• Assessment of the risk of developing gestational hypertensive disorders is to be conducted by a clinician. The clinical management of women with pre-eclampsia or eclampsia requires consideration of other evidence-informed interventions (5).
  • Implementation of this recommendation requires close monitoring of women's total daily calcium intake (diet, supplements and antacids). The overall intake of calcium per day should not exceed the locally established upper tolerable limit. In the absence of such reference standards, an upper limit of calcium intake of 3 g/day can be used (7).
  • The mechanisms through which calcium reduces the risk of gestational hypertension need further elucidation. Available evidence supports the theory that calcium supplementation may reduce the risk of developing pre-eclampsia by filling a dietary gap in calcium intake (5). In populations where consumption of calcium on average meets the recommended dietary calcium intake, either through calcium-rich foods or fortified staple foods, calcium supplementation is not encouraged as it may not improve the outcomes related to pre-eclampsia and hypertensive disorders of pregnancy but might increase the risk of adverse effects. Although antacids are not a rich source of calcium, they are not part of the diet and their use should be limited to the treatment of heartburn or indigestion. The calcium content of any other vitamin and mineral supplements that are also being taken should be considered when recommending calcium supplementation, to reduce the risk of hypercalcaemia.
  • Determination of the dietary calcium intake of an individual woman is a complex task. The target group for this recommendation comprises populations with observed low dietary calcium intake or those living in geographical areas where calcium-rich foods are not commonly available or consumed (5). Calcium intake at population level can be estimated through various means including dietary surveys using 24-hour recalls, food frequency questionnaires or food weighing, as well as through secondary data estimates derived from FAO food balance sheets or household consumption and expenditure surveys (20, 21).
  • Healthy dietary practices to promote adequate calcium intake through local calcium-rich foods should be encouraged in the general population, including pregnant women (5).
  • Interaction between iron supplements and calcium supplements may occur, although the consequences of prolonged calcium supplementation for iron status among different age groups are still unclear (2225). Therefore, the two nutrients should preferably be administered several hours apart (i.e. iron may be consumed between meals) rather than concomitantly.
  • Selection of the most appropriate delivery platform should be context-specific, with the aim of reaching the most vulnerable populations and ensuring a timely and continuous supply of supplements. Calcium supplementation could be delivered by lay health workers along with targeted monitoring and evaluation (26).
  • Calcium supplements are available as tablets or capsules. Tablets (soluble tablets, effervescent tablets, chewable tablets for use in the mouth and modified-release tablets) are solid dosage forms containing one or more active ingredients (27).