A 24-year-old multiparous woman (G3P2) at 28 weeks of gestation attends the antenatal clinic at a sub-centre in rural Maharashtra. She reports irregular antenatal visits (only 1 visit at 12 weeks). On enquiry, she reveals that her previous two children died in infancy from diarrhoea and respiratory infection. Her current haemoglobin is 7.2 g/dL. According to RCH protocols, which of the following is the MOST critical intervention to prevent recurrence of child deaths in her future offspring?