Soya-based formula is made from soya beans which, like cow's milk, are modified for use in formula with vitamins, minerals, and nutrients. Babies should only be given soya-based formula on the advice of a health professional, such as a health visitor, GP or dietitian.

Which brand should you buy?

Pediatrics does not endorse or recommend any infant drink any specific brand of formula if you choose not to breastfeed, except they do say that low iron formula should not be used.

And convincing studies have not been done to show that any one brand is better for your baby than another.

So which brand you choose is something that you will have to decide for yourself.

Which formula is right for your baby?

Once you choose a brand of formula, you will have to decide which type of formula you want for your baby.

It might help you choose if you understand what makes each type of formula different.

Infant formulas mostly differ in the type of sugar and protein that they have.

Regular iron fortified infant formulas are made with lactose and cow's milk based proteins. Most infants who are not breastfeeding exclusively should be given a cow's milk based iron fortified formula.

Soy formulas are made with soy protein and are lactose free. They are good for children who don't tolerate lactose or milk proteins.

Elemental formulas are also lactose free and are made with hydrolysate proteins, which are easy to digest for infants with protein allergies. Types of elemental formulas include Nutramigen, Pregestamil and Alimentum.

If you have a family history of food allergies or formula intolerances, you might choose to start your baby off with a soy or elemental formula if you do not want to breastfeed.

Lactose free formulas are made without lactose, but do have cow's milk proteins in them. Infants are not usually thought to be born with a lactose intolerance, so these formulas are usually not needed.

Powder, Concentrate or Ready-To-Feed?

When choosing a formula, you will also have to decide if you would like to buy your formula as a powder or concentrated liquid, which you will have to mix, or a ready-to-feed or ready-to-use formula. In general, ready to feed formula, while more convenient, are more expensive. Powder formula is usually the least expensive.

You can also buy some brands of formula which is pre-measured to make a 4 ounce bottle.

DHA and ARA

This past year, new infant formulas were introduced which are supplemented with DHA and ARA, which are found in breast milk and are thought to help with an infant's development.

Soy formulas and premature formulas with DHA and ARA have also been introduced.

A formula with DHA and ARA is likely a good choice if your infant isn't breastfeeding and you want to give a formula that is most like breast milk to help with their development.

What are "follow-on" milks?

"Follow-on" milks are milks with higher protein and mineral content than ordinary infant formula. They are suitable for babies over six months old, and are advertised as a more nutritious milk than cow's milk. However, many experts recommend meeting your child's increasing nutritional needs as she grows by giving her more of her standard formula milk, whilst making sure that the solids part of her diet to include more calcium and iron-rich foods.

If you would like to use a follow-on milk, you may be interested to note that you can also buy organic varieties.