Observational studies have found that maternal calcium supplementation reduces the onset and progression of hyperemesis. Clinical trials have also confirmed that calcium supplementation reduces hypertension and blood pressure-related disorders during pregnancy. A systematic analysis of relevant clinical trials registered with the World Health Organization (WHO) and a review of the WHO Reproductive Health Library (RHL) suggest that the intervention of calcium supplementation (≥1.0 g/day) before 34 weeks of gestation in pregnant women without hypertension may have an impact on the prevention of hypertension and other pregnancy outcomes (such as maternal proteinuria, preterm delivery, stillbirth and neonatal admission to the intensive care unit The impact of this intervention on the prevention of hypertension and other pregnancy outcomes (such as maternal proteinuria, preterm delivery, stillbirth and neonatal intensive care unit admission, neonatal death) was objectively assessed. A total of 12 randomized controlled trials with 15,528 pregnant women were included in the systematic analysis. The results showed that: (1) women who took calcium supplementation (>1.0 g/day) during pregnancy had a significantly reduced risk of hypertension (with or without proteinuria) compared with those who took placebo; the risk reduction was more pronounced in women with a higher risk of preeclampsia and a lower dietary calcium intake; (2) similarly, women who took calcium supplementation (>1.0 g/day) during pregnancy were only 50% as likely to have preeclampsia as those who took placebo; The risk reduction was more pronounced in women with a higher risk of preeclampsia and a lower dietary calcium intake; (3) analysis of data from four trials (9,732 pregnant women) suggested that women who took calcium supplementation (>1.0 g/day) during pregnancy had a significantly lower risk of maternal death or serious illness compared with those who took placebo. However; ④ The differences between pregnant women who supplemented with calcium (>1.0 g/day) and those who took placebo were not statistically significant for the following pregnancy outcomes: early placental abruption, cesarean delivery, proteinuria, eclampsia, maternal need for a supervised unit, maternal death, maternal hospital stay ≥7 days, preterm delivery, stillbirth, low birth weight, neonatal need for a supervised unit, neonatal hospital stay ≥7 days, and death before hospital discharge. Based on these results, the authors concluded that calcium supplementation may reduce the risk of pregnancy-induced hypertension and preeclampsia. Furthermore, the authors make three recommendations on how to supplement calcium: (1) in a comparison of several calcium preparations, calcium fructate is more bioavailable, can be taken on an empty stomach, and is adequately absorbed; and (2) the current multivitamins and minerals used during pregnancy contain much lower concentrations of calcium than are needed to reduce the risk of hypertensive disorders. Therefore, calcium supplementation should not be neglected because of the multivitamins taken for pregnant women; (3) attention should be paid to the interaction between calcium and other important trace elements required during pregnancy (iron, zinc, magnesium and phosphorus). Calcium has an inhibitory effect on iron absorption, and daily calcium supplementation should be separated in time from iron supplementation and oral folic acid. Also, the authors raise two questions: (1) Does the timing of starting calcium supplementation need to be appropriately advanced? The available analyses are based on clinical data on calcium supplementation before 34 weeks of gestation (mostly at 20-27 weeks), but some studies suggest the need to start calcium supplementation in the periconceptional period or at least in early pregnancy; (2) Are there any long-term effects of maternal hypertensive status during pregnancy or calcium supplementation on the fetus? Is it necessary to follow the blood pressure of children in these studies? These questions need to be addressed in future studies.