Study overview
Two independent trials reported in the New England Journal of Medicine in 2024 each enrolled 11,000 nulliparous pregnant women in India and Tanzania. They compared 500 mg with 1500 mg of elemental calcium daily. Preeclampsia results met the noninferiority criterion in both trials; preterm-birth results differed.
- Research focus
- Elemental calcium supplementation, preeclampsia and preterm birth
- Study design
- Two independent parallel-group, double-blind, noninferiority randomized trials
- Study population
- 11,000 nulliparous pregnant women per trial; trials analyzed separately
- Publication / contributor
- New England Journal of Medicine; trial sites in India and Tanzania
Main findings
| Measure | Result | Context |
|---|---|---|
| Participants | 11,000 per trial | Independent trials in India and Tanzania, analyzed separately |
| Comparison | 500 mg vs 1500 mg daily | Elemental calcium; trial regimens |
| Preeclampsia incidence, India | 3.0% vs 3.6% | Lower vs higher dose; noninferiority criterion met |
| Preeclampsia incidence, Tanzania | 3.0% vs 2.7% | Lower vs higher dose; noninferiority criterion met |
| Preterm birth | Noninferiority conclusions differed | Criterion met in India but not in Tanzania |
Results and interpretation
Two randomized trials, conducted separately in India and Tanzania, each enrolled 11,000 nulliparous pregnant women. Daily calcium doses of 500 mg and 1500 mg were compared using a noninferiority design, with preeclampsia and preterm birth as primary outcomes.
The lower dose met the prespecified noninferiority criterion for preeclampsia in both trials. For preterm birth, the criterion was met in India but not in Tanzania, showing different results across endpoints.
Study notes
Participants were adult nulliparous women enrolled early in pregnancy in settings with low dietary calcium intake. The trials were independently designed and analyzed, reflecting their respective populations and conditions.
Noninferiority conclusions depend on prespecified margins and individual endpoints. The differing preterm-birth findings are relevant to the scope of the results.
References
Dwarkanath P, Muhihi A, Sudfeld CR, et al. Two Randomized Trials of Low-Dose Calcium Supplementation in Pregnancy. New England Journal of Medicine. 2024;390(2):143–153. DOI:10.1056/NEJMoa2307212.
