Limited evidence for calcium supplementation in preeclampsia prevention: a meta-analysis and systematic review

Dietary factors that affect the risk of pre-eclampsia

Pre-eclampsia affects 3%-5% of pregnant women worldwide and is associated with a range of adverse maternal and fetal outcomes, including maternal and/or fetal death. It particularly affects those with chronic hypertension, pregestational diabetes mellitus or a family history of pre-eclampsia. Other than early delivery of the fetus, there is no cure for pre-eclampsia. Since diet or dietary supplements may affect the risk, we have carried out an up-to-date, narrative literature review to assess the relationship between nutrition and pre-eclampsia. Several nutrients and dietary factors previously believed to be implicated in the risk of pre-eclampsia have now been shown to have no effect on risk; these include vitamins C and E, magnesium, salt, ω-3 long-chain polyunsaturated fatty acids (fish oils) and zinc. Body mass index is proportionally correlated with pre-eclampsia risk, therefore women should aim for a healthy pre-pregnancy body weight and avoid excessive gestational and interpregnancy weight gain. The association between the risk and progression of the pathophysiology of pre-eclampsia may explain the apparent benefit of dietary modifications resulting from increased consumption of fruits and vegetables (≥400 g/day), plant-based foods and vegetable oils and a limited intake of foods high in fat, sugar and salt. Consuming a high-fibre diet (25-30 g/day) may attenuate dyslipidaemia and reduce blood pressure and inflammation. Other key nutrients that may mitigate the risk include increased calcium intake, a daily multivitamin/mineral supplement and an adequate vitamin D status. For those with a low selenium intake (such as those living in Europe), fish/seafood intake could be increased to improve selenium intake or selenium could be supplemented in the recommended multivitamin/mineral supplement. Milk-based probiotics have also been found to be beneficial in pregnant women at risk. Our recommendations are summarised in a table of guidance for women at particular risk of developing pre-eclampsia.

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).

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.

The association between calcium supplement and preeclampsia and gestational hypertension: a systematic review and meta-analysis of randomized trials

OBJECTIVES

The purpose of this study is to investigate whether calcium supplement with or without other drugs could reduce the risk of preeclampsia and gestational hypertension based on existed evidence, and to clarify whether there is discrepant effect among different population and using different dose.

METHODS

PubMed, Cochrane library, and EMBASE database were searched. Two authors independently screened all records and extracted data. The meta-analysis was performed to calculate risk ratios and 95% CIs using random-effects models.

RESULTS

27 studies, with 28 492 pregnant women were included. The results showed calcium supplement was associated with lower incidence of preeclampsia (RR 0.51, 95% CI: 0.40 to 0.64) and gestational hypertension (RR 0.70, 95% CI: 0.60 to 0.82). Sub-analyses revealed high-dose (1.2-2 g/day), moderate-dose (0.6-1.2 g/day), and low-dose (<0.6 g/day) of calcium supplement could reduce the risk of preeclampsia. For gestational hypertension, only high dose and moderate dose groups were associated with reducing the risk of gestational hypertension. However, we could draw a conclusion which does group was the most protective, as we were unable to directly compare the effects of different doses.

CONCLUSIONS

This study indicated calcium supplementation might decrease the risk of preeclampsia and gestational hypertension. And results of subgroups analyses enhanced our confidence to the protective effect of calcium supplementation. However, further studies with direct comparison of different dose of calcium supplementation are needed to explore the ideal dose of calcium supplementation to prevent preeclampsia and gestational hypertension.

Effect of Self-care Before and During Pregnancy to Prevention and Control Preeclampsia in High-risk Women

Our aims to examine the factors influencing self-care for the prevention and control of preeclampsia in high-risk women. The current study is a review where the researcher browsed the available databases such as PubMed, Cochrane, Medline, Google Scholar, Medscape, and relevant research published between 1980 and 2016 were studied. To search for articles, relevant Medical Subject Heading keywords were first determined (Self-care, preeclampsia, prevention.) A total of 350 related articles were first selected, and the findings of 70 were used to compile the present article. The results of the study were classified under two general categories, including (1). Counseling and screening strategies and (2) self-care strategies for the prevention and control of preeclampsia in high-risk women. Screening women at risk for preeclampsia include measures such as measuring their blood pressure, checking for signs of depression, testing for thrombosis, taking a history of preeclampsia, providing preconception counseling about the appropriate age, time of pregnancy, and encouraging weight loss in obese women. This review showed a positive relationship between knowledge about self-care for preeclampsia and its control. The factors influencing preeclampsia self-care include making lifestyle changes, having a healthy diet, learning stress management, performing exercise and physical activities, taking antioxidants, dietary supplements, and calcium and adherence to aspirin and heparin regimens. There is a positive relationship between preconception counseling, screening women at risk for preeclampsia, self-care for the prevention, and control of preeclampsia.

(1) Tweetable abstract self-care in high-risk women is strongly associated with prevention and control of preeclampsia.

Investigation of elevation as a risk factor for hypertensive disorders of pregnancy among Colorado women between 2007 and 2015

OBJECTIVE

The purpose of this study is to determine the association between high elevation and hypertensive disorders of pregnancy (HDP).

METHODS

Retrospective cohort study using Colorado birth certificate data to compare HDP at high (≥8,000 ft), moderate (4,501-7,999 ft), or low (≤4,500 ft) elevation using logistic regression.

RESULTS

Among the cohort (n = 314,431), 3.4% of women developed a HDP. High or moderate elevation was not significantly associated with HDP relative to low elevation (adjusted odds ratio [aOR] 1.16, 95% confidence interval [CI] 0.93-1.43; aOR 1.14, 95% CI 0.98-1.31, respectively).

CONCLUSION

Women living at high or moderate elevation do not have higher odds of HDP.

Nutritional approach to preeclampsia prevention

PURPOSE OF REVIEW

Although not fully understood, the physiopathology of preeclampsia is thought to involve an abnormal placentation, diffuse endothelial cell dysfunction and increased systemic inflammation. As micronutrients play a key role in placental endothelial function, oxidative stress and expression of angiogenic factors, periconceptional micronutrient supplementation has been proposed to reduce the risk of preeclampsia. However, recent studies reported conflicting results.

RECENT FINDINGS

Calcium intake (>1 g/day) may reduce the risk of preeclampsia in women with low-calcium diet. Data from recently updated Cochrane reviews did not support routine supplementation of vitamins C, E or D for either the prevention or treatment of preeclampsia. Evidences are also poor to support zinc or folic acid supplementation for preeclampsia prevention. Dark chocolate, flavonoid-rich food, and long-chain polyunsaturated fatty acids might also be candidates for prevention of preeclampsia.

SUMMARY

Through antioxidant, anti-inflammatory or vasoactive proprieties, micronutrients are good candidates for preeclampsia prevention. Calcium supplementation is recommended to prevent preeclampsia in women with low-calcium intake. Despite positive clinical and in-vitro data, strong evidence to support periconceptional supplementation of other micronutrients for preeclampsia risk-reduction is still lacking. Further studies are also needed to evaluate the benefit of nutritional supplementation such as chocolate and long-chain polyunsaturated fatty acids.

Assessment of dietary intake and mineral status in pregnant women

Purpose

To evaluate the dietary intake of pregnant women and their nutritional status of Ca, Mg, Fe, Zn, and Cu, as the nutritional status of pregnant women is an important factor for the proper progression of a pregnancy and the development and health of the foetus.

Methods

The study was conducted on 108 pregnant women ages 18–42, at 6–32 weeks of gestation. We used a questionnaire and a 24-h recall nutrition interview. Hair samples were taken for testing and the level of each mineral was assessed using atomic absorption spectrometry. The results were analysed using the Dietetyk and Statistica 10 software.

Results

Low levels of Fe, Zn, Ca, Mg, vitamin D, and folic acid intake were seen in the pregnant women, with the use of dietary supplements significantly increasing their intake of Fe, Zn, and folic acid. The concentration of zinc and magnesium in the women’s hair was shown to be affected by their age and, in the case of magnesium, by the week of pregnancy.

Conclusions

It was observed that the diet of pregnant women is characterised by low levels of Fe, Zn, Ca, Mg, vitamin D, and folic acid. Dietary supplementation with vitamins and minerals significantly increases the daily Fe and folic acid intake in pregnant women. The concentration of Zn and Mg in hair depends on the age of pregnant women and Mg level in the hair of women decreases during pregnancy.

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.

Altered metabolic homeostasis between vitamin D and long chain polyunsaturated fatty acids in preeclampsia

Sub-optimal maternal nutrition may result in pregnancy complications like preeclampsia. Preeclampsia is known to be of placental origin and a major cause of maternal morbidity and mortality worldwide. Our earlier studies suggest that altered metabolism of folic acid, vitamin B₁₂ and long chain polyunsaturated fatty acid (LCPUFAs) in the one carbon cycle increases homocysteine levels in preeclampsia. Recent reports indicate that vitamin D deficiency may also have a role in preeclampsia, although the mechanisms are unclear. A disturbed one carbon cycle can influence methylation patterns of various genes involved in placental development. Altered expression of cystathionine beta synthase (CBS) gene can result in hyperhomocystenemia. Higher homocysteine levels are known to increase reactive oxygen species (ROS) production which in turn leads to increased expression of phospholipase A2 (PLA2) and cyclooxygenase-2 (COX-2). Higher expression of PLA2 and COX-2 can influence the release of arachidonic acid (AA) from membrane phospholipid and result in increased conversion to thromboxane. Vitamin D [1,25(OH)₂D₃] is known to induce the CBS gene expression while it can suppress the oxidative stress-induced COX-2 up-regulation and thromboxane production. Based on this, we propose a novel hypothesis that a disturbed vitamin D and LCPUFA metabolism influence the regulation of the one carbon cycle which will trigger inflammation through oxidative stress in preeclampsia. This may lead to altered feto-placental growth and development in preeclampsia.

Community Pharmacists' Views and Practices Regarding Natural Health Products Sold in Community Pharmacies

BACKGROUND

Reports of regulatory and evidentiary gaps have raised concerns about the marketing and use of natural health products (NHPs). The majority of NHPs offered for sale are purchased at a community pharmacy and pharmacists are "front-line" health professionals involved in the marketing and provision of NHPs. To date, the involvement of pharmacists in pharmacy care involving NHPs and the degree to which concerns over the safety, efficacy, marketing and regulation of NHPs are addressed in pharmacy care in Canada have not been studied.

METHODS

Using Qualtrics, a web-based data collection and analysis software, and a study instrument made up of fifteen (15) open-ended, closed and rating scale questions, we surveyed the attitudes and practices of 403 community pharmacists in the Canadian province of Alberta regarding NHPs offered for sale in community pharmacies.

RESULTS

The majority of pharmacists surveyed (276; 68%) recommend NHPs to clients sometimes to very often. Vitamin D, calcium, multivitamins, prenatal vitamins, probiotics and fish oil and omega-3 fatty acids were the most frequently recommended NHPs. The most common indications for which NHPs are recommended include bone and musculoskeletal disorders, maintenance of general health, gastrointestinal disorders and pregnancy. Review articles published in the Pharmacist's Letter and Canadian Pharmacists Journal were the primary basis for recommending NHPs. The majority of pharmacists surveyed (339; 84%) recommend the use of NHPs concurrently with conventional drugs, while a significant number and proportion (125; 31%) recommend alternative use. Pharmacists in the study overwhelmingly reported providing counselling on NHPs to clients based on information obtained mainly from the Natural Medicines Comprehensive Database.

CONCLUSIONS

The study findings indicate a high prevalence of pharmacy care relating to NHPs among study participants. Although pharmacists' practices around NHPs are consistent with the existing licensing framework, we found some involvement in problematic practices that necessitate further research and potential policy scrutiny. The study also uncovered patterns of recommendations, including sources relied on in recommending NHPs and in providing counselling to patients, that raise concerns about the quality and credibility of NHP-related care provided to pharmacy patrons.

Perspectives on the design and methodology of periconceptional nutrient supplementation trials

Periconceptional supplementation could extend the period over which maternal and fetal nutrition is improved, but there are many challenges facing early-life intervention studies. Periconceptional trials differ from pregnancy supplementation trials, not only because of the very early or pre-gestational timing of nutrient exposure but also because they generate subsidiary information on participants who remain non-pregnant. The methodological challenges are more complex although, if well designed, they provide opportunities to evaluate concurrent hypotheses related to the health of non-pregnant women, especially nulliparous adolescents. This review examines the framework of published and ongoing randomised trial designs. Four cohorts typically arise from the periconceptional trial design--two of which are non-pregnant and two are pregnant--and this structure provides assessment options related to pre-pregnant, maternal, pregnancy and fetal outcomes. Conceptually the initial decision for single or micronutrient intervention is central--as is the choice of dosage and content--in order to establish a comparative framework across trials, improve standardisation, and facilitate interpretation of mechanistic hypotheses. Other trial features considered in the review include: measurement options for baseline and outcome assessments; adherence to long-term supplementation; sample size considerations in relation to duration of nutrient supplementation; cohort size for non-pregnant and pregnant cohorts as the latter is influenced by parity selection; integrating qualitative studies and data management issues. Emphasis is given to low resource settings where high infection rates and the possibility of nutrient-infection interactions may require appropriate safety monitoring. The focus is on pragmatic issues that may help investigators planning a periconceptional trial.

Reducing stillbirths in low-income countries

Worldwide, 98% of stillbirths occur in low-income countries (LIC), where stillbirth rates are ten-fold higher than in high-income countries (HIC). Although most HIC stillbirths occur prenatally, in LIC most stillbirths occur at term and during labor/delivery. Conditions causing stillbirths include those of maternal origin (obstructed labor, trauma, antepartum hemorrhage, preeclampsia/eclampsia, infection, diabetes, other maternal diseases), and fetal origin (fetal growth restriction, fetal distress, cord prolapse, multiples, malpresentations, congenital anomalies). In LIC, aside from infectious origins, most stillbirths are caused by fetal asphyxia. Stillbirth prevention requires recognition of maternal conditions, and care in a facility where fetal monitoring and expeditious delivery are possible, usually by cesarean section (CS). Of major causes, only syphilis and malaria can be managed prenatally. Targeting single conditions or interventions is unlikely to substantially reduce stillbirth. To reduce stillbirth rates, LIC must implement effective modern antepartum and intrapartum care, including fetal monitoring and CS.