Following a mental and physical growth spurt, your 13-week-old baby probably seems so big, yet still so tiny. They’re more interactive and communicative than ever as they make sounds beyond just their hungry or tired cry. Before you know it, they’ll be talking and moving non-stop—so enjoy this period of infancy when their communication is slightly more sophisticated than a newborn but still far off from the demands of a threenager. Here’s what to look for in 13-week-old baby development, growth and more.

13-Week-Old Baby Milestones & Development

Growth

If your 13-week-old baby didn’t experience a growth spurt last week, it’s possible it could still happen this week. Either way, their growth will average out to a gain of about 1 ounce a day and 1 inch a month. Their head circumference will increase by another centimeter or so this month as well.

Emerging skills

At 13-weeks-old, baby is continuing to get stronger and more coordinated. Their hands are probably a great source of fascination as they open and close them, move them with greater purpose, bring them to their mouth and grasp and swat at objects. Your little one may be rolling from belly to back, or maybe just belly to side. And boy are they chatty! Okay, so it’s not like they’re ready to say words, but they’re likely babbling, mimicking sounds and beginning to participate in back and forth “conversations” with you. Hopefully you’re getting lots of good smiles; chances are, baby’s face lights up when they spot someone they know and love (aka, you!).

13-Week-Old Baby Health

Feeding

Baby’s feedings are probably getting more efficient (meaning faster) and more regular as you settle into a schedule. Of course, that schedule looks different for everyone—it all depends on baby’s temperament and appetite and your family’s routines. How much should a 13-week-old baby eat? About 4 to 5 ounces per feeding every three to four hours is still typical.

Sleep

Sleep can be a touchy subject, especially for parents who aren’t getting enough of it. Keep trying to slowly get baby on a schedule to the best of your ability, so everyone involved has some much needed predictability to the days. Each individual is different, but your 13-week-old baby should be getting around 15 total hours of sleep, with nine to 10 of those happening overnight and four to five during the day.

Common ailments

Diarrhea
If your 13-week-old baby has a loose, watery stool, there’s usually nothing to worry about. But if stools suddenly increase in number and looseness and happen three times in a row, you may be dealing with diarrhea. It’s a good idea to check baby’s temperature to make sure they don’t also have a fever, then call the pediatrician to check in. Chances are, it’s just a sign of a mild virus, but the concern at this age is dehydration, which can happen very quickly with little ones. Make sure baby continues to drink plenty of breast milk or formula and has wet diapers.

13-Week-Old Baby FAQs

What to do if baby rolls over in their sleep?

With so much focus on putting babies to sleep on their backs to help prevent SIDS, it’s no wonder parents start to worry as their little ones get closer to milestones like rolling over. So what should you do if your 13-week-old baby rolls over in their sleep from their back onto their tummy? If they’re able to roll, then stop swaddling them immediately—you don’t want baby to roll onto their face and then not be able to move. If you happen to notice that baby has rolled over in their sleep, then gently return them to their back. But don’t feel like you need to keep watch 24/7; just shift them if you happen to notice.

When can baby drink water?

The only thing a 13-week-old baby should be ingesting is breast milk or formula. Even though drinking water is important later in life, their kidneys aren’t mature enough to handle water until they’re about 6 months old. Giving baby now could actually lead to water intoxication, so hold off and keep them hydrated with breast milk or formula.

Timely 13-Week Topics

Teething signs and remedies

If your 13-week-old baby is fussy but not hungry, tired or sick, there’s a chance they’re teething: Babies tend to start teething any time between 3 and 7 months. Other signs of teething include drooling more than usual, swollen gums, loss of appetite and even a temperature slightly higher than their normal. They’ll go through bouts of teething before each new tooth erupts for the next two years or so. If baby seems uncomfortable, you can try giving them a gentle gum massage, offer baby-safe teething toys or a pacifier, since the sucking motion can help. For extra relief, try refrigerating a teething toy for a bit before offering it to baby, since the cold may feel nice on their gums. (Just don’t offer anything frozen, since that’ll be too hard on baby’s gums.) If your little one seems to be in real pain, you can consider giving them acetaminophen (Tylenol) as a last resort; be sure to measure the correct dose based on their weight. Ibuprofen should not be given to babies under 6 months old.

Reading to baby

It’s true that your 13-week-old baby can’t speak yet, let alone read. But even at this tender age, the shared activity of reading stories helps baby build brain connections and improves later language acquisition, literacy and even motor skills. If you haven’t started incorporating books into your sleepytime routine, there’s no time like the present! Start simple with a treasured picture book in the evenings before bed. Keep some board books stashed throughout your home so you can easily grab one whenever you like. Right now it’s all about making it a part of your routine.

Parent Tips

• Don’t feel the need to follow everyone’s unsolicited advice. Many things about parenthood are uncertain, but there’s one inevitability: the onslaught of well-meaning but unsolicited advice from seemingly everyone, including other moms and dads, your in-laws and your own parents. Some of it comes down to preferences, like breastfeeding on demand instead of formula-feeding. Other times it can be downright dangerous advice that probably used to be the wisdom of the day, like putting rice cereal in a newborn’s bottle or filling the crib with blankets and stuffed animals. Either way, the key is to be kind but firm if their suggestions don’t jive with your parenting approach or modern safety advice. Brush off the little stuff and politely decline what you disagree with. But also remember that they’ve been through this parenthood thing before and once in a while might have some worthwhile advice, so know when to listen too.
• Cut out cannabis if you’re breastfeeding. There’s plenty written about alcohol and breastfeeding, but with marijuana becoming legal in an increasing number of locations, many parents may wonder if they can pop an edible while lactating. The short answer: No. Whereas alcohol can be detected in breast milk for up to two to three hours before being metabolized, THC has been shown to stay in breast milk for up to six weeks—meaning it’ll be passed on to your breastfeeding child and could potentially impact their neurodevelopment. There isn’t much data on how marijuana affects babies, and the data that exists is conflicting, which is why the CDC discourages the use—and that goes for CBD products too.

Products You Need at 13 Weeks

• Teething toys. Now that baby is on the precipice of teething, it’s time to stock up on a few quality toys designed to be gummed, chewed and carelessly tossed aside. When buying a baby teething toy, look for one that’s made of a safe material such as natural rubber, BPA-free plastic, wood, silicone or even fabric. Your 13-week-old baby may have some strong preferences, so it can take a bit of trial and error before you find “the one.”
• Board books. You don’t need to go on a bibliophile shopping spree, but it’s a great time to start building up baby’s library with some beloved children’s books. Make sure you have board books in the collection that you won’t mind baby using as a teething toy!

Weekly Activity for Your 13-Week-Old Baby

Sit-ups are great for strengthening core muscles—yours and baby’s! When your little one is laying on the floor, lightly grasp their hands and gently pull them up into a supported sitting position. Baby’s body naturally works to keep their head in alignment, which helps build muscle in their neck and torso. Pro tip: As you pull baby up, get close to their face and sing, make funny noises or give lots of kisses. Your little one will love the one-on-one attention and emotional bonding time!