GSTM1 and Iron deficiency anemia: Secondary outcomes include: motor and language development assessed by Bayley-III Motor (MotCS) and Language (LangCS) Composite Scores (+6 months, +12 months), behaviour assessed by WBR, temperament, growth assessed by weight-for-age z-score, length-for-age z-score, weight-for-length z-score, head circumference z-score, anaemia (Hb<11 g/dL), Hb concentration, iron deficiency (ferritin <12 ng/μL adjusted for inflammation assessed by CRP or AGP), ferritin concentration and iron deficiency anaemia.