The effect of iron supplements on pregnancy in rats given a low-zinc diet

Abstract

1. Female Wistar rats were given an adequate-zinc (60 μg/g) or low-Zn (7 μg/g) diet for a minimum of 2 weeks and then mated. They were then either continued on the same diets (+Zn –Fe or –Zn –Fe) or given similar diets supplemented with four times the normal level of iron (+Zn + Fe or –Zn + Fe). The day before parturition they were killed and the fetuses removed and analysed.2. There were no differences in numbers of fetuses or the number of resorption sites. In the absence of Fe supplementation, the mean fetal wet weight was significantly less (P< 0.05) in the low-Zn group but there was no effect of Zn in the two Fe-supplemented groups. The addition of Fe significantly decreased (P< 0.05) the mean fetal wet weight in the adequate-Zn groups but had no effect in the low-Zn groups. There were no differences in fetal dry weight, fat, protein or DNA content. Both Fe-supplemented groups produced fetuses of higher Fe concentration (P< 0.01), and mothers with higher bone Fe-concentration (P< 0.01) compared with the non-supplemented groups. The low-Zn groups produced fetuses of lower Zn concentration (P< 0,001) than the adequate-Zn groups but there was no effect on maternal bone Zn concentration.3. It was concluded that Fe-supplements did not adversely affect fetal growth from mothers given a low-Zn diet, but the addition of Zn to the unsupplemented diet increased fetal wet weight. These findings were not accompanied by any other differences in fetal composition or dry weight, and do not therefore lend support to the suggestion of an Fe-Zn interaction.