Growth Spurts

During a growth spurt, breastfed babies nurse more often than usual (sometimes as often as every hour) and often act fussier than usual.
The increase in baby’s milk intake during growth spurts is temporary. In exclusively breastfed babies, milk intake increases quickly during the first few weeks of life, then stays about the same between one and six months. As solids are gradually introduced after six months, baby’s milk intake will gradually decrease.
Definititon-Most babies go through several growth spurts (also called frequency days) during the first 12 months.
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When do babies have growth spurts?

Common times for growth spurts are during the first few days at home and around 7-10 days, 2-3 weeks, 4-6 weeks, 3 months, 4 months, 6 months and 9 months (more or less). Babies don’t read calendars, however, so your baby may do things differently.
Growth spurts don’t stop after the first year – most moms notice growth spurts every few months during the toddler years and periodically thereafter on through the teenage years.

How long do growth spurts last?

Growth spurts usually last 2-3 days, but sometimes last a week or so.

What is the best way to handle a growth spurt?

Follow your child’s lead. Baby will automatically get more milk by nursing more frequently, and your milk supply will increase due to the increased nursing. It is not necessary (or advised) to supplement your baby with formula or expressed milk during a growth spurt. Supplementing (and/or scheduling feeds) interferes with the natural supply and demand of milk production and will prevent your body from getting the message to make more milk during the growth spurt.
Some nursing moms feel more hungry or thirsty when baby is going through a growth spurt. Listen to your body — you may need to eat or drink more during the time that baby is nursing more often.
See My baby is fussy! Is something wrong? for tips on comforting a fussy baby.