GSTM1 and anemia: The present study was powered to detect an effect of −0.31 z-score on birth weight in 2nd trimester severe anaemia (Hb ≤ 8 g/dL) with a significance level of 0.05, a power of 0.80, and an assumption of 15% lost to follow-up based upon previous observations in the STOPPAM study [38].