Asking if a baby is having a growth spurt is like asking if a sloth is having a tired spell. It’s kind of what they do. Babies grow much faster in their first year of life than at any other time except in utero. A typical school-aged child grows about 2 inches each year. During puberty, that number spikes to 4 inches. In the first 12 months, the average baby sprouts a whopping 10 inches.
Even within this busy growing season, some babies experience short bursts of rapid height and weight gain. Every child is different, so it’s impossible to say if or when these “spurts” will occur, says Clare Bush, M.D., assistant professor of pediatrics at Columbia University Medical Center. She often sees a small growth spurt when a newborn is 7 to 10 days old: “The babies have learned to breastfeed, moms have learned to breastfeed. Things are happening a little more smoothly.”
There may be another spike around the one-month mark. But pediatricians tend to look at other benchmarks: Is the baby doubling her weight at 4 months? Tripling it at a year? Generally progressing along her own growth curve?
Leigh Anne O’Connor, a board-certified lactation consultant with a private practice in New York City, says she commonly sees growth spurts around 3 weeks, 6 weeks, 3 months, and 6 months of age. But the best gauge is your baby.
How to tell if your baby is particularly busy packing on the ounces during a growth spurt. Here are the signs to watch for:
1. Your baby is constantly hungry.
Just when you think you’ve figured out a feeding schedule, your baby suddenly wants to eat around the clock. In a breastfed infant, this might mean two to four days of marathon nursing. A formula-fed baby might be dissatisfied after finishing a bottle.
“Everything is revved up in the first year of life. The metabolism is quick, the frequency of needing feeds is quick,” says Dr. Joshua May, a pediatric endocrinologist at Los Angeles Medical Center at Kaiser Permanente. “Those calories are going toward growth, whether it be building reserves of fat cells or building muscle or—with the help of hormones—actually physically changing the structure of bones.” Helpful perspective when on-demand feeding gets rough.
2. Your baby’s sleep patterns shift.
Some parents report that their babies sleep more during growth spells, while others report their babies sleep less, says Dr. Bush. One thing is certain: Sleep plays a vital role in the production of the primary growth hormone, aptly named “growth hormone.” So let snoozing babes lie while nature takes its course of slowly robbing you of the wee creature you once held in the crook of your arm.
3. Your baby is fussier than usual.
This could be a byproduct of the first two signs; an extra hungry or tired baby will usually tell you about it. Do babies experience growing pains? “I think it stands to reason that if there’s major growth going, that tendons and muscles are being stretched in the body and that might be associated with some pain,” says Dr. May. “We certainly see that all the time in the older age range.”
4. Your baby has mastered new tricks.
Okay, it’s a bit of a stretch to link your child’s newfound ability to clap or grasp a toy with one specific growth spurt. But a baby’s brain physically enlarges along with the rest of her body as she learns to navigate the world, causing her skull to grow and fuse in turn. That’s why a baby’s fontanelle, or “soft spot,” is closed or nearly closed by age one, says Dr. May.
Note that growth spurts, like teething, are easy to confuse with other issues. An overly sleepy or fussy baby could indicate illness, while constant hunger could indicate a low milk supply. If your baby is peeing and pooping well, you can assume supply is not an issue and take comfort in knowing the feeding frenzy will pass.