04/15/2026
There is a time and a place for iron supplements in pregnancy, but not everyone needs supplementation.
In fact, studies are now showing that supplementing with iron in replete patients may actually cause HARM.
Why?
Iron is oxidative.
Higher ferritin and iron levels are consistently associated with higher GDM risk in both cohort and case-controlled studies.
Cut offs range from 45 – 100 in studies, with first‑trimester ferritin persistently above ~50 ng/mL, and especially above ~70–80+ ng/mL, being associated with higher GDM risk later in pregnancy.
💥Cohorts with higher average ferritin (means ~65–77 ng/mL) carried a ~2-4x higher risk of GDM
💥A large (2025) Chinese cohort found “high” ferritin defined by quintiles; median first‑trimester 57.7 ng/mL, with GDM risk rising steadily across quintiles
💥Meta-analyses show women with GDM have higher ferritin/iron and that GDM odds rise with ferritin; each 5 µg/L ferritin increase raised GDM risk by ~2–3%
💥Across cohorts, longer‑term iron doses >30 mg/day, especially ≥60 mg/day in early and mid‑pregnancy, typically raise GDM risk by ~30–130%, with larger effects when women are already iron‑replete (high/normal ferritin or Hb).
Testing ferritin in first trimester is crucial to prenatal care, let's start adding this to our prenatal screenings.
Studies:
👉🏼https://pubmed.ncbi.nlm.nih.gov/37324369/
👉🏼https://pubmed.ncbi.nlm.nih.gov/31932742/
👉🏼https://pubmed.ncbi.nlm.nih.gov/39885420/
👉🏼https://pubmed.ncbi.nlm.nih.gov/40313887/
👉🏼https://pmc.ncbi.nlm.nih.gov/articles/PMC8180699/
👉🏼https://pubmed.ncbi.nlm.nih.gov/32755052/
👉🏼https://pubmed.ncbi.nlm.nih.gov/34019623/
