The three specific aims of this study are 1) to assess the impact of iron status on relative differences in absorption of heme and non-heme iron among pregnant women and non-pregnant women, 2) to assess the magnitude and the determinants of heme and non-heme iron transfer to the fetus over the last trimester of pregnancy, and 3) to characterize relationships between placental iron binding proteins with the enrichment of stable iron isotopes in the neonate at birth. The investigators hypothesize that there will be up regulation of heme and non-heme iron absorption and up regulation of placental iron transport proteins in response to low maternal iron stores.

To measure the absorption of heme and non-heme iron in women, pregnant and non-pregnant women will consume a standardized meal of pork (intrinsically labeled with 58Fe) and a second meal of non-heme 57Fe (as ferrous sulfate). Two weeks after ingesting these test meals, a blood sample will be collected from each women and the amount of heme (58Fe) and non-heme (57Fe) iron incorporated into red blood cells will be measured with magnetic sector thermal ionization mass spectrometry. Cord blood samples and placental tissue will be obtained at delivery to measure how these two forms of dietary iron were transferred across the placenta to the fetus. Maternal and neonatal iron status and placental proteins involved in iron transport will also be measured. Data from this study will provide information that aims to improve human health by better understanding the iron requirements of a population at high risk of iron deficiency.

Inclusion Criteria:

• Pregnant subjects (15-35 yrs): non-smoking,healthy with uncomplicated pregnancies at time of enrollment
• Non-pregnant subjects (18-35 yrs): healthy, non-smoking, not taking vitamin or mineral supplements and not planning on becoming pregnant during course of study.

Exclusion Criteria:

• Pregnant subjects: gestational diabetes, hypertension, preeclampsia, underlying malabsorption diseases or other diagnosed medical problems known to impact iron homeostasis
• Non-pregnant subjects: underlying malabsorption diseases or other diagnosed medical problems known to impact iron homeostasis.

Pregnant women and adolescents from Rochester, NY and non-pregnant women from Ithaca, NY.