They are now the healthy start vouchers, you have to fill out application pack:
https://www.healthystart.nhs.uk/
£3.10 a week if you're pregnant
£6.20 a week for each baby aged under one
£3.10 a week for each child aged over one and under four
spend in asda/tesco etc on veg/fruit/frozen veg and fruit, milk and baby milk.
also vouchers for free vitamins