating CVD risk factors in the offspring of women who have participated in maternal supplementation trials provides a useful resource in this research field, by virtue of employing an experimental design (as compared with observational studies). To date, follow-up studies have been published only for a small number of trials; these trials include the impact of maternal protein-energy, multiple-micronutrient and Ca supplementation on offspring disease risk. In Nepal maternal micronutrient supplementation has been shown to be associated with lower offspring systolic blood pressure at 2 years of age. Data from Guatemala on a pre- and postnatal protein-energy community intervention have suggested long-term improvements in fasting glucose and body composition but not in blood pressure. In The Gambia no association has been found between prenatal protein-energy supplementation and markers of CVD risk including body composition, blood pressure and fasting glucose and insulin in childhood and adolescence. Little evidence of an effect of maternal Ca supplementation on offspring blood pressure has been demonstrated in four trials, although the risk of high systolic blood pressure was found to be reduced in one trial. The present paper reviews the current evidence relating maternal nutritional supplementation during pregnancy to offspring CVD risk and explores the potential explanations for the lack of association.

Supplemental Calcium and Risk Reduction of Hypertension, Pregnancy-Induced Hypertension, and Preeclampsia: An Evidence-Based Review by the US Food and Drug Administration

The labeling of health claims that meet the significant scientific agreement (SSA) standard (authorized health claims) and qualified health claims on conventional foods and dietary supplements requires premarket approval by the US Food and Drug Administration (FDA). FDA conducts an evidence-based review to determine whether there is sufficient evidence to support an authorized or qualified health claim. An evidence-based review was conducted on the human intervention and observational studies evaluating the role of supplemental calcium in reducing the risk of hypertension, pregnancy-induced hypertension, and preeclampsia. This review provides FDA's evaluation of the current scientific evidence on the role of supplemental calcium in reducing the risk of these three end points. Based on this evidence-based review, the agency concluded that the relationship between calcium and risk of hypertension is inconsistent and inconclusive, and the relationship between calcium and risk of pregnancy-induced hypertension and preeclampsia is highly unlikely.