Iron in pregnancy halved anaemia without changing how births went
Across 23 studies and 4,492 women who started out not anaemic, iron cut the chance of becoming anaemic by half. Birth weight, preterm birth and caesarean rate were unchanged.
What the study found
Iron in non-anaemic pregnancy halved anaemia and moved nothing else
Pooled across 23 studies and 4,492 women who were not anaemic to begin with, routine iron cut the chance of becoming anaemic during pregnancy by half, with ten women treated per case prevented. Birth weight, preterm birth and caesarean rate were all unchanged.
The caveat · Mixes trials with observational data
The review mixes randomised trials with observational studies. Its haemoglobin and ferritin figures came out with heterogeneity of 91% and 87%, which makes those pooled numbers too unstable to quote as point estimates. What is left is a benefit measured in blood tests and a diagnosis avoided, not in how the pregnancy or the baby turned out.