Maternal selenium intake and selenium status during pregnancy in relation to preeclampsia and pregnancy-induced hypertension in a large Norwegian Pregnancy Cohort Study

Background: Pregnancy-induced hypertensive disorders (PIHD), including preeclampsia, cause maternal and perinatal morbidity and mortality worldwide. Several studies have linked selenium supplementation and selenium status to the risk of preeclampsia, but there are no published prospective population-based studies examining associations between dietary selenium intake and preeclampsia.

Aim: To examine associations between selenium intake from diet and supplements and selenium blood status and PIHD incidence, with sub-analyses for pregnancy-induced hypertension (PIH) and preeclampsia, in a large pregnancy cohort.

Method: The study is based on 69,972 singleton pregnancies from the Norwegian Mother, Father and Child Cohort Study. Maternal dietary selenium intake was assessed with a validated, semi-quantitative food frequency questionnaire at about gestational week 22. Maternal selenium concentrations were measured in whole blood collected around gestational week 18 in a subset of 2572 women. Preeclampsia and PIH diagnosges were obtained from the Medical Birth Registry of Norway.

Results: Participants had a median dietary selenium intake of 53 μg/day (IQR 44-62). Dietary selenium intake was not significantly associated with PIHD (adjusted (a) OR 1.03, 95% CI 0.98, 1.08 per SD of selenium intake), preeclampsia or PIH. Threshold analyses for deciles of dietary selenium intake did not show any significant associations. Neither inorganic (aOR 1.01, 95% CI 0.98, 1.05) or organic selenium supplement intake (aOR 0.98, 95% CI 0.95, 1.02) or selenium blood status was significantly associated with PIHD (aOR 1.03, 95% CI 0.86, 1.22) or PIHD subgroups.

Conclusion: No significant associations were found between reported selenium intake from diet, or dietary supplements or whole-blood selenium status and PIHD in general or preeclampsia specifically. Hence, the results of this large population-based study, with selenium intake close to the recommended daily intake, do not support previous findings indicating a possible protective effect of selenium supplementation or selenium status with regard to preeclampsia incidence.