Switch 'Em UpMyth #3: Babies should nurse about the same time on each breast at each feeding.
Fact: New mothers are often advised to nurse their infants for "10 to 15 minutes on each side," which implies that feedings should be timed and that babies take about the same amount of milk from each breast at each feeding, which is seldom true. Not only do individual babies display highly variable breastfeeding styles, but the same baby can have different nursing patterns, depending upon whether she is ravenously hungry or nursing for comfort.
Babies don't take equal amounts of milk from each breast at a feeding -- most infants nurse more vigorously at the first breast and obtain about two-thirds of the milk for the feeding from that side. Because less milk is taken from the second breast, it's recommended to alternate the side on which feedings are begun. Although the milk a baby obtains at the beginning of a feeding is relatively low in fat, the fat content steadily increases throughout the session. So it's important to nurse on the first breast until it's well-drained (for at least ten minutes) to give your baby access to the rich, high-fat hind milk.
Some experts recommend staying on one breast for the whole feeding to get more of the hind milk, but I've found the majority of infants thrive best when nursing from both breasts. This is because your baby can get the greatest amount of milk within the first ten minutes on one breast. When she starts to suck less vigorously on the first side or begins to doze off, you can burp her, change her diaper, and arouse her for the second side. Let her stay on this side as long as she wants, although she will likely drain less milk and may fall asleep.
As babies get older and the milk ejection reflex (the "let-down") becomes well conditioned, many learn to nurse very efficiently, taking the bulk of their feeding in only four to seven minutes per breast. If you'd like to leave her on one breast longer to access more hind milk, then give it a try. But if there's any concern that your baby isn't eating enough, it's more important to switch to the second side for the greater volume of milk.
Talk to your doctor or lactation consultant if your baby has either very brief (less than 10 minutes total) or very long (more than 50 minutes) feeding sessions, as either may be cause for concern.