Life is sweet with a 15-week-old, who is probably charming loved ones right now with lots of smiles and making eye contact to hold your attention. Babies at 15 weeks are typically super active, pushing up on their tummies and maybe even rolling from belly to back. Wondering what other milestones and developmental changes you can look forward to? Here’s everything you need to know about your 15-week-old.

15-Week Old Baby Milestones & Development

Growth

At 15 weeks old, babies have typically doubled their birth weight. Baby boys in the 50th percentile—meaning that 50 percent of babies of the same age and sex weigh more and 50 percent weigh less—are about 14.8 pounds, while girls are hovering around 13.4 pounds. The average length (aka height) is around 24.6 inches for boys and 24 inches for girls.

It's totally normal if your child doesn’t stack up to these numbers. Remember that healthy babies follow their own natural growth curve, and that weight, height and head circumference percentiles are just tools to help the pediatrician pinpoint where baby is headed, growth-wise, in the years to come.

Emerging skills

Hello, hands! Having just discovered their hands and how they move, your 15-week-old is full of action, batting, grabbing and gripping toys that you give them. They can probably hold their head up without support, which means they’re a lot more fun to walk and dance with. Your little one is probably getting much more vocal too: Expect lots of cooing and babbling now and in the weeks to come.

15-Week-Old Baby Health

Feeding

How much should a 15-week-old baby be eating? On average, breastfed babies are likely to eat about eight times a day, adding up to roughly 25 ounces in a 24-hour period.

Formula-fed babies are typically eating every three to five hours and may take in up to 6 or 7 ounces over five or six feedings in a 24-hour period. Though your 15-week-old may seem hungrier than normal—growth spurts around 4 months of age are real—resist the urge to start feeding baby cereal right now. The American Academy of Pediatrics recommends waiting until baby is 6 months old before introducing solid foods, though depending on your child, some pediatricians may say that 16 weeks is an okay time to start.

Remember that infant feeding is a continuum over the first year of life. There are days when baby won’t seem very hungry and days when they can’t get enough. As long as the pediatrician is happy with how they’re growing, eating in fits and starts is totally normal.

Sleep

Your 15-week-old, suddenly more aware of the world around them, is likely awake for longer stretches during the day and may have dropped down to two or three naps. At night, most babies this age can sleep a good chunk of time (maybe five or six hours) without needing a feeding at night, although that doesn’t necessarily mean baby won’t still want one. Your pediatrician can confirm.

All in all, babies at 15 weeks old need between 14 and 16 hours of sleep in a 24-hour period; aim for nine to 10 hours at night and two or three naps per day ranging from 30 minutes to two hours each.

15-Week-Old Baby FAQs

When do babies start to laugh?

It could be coming very soon! There’s a wide age range for when babies laugh, but around 4 months is when many babies start giggling and chuckling. For that full-throated belly laugh, you may have to wait until closer to 6 months.

Why is my 15-week-old refusing their bottle?

The most common reason why babies won’t take a bottle is simply that they’re not hungry, research shows. If previously breastfed, some babies may want to go back to the breast. Or, they simply don’t like the temperature, taste or texture of the milk. If baby is refusing the bottle consistently, consult their pediatrician on next steps. Something to keep in mind if you’re feeding baby breast milk that was previously frozen: Sometimes storing the milk can change the taste for the worse. Experimenting with how you store it may help.

Timely 15-Week Topics

Upcoming shots

At their upcoming 4-month checkup, baby is due to receive a round of second-dose immunizations to help protect against the following diseases:

• Diphtheria, tetanus, and whooping cough (DTaP)
• HiB disease (Haemophilus influenza type b disease)
• Polio
• Pneumococcal disease
• Rotavirus
• Hepatitis B

We’re not going to lie: It’s a lot of shots (that will all help keep your little one safe!). You may need to soothe baby after their vaccines; side effects like a rash, soreness at the injection site, fever and fussiness are common. Baby might also eat a little less in the next day or so, sleep a little more and feel warmer than usual. A cool, damp cloth held to the injection site helps reduce soreness, and a cool sponge bath can help a low-grade fever. Call your pediatrician with any concerns.

Baby drool

Is baby’s mouth just constantly dripping? While constantly laundering baby’s bibs can be a bit of a pain, drooling and blowing bubbles is super common at this age; drool typically peaks between 3 and 6 months of age. It’s actually a good thing: Drool is a sign of a developing digestive system. Salivary glands produce 2 to 4 pints of silva a day, but because babies don’t yet have full control over the muscles in their mouth and haven’t mastered the act of swallowing, some of that saliva tends to spill out. Plus, while adult teeth can act as a dam for our saliva, babies don’t have the same benefit. If you’ve noticed a sudden increase in baby’s drooling, it could also be a sign that a new baby tooth is on its way!

Parent Tips

• Take some time to be present. The days of caring for an infant can seem long, but the months go quick. Give yourself permission to block out the world and say no to other obligations so you can take 15 minutes—or an hour, or two—to spend bonding time with baby. Read aloud to your little one, dance and sing with them or just pick them up for a long hug. You can never spoil your infant with love.
• Take time for yourself. While having one-on-one time with baby is important, it’s just as essential to regularly carve out time for yourself, with the help of your support system—be it a partner, family members, loving friends or an available sitter. Take a nap, exercise, go out on a date, engage in a hobby—anything that places all your attention on yourself. Self-care helps you replenish your energy, focus and positivity, which benefits everyone around you, including baby!

Products You Need at 15 Weeks

• Blackout curtains. Now that baby’s circadian rhythms have started to develop, it’s helpful to keep baby’s room dark during nap and nighttime to signal to their body that it’s time for sleep. We love these light-blocking curtain options.
• Drool bibs. At this age, baby is probably proving to be a bit of a slobber monster. Developmentally, drooling tends to peak between 3 and 6 months. To keep your little one’s shirts from getting soaked, stock up on a few cute bibs and bandanas.

Weekly Activity for Your 15-Week-Old Baby

It’s never too early or too late to read to baby. Not only is reading aloud to your 15-week-old on your lap a wonderful way to bond emotionally, but hearing the cadence of words in a book is a big part of babies’ language development. Also, consistently reading to them as part of the bedtime routine is a relaxing way to signal that it’s almost time for sleep.