Choose a formula that's right for you...

Milk-based formula
Cows' milk is the standard base for infant formula. Manufacturers modify cows' milk for human babies by adjusting carbohydrate, protein, and fat levels and adding vitamins and minerals (most milk- and soy-based formulas provide 20 calories per ounce). The quality of traditional infant formula has improved tremendously in the last decade. However, researchers have yet to reproduce the unique qualities that make breast milk the ideal food for babies.
  
Soy-based formula
Soy protein is plant-based from soybeans and, like cow's milk, is modified for use in formula with vitamins, minerals, and nutrients. While some experts  and parents swear by soy, others say it may lack some compounds such as amino acids that help a baby thrive.
  
Infants who are allergic to lactose, a sugar found in cows' milk, may be less sensitive to soy-based formula. However, up to half of all allergy-prone babies also react negatively to soy and may fare better with a special hypoallergenic formula (see below).

Experts have no evidence that soy-based formulas can help soothe a colicky baby.
 
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Which is better - formula with or without iron?
 
Both cow's milk and soy formulas are available in low iron (less than 6.7 mg/L; usually between1.5 mg/L and 4.5 mg/L) and iron fortified (from 4 to 12 mg/L) varieties. Babies who are not breastfed or who are partially breastfed should be given an iron fortified formula from birth to 12 months. Breastfed babies absorb more than 50 percent of iron from human milk, about 12 percent from cow's milk formula, and up to 7 percent of soy formula. Experts agree that the fortified formulas sufficiently boost iron levels in babies and young children.
 
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What are hypoallergenic and follow-up formulas?

You may notice specialty formulas labeled hypoallergenic or follow-up on the shelves of your local supermarket or pharmacy. These formulas are designed for babies with specific medical or nutritional needs, so ask your healthcare provider before using one. Here's the lowdown:
  
Hypoallergenic formulas
These formulas are designed to trigger fewer allergies and be easier to digest than standard varieties. Experts know less about them than traditional blends, and since they are relative newcomers to the market, their long-term effects on babies are still being evaluated. One thing's certain: Hydrolyzing, the process used to make the formula more digestible, also leaves it tasting bitter, even after sweeteners have been added. Specialty formula also tends to be saltier than soy- and milk-based products - and four to five times more expensive.
   
Follow-up formulas
These formulas are specifically designed for babies 4 to 12 months old who are already eating some solids. Follow-up formulas contain more calcium, iron, protein, and calories than infant formulas. They're often a bit cheaper too. Most doctors encourage parents to introduce solid foods (baby cereal, pureed fruits and vegetables) to their babies at around 6 months rather than have them fill up on formula. But it depends on the individual child. Babies with food allergies, those who are very sensitive to different foods, and those with a history of poor growth may benefit from follow-up formula.
   
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Formula Dos and Don'ts

• Do use formula before the expiration date on the label.
• Do prepare formula exactly as stated on the label. Formula that is too weak or diluted can stunt growth or lead to nutritional deficiencies. Formula that is too strong can lead to dehydration or kidney problems.
• Do wash your hands before handling baby bottles or feeding your baby.
• Do ask your pediatrician if bottles and equipment need to be sterilized.
• Do use refrigerated ready-to-feed or prepared formula within 48 hours of opening.
• Do throw away any formula left in a bottle after a feeding. Germs and bacteria from your baby's saliva will live and breed in the warm liquid.
• Do refrigerate unused, but prepared, formula.
• Do ask your pediatrician or healthcare provider about adding fluoride supplements to your baby's formula. Ready-to-use formula is fluoride-free, so unless your water supply has added fluoride, you'll need to use supplements.
• Don't heat formula in a microwave. The temperature of the liquid may be uneven, and could scald your baby even if the bottle feels cool to the touch.
• Don't leave bottles of formula out of the refrigerator for more than two hours.
• Don't put cereal in a bottle - it makes choking more likely.
• Don't let your baby fall asleep while bottle-feeding. The sugar in formula can collect on his teeth and cause tooth decay.
• Don't prop your baby's bottle - it increases his risk of choking. Also, drinking while lying down can force formula from your baby's throat through his Eustachian tube and into his middle ear, making an ear infection more likely.