Women who have first-trimester miscarriages or recurrent miscarriages have been found to have significantly lower selenium status than women who do not miscarry. Professor Margaret Rayman points out that blood selenium concentrations are typically lower during pregnancy, in part because there is an expansion of the volume of blood. However, increased inflammation – implicated in miscarriages – could also be a cause of reduced circulating selenium [Rayman 2012].
For this article, I have searched the Medline database for results from randomized controlled studies involving selenium supplementation of low selenium status pregnant women. There have been a number of interesting results.
Selenium and oxidative stress in pregnant women
Dr. Tara and a team of researchers did a simultaneous assay of pro-oxidant burden and antioxidant capacity in a total of 166 first-time-pregnant women. In their first trimester, the women were randomly assigned to an active treatment group receiving 100 micrograms of a yeast-based selenium preparation (n=83) or placebo (n=83) per day until delivery.
The study results showed that selenium supplementation may reduce oxidative stress associated with pregnancy. Oxidative stress is the bio-medical term for the damage that is done to cells by harmful free radicals if the free radicals are not neutralized by antioxidants such as various selenium containing selenoproteins, Coenzyme Q10, vitamins C and E, and so on [Tara].
Selenium and thyroid function in pregnant women
Dr. Negro and a team of researchers investigated the protective effect of supplementation of pregnant women with 200 micrograms of selenium daily during the course of the women’s pregnancies.
The research findings indicated that selenium supplementation during pregnancy and in the postpartum period reduced thyroid inflammatory activity and the incidence of hypothyroidism [Negro].
Selenium and high blood pressure in pregnant women
Dr. Han and Dr. Zhou studied the effect of supplementation with 100 micrograms of selenium daily for 6-8 weeks during late pregnancy. The women in the selenium treatment group and in the placebo group received similar prenatal care. The study results showed that the selenium supplement of the pregnant women prevented and decreased the incidence of pregnancy-induced hypertension and gestational edema [Han].
Selenium and pre-eclampsia in pregnant women
Pre-eclampsia is a serious complication of pregnancy characterized by high blood pressure midway through the pregnancy in women whose blood pressure has been normal. Left untreated, pre-eclampsia can result in serious consequences for the mother and fetus.
Dr. Rayman and a team of researchers tested whether supplementation with 60 micrograms daily of an organic high-selenium yeast preparation would protect pregnant women against pre-eclampsia. Starting in week 12 – 14 of the pregnancy, the women in the study received the active selenium tablet or a placebo tablet. The supplementation continued until delivery of the baby.
In week 35, the researchers measured the study participants’ serum concentrations of sFlt-1. The sFlt-1 molecules are vascular endothelial growth factor receptor-1 proteins that are good predictors of the risk of pre-eclampsia. The concentrations of sFlt-1 were significantly lower in the selenium treatment group than in the placebo group among the pregnant women with the lowest selenium status at baseline.
The researchers concluded that selenium supplementation may reduce the risk of pre-eclampsia in women with low selenium status [Rayman 2014].
Selenium and pre-labor rupture of membranes in pregnant women
Dr. Tara and a team of researchers reported that 166 women, who were pregnant for the first time and who were in the first trimester, were randomly assigned to receive 100 micrograms per day of a patented organic high-selenium yeast preparation or a matching placebo tablet.
The study data showed that the incidence of Premature (pre-labor) Ruptures of Membranes was significantly lower in the selenium group than in the placebo control group [Tara].
Selenium and postpartum depression in new mothers
Dr. Mokhber and a team of researchers assigned 44 first-time-pregnant women to a selenium supplementation group and 41 first-time-pregnant women to a placebo group. After the women had given birth, the researchers administered the Edinburgh Postnatal Depression Scale (EPDS) questionnaire to the study participants.
The women in the selenium treatment group had EPDS depression scores significantly lower than the EPDS score of the women in the placebo control group. The researchers concluded that supplementation with an organic high-selenium yeast supplement during pregnancy might reduce the risk of postpartum depression.
Safety of selenium supplementation in pregnancy
Supplementation of 83 first-time-pregnancy women with an organic high-selenium yeast preparation from the first trimester until delivery in the studies conducted by Dr. Tara and her team increased mean serum selenium levels by the end of the pregnancy. The pregnant women receiving the active selenium supplement did not report any major side effects [Tara].
Summary: Selenium supplements and pregnant women
Both selenium status and selenium intake seem to play an important role in reducing the risk of pregnancy complications:
- risk of excessive oxidative stress and/or inflammation
- risk of of miscarriage or pre-term birth
- risk of of pre-eclampsia and pregnancy-induced high blood pressure
- risk of post-partum depression.
Han, L., & Zhou, S. M. (1994). Selenium supplement in the prevention of pregnancy induced hypertension. Chinese Medical Journal, 107(11), 870-871.
Mokhber, N., Namjoo, M., Tara, F., Boskabadi, H., Rayman, M. P., Ghayour-Mobarhan, M., & Ferns, G. (2011). Effect of supplementation with selenium on postpartum depression: a randomized double-blind placebo-controlled trial. The Journal of Maternal-Fetal & Neonatal Medicine, 24(1), 104-108.
Negro, R., Greco, G., Mangieri, T., Pezzarossa, A., Dazzi, D., & Hassan, H. (2007). The influence of selenium supplementation on postpartum thyroid status in pregnant women with thyroid peroxidase autoantibodies. The Journal of Clinical Endocrinology and Metabolism, 92(4), 1263-1268.
Rayman, M.P., Searle, E., Kelly, L., Johnsen, S. (2014). Effect of selenium on markers of risk of pre-eclampsia in UK pregnant women: a randomised, controlled pilot trial. British Journal of Nutrition, 112(1), 99-111.
Tara, F., Rayman, M. P., Boskabadi, H., Ghayour-Mobarhan, M., Sahebkar, A., Alamdari, D. H., & Ferns, G. (2010). Prooxidant-antioxidant balance in pregnancy: a randomized double-blind placebo-controlled trial of selenium supplementation. Journal of Perinatal Medicine, 38(5), 473-478.
Tara, F., Rayman, M. P., Boskabadi, H., Ghayour-Mobarhan, M., Sahebkar, A., Yazarlu, O., & Ferns, G. (2010). Selenium supplementation and premature (pre-labour) rupture of membranes: a randomised double-blind placebo-controlled trial. Journal of Obstetrics and Gynaecology, 30(1), 30-34.
Tara, F., Maamouri, G., Rayman, M. P., Ghayour-Mobarhan, M., Sahebkar, A., Yazarlu, O., & Ferns, G. (2010). Selenium supplementation and the incidence of preeclampsia in pregnant Iranian women: a randomized, double-blind, placebo-controlled pilot trial. Taiwanese Journal of Obstetrics & Gynecology, 49(2), 181-187.
Disclaimer: The information presented in this review article is not intended as medical advice and should not be construed as such.