Background: The purpose of this study was compare of daily iron supplementation in three time frames- daily, weekly and three time weekly supplementation in preventing anemia in healthy pregnant women.

Method: The present study was a prospective simply randomized clinical trial. During January 2006- January 2008, 150 healthy pregnant women without anemia, in their 16th week of pregnancy were randomly allocated into three equal groups. The first group (n = 50) received a 50 mg-ferrous sulfate tablet daily, second group (n = 50) received a 50 mg-ferrous sulfate tablet three times a week, and the third group (n = 50) received two 50 mg-ferrous sulfate tablets (100 mg) weekly, respectively for 12 consecutive weeks. Serum hemoglobin, ferritin, and iron were measured before and after the supplementation. Paired t and ANOVA tests were used as appropriated.

Results: There were no significant differences between the pre- and post-treatment hemoglobin levels with iron supplementation in the three group (P = 0.518, P = 0.276, respectively). The mean serum iron level before and after treatment with iron supplementation in the three groups was not statistically significant (P = 0.962, P = 0.970, respectively). Although the mean serum ferritin level before and after treatment with iron supplementation was statistically significant in the three groups, no significant differences were found comparing the three groups (P = 0.827, P = 0.635 respectively).

Conclusions: This results suggested, three times a week or weekly iron supplementation is as effective as daily supplementation for healthy pregnant women without anemia.

Trial registration: ISRCTN: IRCT201101093820N1.