Calcium supplementation for the prevention of hypertensive disorders of pregnancy: current evidence and programmatic considerations

Abstract

Most low-and middle-income countries present suboptimal intakes of calcium during pregnancy and high rates of mortality due to maternal hypertensive disorders. Calcium supplementation during pregnancy is known to reduce the risk of these disorders and associated complications, including preeclampsia, maternal morbidity, and preterm birth, and is, therefore, a recommended intervention for pregnant women in populations with low dietary calcium intake (e.g., where ≥25% of individuals in the population have intakes less than 800 mg calcium/day). However, this intervention is not widely implemented in part due to cost and logistical issues related to the large dose and burdensome dosing schedule (three to four 500-mg doses/day). WHO recommends 1.5-2 g/day but limited evidence suggests that less than 1 g/day may be sufficient and ongoing trials with low-dose calcium supplementation (500 mg/day) may point a path toward simplifying supplementation regimens. Calcium carbonate is likely to be the most cost-effective choice, and it is not necessary to counsel women to take calcium supplements separately from iron-containing supplements. In populations at highest risk for preeclampsia, a combination of calcium supplementation and food-based approaches, such as food fortification with calcium, may be required to improve calcium intakes before pregnancy and in early gestation.

Calcium deficiency worldwide: prevalence of inadequate intakes and associated health outcomes

“…Conversely, EFSA did not establish a calcium upper limit for infants, children, and adolescents due to insufficient information for these age groups. Adverse effects of calcium supplementation have also been systematically investigated and are covered in greater detail elsewhere in this special issue 8 …”

“…One of the most well‐documented benefits of calcium supplementation beyond bone health is a significant reduction in the risk of preeclampsia and maternal morbidity in pregnant women and preterm birth. This topic is, therefore, discussed in detail elsewhere in this special issue 8 …”

Interventions to improve calcium intake through foods in populations with low intake

“…Some studies have also cited the interactions between calcium and zinc absorption, but longer‐term studies are needed to determine if this effect is limited to the short‐term, as it is for iron 110 . For more information on this, see the paper on supplementation in this special issue 86 …”

“…A recent systematic review suggests the short‐term effect is small, but more work is needed to better understand the effect 154 . This is described in more detail in the supplementation article in this special issue 86 . With respect to foods, the quantities of micronutrients consumed at any one time are likely to be smaller and thus have a less of an impact on absorption.…”

“…110 For more information on this, see the paper on supplementation in this special issue. 86 When fortifying foods, it is important to consider the percent of the population at risk of reaching or exceeding the UL with the fortified foods. However, for calcium, the amount that would typically be added to a fortified food would be relatively low due to calcium's effect on organoleptic properties and acceptability when compared with the relatively high UL (2500 mg/day for most adults).…”