Cochrane Review: Vitamin E supplementation in pregnancy

Wednesday, 29th of June 2016

It is gratifying to see negative results, which are not always published. The issuance of negative results means that scarce resources need not be used on interventions without proven efficacy.

Cochrane Review: Vitamin E supplementation in pregnancy

What is the issue?

Does giving vitamin E supplementation, alone or in combination with other vitamins, given to women during pregnancy improve outcomes for their babies by reducing the incidence of pre-eclampsia and the number of babies born too early? Or does it cause harm?

Why is this important?

Although vitamin E deficiency is rarely seen in healthy adults, for pregnant women, insufficient dietary vitamin E (found in vegetable oils, nuts, cereals and some leafy green vegetables) may lead to complications such as pre-eclampsia and the baby being born small. In addition, vitamin E deficiency can be made worse by too much iron and so it is important to investigate the optimum amounts for pregnancy.

What evidence did we find?

This review included 21 trials involving over 21,000 women. Four trials did not contribute data to the analyses. The trials were generally of variable quality. There were just three studies on vitamin E supplementation alone, but none of these studies contributed data. All other studies included vitamin C, and additional supplements or drugs.

The findings indicate that routine supplementation with vitamin E in combination with other supplements during pregnancy did not improve outcomes for babies or women. There was a reduction in the number of placentas coming away early (placental abruption) in women given vitamin E supplements in combination with other agents, which was rated as high-quality evidence. However, it is unclear whether this finding was due to vitamin E or the other agents used in the supplement. This should be explored in further research examining the mechanisms leading to placental abruption.

The review found there may be harms associated with vitamin E supplements in pregnancy, as there was an increased risk of abdominal pain and term prelabour rupture of fetal membranes in women supplemented with vitamin E in combination with other supplements. There was no increase in preterm prelabour rupture of membranes in women supplemented with vitamin E and other agents.

What does this mean?

The large body of evidence does not support taking vitamin E supplements, alone or in combination, during pregnancy. This is because taking vitamin E in combination with other supplements during pregnancy does not help to prevent problems in pregnancy including stillbirth, baby death, preterm birth, pre-eclampsia or low birthweight babies. In fact, it may increase abdominal pain for women and also increase the number of women having early rupture of membranes at term.

Authors conclusions:

The data do not support routine vitamin E supplementation in combination with other supplements for the prevention of stillbirth, neonatal death, preterm birth, pre-eclampsia, preterm or term PROM or poor fetal growth. Further research is required to elucidate the possible role of vitamin E in the prevention of placental abruption. There was no convincing evidence that vitamin E supplementation in combination with other supplements results in other important benefits or harms.