The mechanisms that explain these adverse effects
due to excessive iron intake have not yet been clearly
established; however, several potential mechanisms have
been suggested. Primarily, excessive iron intake could
cause free-radical damage during pregnancy [30-32].
Pregnancy itself is vulnerable to oxidative stress [31].
Free iron catalyzes the transformation of hydrogen peroxide
to a hydroxyl radical via the Fenton Reaction. Studies
have shown that the levels of free radicals were higher in
pregnant women who consumed iron supplements in
Estonia (36 mg/d) [33] and in the US (19 mg/d) [34] than
those without any consumption of supplements. The free
radicals have been reported to damage cellular DNA, proteins
and lipids [35]. According to Takagi et al., the level
of oxidative stress and redox-related molecules was higher
in the placenta in preeclampsia and IUGR than in normal
pregnancy [36]. Secondly, previous studies have reported
that iron supplements could interrupt the absorption of
zinc and copper in pregnant women with Hb ≥132 g/L
[37,38] or with normal Hb levels [39,40]; the reason being
competitive absorption of iron, zinc, and copper from the
small intestine via divalent metal transporter