Maternal iron kinetics and maternal–fetal iron transfer in normal-weight and overweight pregnancy

Abstract

Background Inflammation during pregnancy may aggravate iron deficiency by increasing serum hepcidin and reducing iron absorption. This could restrict iron transfer to the fetus, increasing risk for infant iron deficiency and its adverse effects. Objectives To assess whether iron bioavailability and/or iron transfer to the fetus is impaired in overweight/obese (OW) women with adiposity-related inflammation, compared to normal weight (NW), pregnant women. Design In this prospective study, we followed NW (n = 43) and OW (n = 40) pregnant women who were receiving iron supplements from the 14th gestational week to term and followed their infants to age six months. We administered 57Fe and 58Fe in test meals mid-2nd and mid-3rd trimester, and measured tracer kinetics throughout pregnancy and infancy. Results 38 NW and 36 OW completed the study to pregnancy week 36 and 30 NW and 27 OW mother infant pairs completed the study to six months postpartum. Both groups had comparable iron status, hemoglobin and serum hepcidin throughout pregnancy. Compared to the NW, the OW pregnant women had: 1) 43% lower fractional iron absorption in the 3rd trimester (P = 0.033) with median (IQR) 23.9 (11.4–35.7) and 13.5 (10.8–19.5) %; and 2) 17% lower maternal-fetal iron transfer from the first tracer (P = 0.051) with median (IQR) 4.8 (4.2–5.4) and 4.0 (3.6–4.6) %. Compared to the infants born to NW, infants born to OW had lower body iron stores (BIS) with median (IQR) 7.7 (6.3–8.8) and 6.6 (4.6–9.2) mg/kg body weight at age six months (P = 0.024). Prepregnancy BMI was a negative predictors of maternal-fetal iron transfer (β = –0.339, SE = 0.144, P = 0.025) and infant BIS (β = –0.237, SE = 0.026, P = 0.001). Conclusions Compared to NW, OW pregnant women fail to upregulate iron absorption in late pregnancy, transfer less iron to their fetus, and their infants have lower BIS. These impairments are associated with inflammation independent of serum hepcidin. The study was registered at clinicaltrials.gov (NCT02747316).

Nutrition in chronic inflammatory conditions: Bypassing the mucosal block for micronutrients

“…Naïve T cell diseases due to decreased uptake 335,336 and does not improve the iron status in obese patients. 46,337 In the presence of low-grade inflammation, clinical trials have shown that the addition of vitamin A, 338 vitamin C, 140,310 antioxidants improve dietary iron uptake. Low-hemoglobin levels in pregnant women were also negatively correlated with the breast milk iron content.…”

“…Though calcium can impede iron absorption, this only seemed to be true to a modest degree of about 20%, when excessive high amount of calcium was consumed 330–334 . Iron absorption is impeded upon immune activation due to hepcidin, and thus oral iron may even enhance disease activity in inflammatory bowel diseases due to decreased uptake 335,336 and does not improve the iron status in obese patients 46,337 …”

Trends in the Intraindividual Double Burden of Overweight/Obesity and Anemia among Adult Women Living in 33 Low- and Middle-Income Countries: A Secondary Analysis of Demographic and Health Surveys from 2000-2019

“…Maternal pregestational overweight/obesity has been hypothesized to increase the risk of childhood anemia [ [53] , [54] , [55] ]. A recent prospective study that followed up pregnant women and their infants to 6 mo of age from 3 different countries (Switzerland, Mexico, and Thailand) found that, when compared to pregnant women with normal weight, those with overweight/obesity showed impaired iron absorption in late pregnancy, transferred less iron to their fetuses, and their infants had lower body iron stores [ 56 ]. Likewise, maternal obesity increases the risk of fetal macrosomia, which in turn, may lead to inflammation, a rise in hepcidin levels, and over time, result in anemia of inflammation [ 55 , 57 ].…”

Iron Status in Pregnant Women in Latvia: An Epidemiological, Cross-Sectional, Multicenter Study According to WHO and UK Criteria

“…Iron status depends not only on total iron intake but also on the absorption and availability of iron in the body [ 23 , 37 ]. Haem iron is absorbed more easily from the main sources, which are meat and fish [ 38 ].…”