Effect of selenium on markers of risk of pre-eclampsia in UK pregnant women: a randomised, controlled pilot trial

Randomized, double-blind, placebo-controlled pilot trial in primiparous pregnant women in Oxford, United Kingdom, recruited at about 12.3 weeks' gestation and followed until delivery. Women had inadequate selenium status at baseline; one participant was recruited at 16 weeks and included in the analysis.

Participants received oral selenium as Se-enriched yeast (SelenoPrecise) 60 mg/d daily from randomization at 12 to 14 weeks of gestation until delivery. The active intervention was compared with placebo in a 1:1 randomized, double-blind design.

Selenium supplementation improved selenium status and showed a signal of benefit in the subgroup with the lowest baseline selenium. In that bottom quartile, selenium lowered sFlt-1 at 35 weeks versus placebo (5.22 ng/ml vs 7.49 ng/ml; ratio 0.70, 95% CI 0.49, 0.98; P 0.039), while across all participants there was no significant effect on sFlt-1 (ratio 0.95, 95% CI 0.80, 1.12; P 0.511). SEPP1 was higher with selenium than placebo at 35 weeks (5.30 mg/ml vs 3.00 mg/ml; P 0.0001), and whole-blood selenium increased in the selenium group but fell in placebo (baseline 1.31 mmol/l to 1.87 mmol/l vs 1.32 mmol/l to 1.16 mmol/l; P 0.0001 for comparison). Pre-eclampsia or pregnancy-induced hypertension occurred in 11 cases overall, and the combined PE/PIH outcome favored selenium (OR 0.350, 95% CI 0.126, 0.974; P 0.044), but most secondary biomarkers were unchanged and the pilot trial was underpowered for definitive clinical conclusions.

This was a small pilot trial and the authors note it was underpowered to detect definitive clinical effects. The primary biomarker was not improved in the overall cohort, benefits were mainly seen in the lowest baseline selenium subgroup, and most secondary outcomes were null. Generalizability is limited to primiparous pregnant women in one UK center, with one late recruit and limited detail on baseline dietary and supplementation status.