Research evidence shows that calcium helps prevent preeclampsia and preterm birth, and reduces the risks and complications for women that can arise from high blood pressure during pregnancy. This is especially important for women who do not consume enough calcium daily.
- preeclampsia: a pregnancy complication characterized by high blood pressure and protein in the urine. It is associated with high infant and maternal mortality rates worldwide
- preterm birth: birth before the completed 37th week of pregnancy
A review of 24 trials showed high-quality evidence that calcium doses of at least 1 g per day during pregnancy (13 studies involving 15,730 women) are a safe and relatively inexpensive way to reduce the risk of preeclampsia, especially in women who do not eat calcium-rich foods. No harmful effects were found, though further research is needed on the ideal daily dose of calcium. Limited evidence from 10 trials (2,234 women) suggests that a relatively low dose can be effective, although 6 trials included other supplements such as vitamin D, linoleic acid, and antioxidants.
Calcium supplementation (≥ 1 g/day) is associated with a significantly lower risk of developing preeclampsia, especially in women who do not eat calcium-rich foods. It also reduces the chance of preterm birth and other serious complications that can be linked to maternal mortality. These benefits outweigh the increased possibility of developing HELLP syndrome. The World Health Organization recommends 1.5–2 g of calcium per day for pregnant women with low dietary calcium intake.
