Obesity and overweight during pregnancy reduces cord blood hepcidin

Iron availability during pregnancy and in the infant after birth are critical for neurocognitive and socioemotional development of the child.  Iron availability is regulated by hepcidin, a hormone that becomes elevated by inflammation and by high iron stores, leading to reduced iron absorption.  The inflammation caused by obesity and overweight may explain recent observations that hepcidin is elevated in women of child-bearing age affected by obesity. Other observations have noted that women with obesity tend to have children with lower neonatal iron status. This becomes a major issue in areas of the world where obesity rates are increasing and iron deficiency is prevalent.  It is unclear if the impact of overweight and obesity on iron status of the neonate is controlled by hepcidin.  Jones and colleagues conducted a study to address this void in our understanding of iron regulation during pregnancy, and they report their results in the August 2021 issue of The Journal of Nutrition.

Data for this study included hematological results acquired from 405 pregnant women and infants in China.  Hepcidin, serum ferritin, soluble transferrin receptor, and C-reactive protein were measured at mid-pregnancy and in cord blood.  These data were used to explore the relationship between overweight/obesity and hepcidin levels in the mother and neonate, as well as maternal and neonatal iron status.

Weight status did not influence maternal hepcidin levels at mid-pregnancy, but hepcidin levels were positively related to maternal iron status at that time.  Hepcidin levels in cord blood was positively correlated with iron status of the neonate.  Mild pre-pregnancy obesity or overweight status led to lower cord blood hepcidin levels.  These observations led the authors to conclude hepcidin is responsive to iron status, and that being affected by obesity before pregnancy is associated with lower cord blood hepcidin, which can lower iron status of the neonates from those mothers.

In a commentary, Frazer and Anderson discuss the apparent lack of influence of maternal BMI on the ability of the placenta to transfer iron from the maternal circulation to the fetus, but they noted that the supply of iron to the placenta may be affected. Lower availability of iron to the fetus as a result can contribute to iron deficiency anemia by 6 months of age, which has been reported.  Frazer and Anderson suggest screening programs targeted to neonates born from women with obesity or overweight may be needed in order to avoid further increases in iron deficiency and its detrimental effects.

References

Andrew D Jones, Zhen Shi, Nathalie J Lambrecht, Yaping Jiang, Jingmin Wang, Margit Burmeister, Ming Li, Betsy Lozoff, Maternal Overweight and Obesity during Pregnancy Are Associated with Neonatal, but Not Maternal, Hepcidin Concentrations, The Journal of Nutrition, Volume 151, Issue 8, August 2021, Pages 2296–2304, https://doi.org/10.1093/jn/nxab133.

David M Frazer, Gregory J Anderson, Ironing Out the Effects of Overweight and Obesity on Hepcidin Production during Pregnancy, The Journal of Nutrition, Volume 151, Issue 8, August 2021, Pages 2087–2088, https://doi.org/10.1093/jn/nxab200.

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