Low-dose calcium supplementation for preventing pre-eclampsia: a systematic review and commentary

Area of Science:

• Obstetrics and Gynecology
• Nutritional Science
• Public Health

Background:

• Epidemiological studies correlate low dietary calcium intake with an increased risk of pre-eclampsia.
• Current recommendations advocate high-dose calcium supplementation (1.5-2 g/day) from 20 weeks gestation, posing logistical challenges and potential risks in resource-limited settings.
• The timing of current recommendations may be too late to effectively alter pre-eclampsia outcomes.

Purpose of the Study:

• To evaluate the impact of lower-dose calcium supplementation on the risk of developing pre-eclampsia.

Main Methods:

• A systematic review was conducted, searching PubMed and the Cochrane Pregnancy and Childbirth Group trials register.
• Data were extracted from eligible randomized and quasi-randomized trials investigating low-dose calcium (LDC, <1 g/day), with or without other supplements.
• Meta-analysis was performed on data from nine trials involving 2234 women.

Main Results:

• Low-dose calcium supplementation, with or without co-supplements, consistently reduced pre-eclampsia risk (relative risk [RR] 0.38; 95% confidence interval [95% CI] 0.28-0.52).
• Subgroup analyses showed significant reductions for LDC alone (RR 0.36; 95% CI 0.23-0.57) and LDC plus linoleic acid (RR 0.23; 95% CI 0.09-0.60).
• A trend towards reduced miscarriage was observed with LDC plus antioxidants initiated early in pregnancy (8-12 weeks).

Conclusions:

• Limited data suggest that low-dose calcium supplementation may effectively reduce the risk of pre-eclampsia.
• Further large-scale, adequately powered randomized controlled trials are needed to confirm these findings.
• Confirmation of these results could lead to significant implications for current global guidelines on calcium supplementation during pregnancy.