GSTM1 and anemia (phenotype): Fig 1 presents the distributions of Hb for non-pregnant participants in each phase of the study. In 2010 (phase 2), anemia prevalence (40% = 19/48 women) was 50% higher than the national average for non-pregnant Bolivian women (26.4% in 2002 [4]). Furthermore, anemia prevalence in phase 2 was only 8% less than that observed in phase 1 (48% = 86/181 women), a difference that may be partly attributable to aging of these study participants in the intervening years and the fact that anemia is generally lower in older women [27].