Of the 115 women with Hb < 12.6 g/dL during the first trimester, 39 (34%) developed anemia during the third trimester, while only 8 of 116 (6.9%) with Hb ≥ 12.6 g/dL during first trimester developed anemia during the third trimester. Here, GSTM1 is linked to anemia.