Obesity and anaemia: the double burden of malnutrition in pregnancy

Abstract

Obesity and iron deficiency (ID) both significantly impact women's reproductive health. Although obesity is linked to nutritional deficiencies, its impact on iron status and related pregnancy outcomes remains uncertain.

This research aimed to determine the impact of adiposity in early pregnancy on maternal and foetal iron status and explore the potential role of inflammation and epigenetic changes in iron-related genes in this association. Through an extensive analysis, using a variety of research methodologies, this research has shown a high prevalence of ID in women of reproductive age (WRA),with greater central adiposity being strongly associated with compromised iron status and iron deficiency anaemia.

Obesity was shown to negatively disrupt iron status during the first and second trimesters, in newborns, and during postpartum. BMI ≥25 kg/m2 was demonstrated as a risk factor for anaemia in late pregnancy and early postpartum period, and using a higher haemoglobin cut-off at 12 gestational weeks (GW) reduced associated complications, especially in women with BMI ≥25 kg/m2. Greater adiposity, mediated by inflammation, increased the risk of ID in the late third trimester and, soluble transferrin receptor in early pregnancy was found to be the best predictor of ID in the third trimester. Greater adiposity was associated with altered DNA methylation patterns in TfR2 and HJV at 12 GW, with inflammation being a mediator for HJV methylation. A randomized, double-blind, controlled intervention study was designed, planned and implemented to evaluate the influence of maternal adiposity on maternal iron status in response to antenatal iron supplementation (25 vs. 50 mg/d elemental iron), currently in recruitment, expected to be completed by July 2026.

Overall, this research demonstrated that excess adiposity is a risk factor for the development of ID and iron deficiency anaemia in WRA and during pregnancy,
increasing the risk of obstetric anaemia-associated complications, extending these effects on newborns and the postpartum period.

Date of Award	Nov 2025
Original language	English
Sponsors	Department for the Economy
Supervisor	Paul Thompson (Supervisor), Maeve Kerr (Supervisor), Maria Mulhern (Supervisor) & Mary McCann (Supervisor)