Iron Absorption and Requirements in Pregnancy and Lactation

Official title

Assessment of Iron Absorption and Requirements During Pregnancy and Lactation in Kenyan Women

Overview

Iron requirements increase significantly during pregnancy. Current recommendations for iron intake in pregnant and lactating women (PLW) are mainly based on factorial estimates and extrapolated from non-PLW. High-quality quantitative data on iron requirements in PLW are lacking, particularly in Sub- Saharan Africa where anaemia and infections are common. The primary objective of this study is to use the stable iron isotope technique to determine iron requirements and assess iron absorption and losses in PLW living in Kenya. In this prospective observational study, we will enrol pregnant women in the first trimester (n = 250) from a previous study cohort (n=1000) who participated in an iron absorption study at least 12 months ago and received the stable iron (Fe) isotope 57Fe. This 57Fe has now distributed and equilibrated throughout the women's body iron. Once enrolled in the present study, following Kenyan guidelines, women will receive standard prenatal care, including routine daily iron and folate supplementation. We will collect venous blood samples in each trimester and at delivery, and during the first 6 months of lactation in the mothers and infants (heel prick samples). To directly assess dietary iron absorption, in a randomly selected subset of women (n=35), oral and intravenous stable iron isotope tracers (54Fe, 58Fe) will be administered in the 2nd and 3rd trimesters.

Interventions

• Other CO-rebreathing
  In the CO-rebreathing method, a dedicated apparatus is used for inhaling and rebreathing a very small bolus of CO through a spirometer for \~2 min, which is absorbed through the lungs and binds to Hb, and then the increase of HbCO content of blood is measured 8 min after the CO inhalation. The increase of COHb in blood samples can then be used to precisely calculate Hb mass and blood volume
• Other Oral iron isotope administration (54Fe)
  Participants randomly assigned to the sub-group, will receive 54Fe with a test meal in the second and third trimester for assessment of dietary iron absorption
• Other Intravenous iron isotope administration (58Fe)
  Participants randomly assigned to the sub-group, will receive intravenous 58Fe in the second and third trimester for assessment of erythrocyte iron incorporation

Primary outcome measures

• Iron absorbed, lossed and gained in the first trimester [Time frame: Change in 57Fe tracer abundance between gestational age 6, 10 and 15 weeks]
• Iron absorbed, lossed and gained in the second trimester [Time frame: Change in 57Fe tracer abundance between gestational age 15, 20 and 25 weeks]
• Iron absorbed, lossed and gained in the third trimester [Time frame: Change in 57Fe tracer abundance between gestational age 25, 30 and 35 weeks]
• Iron absorbed, lossed and gained throughout pregnancy [Time frame: Change in 57Fe tracer abundance between gestational age 6, 10, 15, 20, 25, 30 and 35 weeks]
• Iron absorbed, lossed and gained in lactating women [Time frame: Change in 57Fe tracer abundance between 6, 14 and 24 weeks postpartum]
• Iron absorbed, lossed and gained in infancy [Time frame: Change in 57Fe tracer abundance between age 6, 14 and 24 weeks]

Secondary outcome measures (12)

• Fractional iron absorption (%) in the second trimester [Time frame: gestational age 20 weeks]
• Fractional iron absorption (%) in the third trimester [Time frame: gestational age 30 weeks]
• Erythrocyte iron incorporation (%) in the second trimester [Time frame: gestational age 20 weeks]
• Erythrocyte iron incorporation (%) in the third trimester [Time frame: gestational age 30 weeks]
• Hemoglobin concentration (g/dl) [Time frame: gestational age 6 weeks]
• Hemoglobin concentration (g/dl) [Time frame: gestational age 10 weeks]
• Hemoglobin concentration (g/dl) [Time frame: gestational age 15 weeks]
• Hemoglobin concentration (g/dl) [Time frame: gestational age 20 weeks]
• Hemoglobin concentration (g/dl) [Time frame: gestational age 25 weeks]
• Hemoglobin concentration (g/dl) [Time frame: gestational age 30 weeks]
• Hemoglobin concentration (g/dl) [Time frame: gestational age 36 weeks]
• Hemoglobin concentration (g/dl) [Time frame: 6 weeks postpartum]

Eligibility criteria

Inclusion criteria

• Providing consent to the informed consent form
• Participation in a previous stable isotope absorption study and having received an oral dose of 15 mg 57Fe at least 12 months prior to the date of inclusion in the study
• Positive pregnancy test and gestational age <10 weeks based on history of last menstrual period
• Permanent residence in the study area, and not expected to leave the study site for more than 4 weeks over the following 16 months
• Assessment of good health by professional staff at Msambweni Hospital

Exclusion criteria

• Pre-pregnancy body mass index >30 kg/m2
• Blood transfusion or intravenous iron treatment within 4 months of study start
• Major chronic infectious disease (e.g., tuberculosis, HIV+, hepatitis)
• Major chronic non-infectious disease (e.g., Type 1 or 2 diabetes, cancer)

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: No

Study design

Observational model

Cohort

Study locations

Kenya · 1 center

• Msambweni Referral Hospital — Msambweni

Identifiers

NCT: NCT05973552 · PILLAR_II

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗