Hofmeyr GJ, et al. - In this multicountry, parallel arm, double-blind, randomised, placebo-controlled trial, researchers tested the premise that pre-eclampsia development is prevented by calcium supplementation before and during early pregnancy (up to 20 weeks' gestation). Compared with placebo, calcium supplementation that began before pregnancy until 20 weeks of gestation did not show a significant reduction in recurrent pre-eclampsia. No serious adverse effects of calcium were identified in this trial.

Methods

• This trial was conducted in South Africa, Zimbabwe, and Argentina.
• For this investigation, participants with previous pre-eclampsia and eclampsia received 500 mg of calcium or placebo daily from prepregnancy until 20 weeks' gestation.
• Parous women whose latest pregnancy was complicated by pre-eclampsia or eclampsia and who intended to become pregnant were participants.
• After 20 weeks' gestation, all participants received unblinded calcium 1·5 g daily.
• The allocation sequence (1:1 ratio) used random numbers generated by the computer in balanced blocks of variable size.
• Pre-eclampsia [defined as gestational hypertension and proteinuria] was the primary outcome.

Results

• Between July 12, 2011, and September 8, 2016, 1355 women were allocated randomly to receive calcium or placebo; 331 out of 678 participants in the calcium group were pregnant vs 320 out of 677 in the placebo group, and 298 out of 678 out of 283 out of 677 were pregnant beyond 20 weeks' gestation.
• Investigators found that pre-eclampsia occurred in 69 (23%) of 296 calcium group participants vs 82 (29%) of 283 placebo group participants with pregnancies beyond 20 weeks' gestation (risk ratio [RR] 0·80, 95% CI 0·61–1·06; p=0·121).
• The pre-eclampsia risk was 30 (21%) of 144 vs 47 (32%) of 149 (RR 0·66, CI 0·44–0·98; p=0·037) for participants with compliance of more than 80% from the last visit before pregnancy to 20 weeks' gestation.
• No serious adverse effects of calcium were identified.