Most infant formula milks are derived from cow’s milk, but they have been modified in order to resemble breast milk as closely as possible. It's a good idea to discuss the different brands with your midwife or health visitor, before deciding which to use.

There are two main types of infant milk, and each has different ratios of two proteins in milk: whey and casein. Those that are suitable for babies from birth contain more whey than casein. The ratio of whey to casein in these milks is similar to that of breast milk, and this is why it is thought to be easier for new babies to digest.

Milks which are often marketed as being for the ‘hungrier’ baby contain more casein than whey and take longer to digest. If your baby does not seem content with the formula you first started her on, talk to your health visitor or GP before changing to a casein-based formula.

It is important that you do not give your baby doorstep cows’ milk as a main milk until he is at least one year old, because he would not be able to digest the extra protein and salt that it contains.

There are other specialised milks available for particular needs:

• Soya formula, which is useful if your baby has a cows’ milk intolerance, but should only be used on the recommendation of your midwife, health visitor or GP

• Pre-term formula, for small or premature babies

• Follow-on milks, intended for babies over six months, and which contain added vitamins and minerals

Most formula milks are dried and packaged in tins. They can also be bought ready-made, which is an expensive option, but can be useful for holidays or days out.

More information on baby milks