Getting a Goldilocks Dose of Iron

Iron supplements in pregnancy taken two or three times a week generally sufficient

/ Author:  / Reviewed by: Joseph V. Madia, MD

(RxWiki News) Pregnant women need sufficient amounts of iron, which is included in most prenatal vitamins. But like many supplements, taking too much iron can have negative side effects.

A recent review of the research literature has found that taking iron a couple of times a week is just as good as taking iron daily - and has fewer side effects.

"Ask your OB/GYN what pregnancy supplements you should take."

In a review of the research led by Juan Pablo Peña-Rosas, MD, PhD, of the Department of Nutrition for Health and Development at the World Health Organization in Geneva, researchers looked at 18 clinical trials that involved a total of 4,072 pregnant women.

The women in the trials took iron supplements alone, combined supplements with iron and folic acid, or multivitamins that included iron.

Iron deficiency can lead pregnant women to experience anemia (a condition where the red blood cells do not carry enough oxygen) which can cause birth complications.

Babies can also suffer if their pregnant mothers do not get sufficient iron: they may be born underweight or experience slower growth and development later in life. Too much iron can lead to similar problems, including early birth.

The research data revealed that women who took supplements once, twice or three times spread throughout each week did not become anemic at rates any higher than the women who took iron supplements daily.

Neither group saw an increased number of early births or babies with low birth weights either.

Yet the women taking the daily supplements were more likely to experience a handful of side effects from the iron, including nausea, constipation and higher levels of hemoglobin (the substance in red blood cells that carries oxygen).

"Intermittent iron supplementation could be considered as a feasible alternative to daily supplementation for preventing anaemia during pregnancy," Dr. Peña-Rosas said. "At the moment evidence is limited and the quality of the trials included in our review was generally low."

The authors did call for further research on the topic to get a better sense of how much iron pregnant women need and the best way to ensure they get that amount without getting too much.

The study was published June 10 in the Cochrane Database of Systematic Reviews. The research was funded by the Children's Hospital and Oakland Research Institute in the US, the University of Liverpool in the United Kingdom and the Department of Nutrition for Health and Development at WHO.

Other than having authored or working on other studies related to iron supplementation in pregnancy, the authors declared no conflicts of interest.

Reviewed by: 
Review Date: 
July 12, 2012
Last Updated:
December 30, 2012