Iron Absorption and Transfer to the Fetus During Pregnancy in Normal Weight and Overweight/Obese Women and the Effects on Infants Iron Status

In obese subjects, hepcidin concentrations are increased and iron absorption is believed to be reduced, leading to iron deficiency over time. How all this will influence iron supply of the fetus in obese pregnancy has not been well investigated to date. Even if maternal and fetal iron uptakes are regulated separately, it is unclear to what extent maternal subclinical inflammation might influence this process. A small study by Dao et al. indicated that maternal-fetal iron transfer was impaired in obese pregnant women, possibly due to hepcidin up-regulation. In this study, both maternal BMI as well as hepcidin were negatively correlated with cord blood iron status. Maternal hepcidin and c-reactive protein were significantly higher and cord blood iron was significantly lower in the obese compared to the normal weight. Hepcidin was shown to have an effect on iron transfer across the placenta in the study by Young et al.: the transfer was increased in women with undetectable hepcidin at delivery compared to those with higher levels. As of now, clear associations between maternal BMI or maternal hepcidin concentration and fetal iron status were not shown.

Inclusion criteria

• Pregnant women with either normal pre-pregnancy BMI (BMI 18.5 - 24.9kg/kg2) or with overweight or obesity (BMI > 27.5kg/m2) before pregnancy (assessed based on data reported by the women at their first visit at the hospital)
• 18 to 45 years old
• singleton pregnancy
• week of pregnancy 14±3

Exclusion criteria

• underlying malabsorption disease
• chronic illness, which influences iron absorption
• inflammatory status other than obesity
• medical problems known to affect iron homeostasis
• smoking during pregnancy
• no regular use of medication, which influences iron absorption