Global inequities in dietary calcium intake during pregnancy: a systematic review and meta‐analysis

BACKGROUND: Evidence shows that adequate calcium intake during pregnancy reduces the risk of hypertensive disorders of pregnancy. In most low‐ and middle‐income countries (LMICs) the daily calcium intake is well below recommendations. Mapping calcium intake during pregnancy worldwide and identifying populations with low calcium intake will provide the evidence base for more targeted actions to improve calcium intake. OBJECTIVE: To assess dietary calcium intake during pregnancy worldwide. SEARCH STRATEGY: MEDLINE and EMBASE (from July 2004 to November 2017). SELECTION CRITERIA: Cross‐sectional, cohort, and intervention studies reporting calcium intake during pregnancy. DATA COLLECTION AND ANALYSIS: Five reviewers working in pairs independently performed screening, extraction, and quality assessment. We reported summary measures of calcium intake and calculated the weighted arithmetic mean for high‐income countries (HICs) and LMICs independently, and for geographic regions, among studies reporting country of recruitment, mean intake, and total number of participants. When available, inadequate intakes were reported. MAIN RESULTS: From 1880 citations 105 works met the inclusion criteria, providing data for 73 958 women in 37 countries. The mean calcium intake was 948.3 mg/day (95% CI 872.1–1024.4 mg/day) for HICs and 647.6 mg/day (95% CI 568.7–726.5 mg/day) for LMICs. Calcium intakes below 800 mg/day were reported in five (29%) countries from HICs and in 14 (82%) countries from LMICs. CONCLUSION: These results are consistent with a lack of improvement in calcium dietary intake during pregnancy and confirm the gap between HICs and LMICs, with alarmingly low intakes recorded for pregnant women in LMICs. From the public health perspective, in the absence of specific local data, calcium supplementation of pregnant women in these countries should be universal. TWEETABLE ABSTRACT: Despite dietary recommendations, women in LMICs face pregnancy with diets low in calcium.