In a multivariable regression analysis Hb levels remained an independently associated parameter for GDM after adjusting for two (Model 1), six (Model 2) or seven (Model 3) of the most relevant covariates, Model 3 being adjusted for smoking, the gestational week Hb was measured, maternal age, parity, pre-pregnancy BMI, maternal educational attainment and hypertensive disorders (Fig. 2a, Table S2). The gene discussed is GSTM1; the disease is gestational diabetes.