When analyzing the changes of Hb levels during the three trimesters in 10 random beta thalassaemia trait mothers who had undergone blood transfusions (Fig 1) all of them had started their pregnancy with disproportionately low Hb levels and showed a further decrease in Hb levels at the end of the second trimester, followed by a proportionate increase in the third trimester. Here, GSTM1 is linked to beta thalassemia.