Another week has flown by, and at 9 weeks, baby just keeps getting cuter as their personality shines through more and more. They’ve probably got you wrapped around their little finger with that smile of theirs, and you may melt every time they gaze deep into your eyes. Keep looking and smiling at your 9-week-old baby to continue strengthening your relationship, deepening their feeling of security and supporting their development. Many parents start to get out more with their baby, now that they’re farther along in their development and have another round of protective vaccines under their belt. So what can you expect this week? Read on for more information on 9-week-old baby development, milestones and more.

9-Week-Old Baby Milestones & Development

Growth

Baby will likely grow about 1 inch in length and 2 pounds in weight this month, but these are just averages rather than strict guidelines. And it’s not constant; there will be some weeks where they grow more than others. At last week’s well visit you should have gotten a good idea of how baby is growing and where they fall in terms of percentiles. As long as they continue along their own curve, it’s all good.

Emerging skills

We have good news for parents of colicky babies: Research says that after this week, the amount and duration of crying is bound to decrease significantly. Can we get a hallelujah? This week they’ll also continue building skills you’ve probably already seen from them like smiling, following sounds and objects with their eyes, holding their head up for longer and making noises other than fussing or crying. All these seemingly little advancements help baby make sense of their world as they start to make true connections; they pave the way for later milestones, like understanding cause and effect and object permanence.

9-Week-Old Baby Health

Feeding

Not much has changed from last week in the eating department, though baby’s timing may be getting more predictable. How much should a 9-week-old baby eat? Around 4 to 5 ounces of formula every three to four hours is typical. Breast milk is, of course, harder to measure. When in doubt, take note of their diapers; if they have at least five wet diapers a day, then they’re probably getting what they need. If they have excessive spit up or gas pains, they could potentially be eating too much. For those who are bottle-feeding, try to keep it under 32 ounces in a 24-hour period.

Sleep

Babies are born with a weak circadian rhythm, which is one of the reasons why their sleep is so erratic. But as the weeks go on, the systems responsible for solid sleep and a rhythm of day and night develop. While it’s still unlikely that baby will sleep a full night, the building blocks are, well, being built. It’s also important to note that at this age, sleeping through the night actually means five to six hours of uninterrupted sleep, not the eight or more that adults usually think of. The total amount of sleep for a 9-week-old baby in a 24-hour period should be 14 to 17 hours. But of course, each child is different, and no one knows them better than their parents.

Common ailments

Thrush
If you notice white spots in baby’s mouth, they may have thrush. This yeast infection is fairly common, especially in breastfed babies under 6 months old. Since the mouth is warm, dark and moist, it’s a perfect place for yeast to thrive—and since baby’s immune system isn’t fully formed, they’re more prone to infection. It’s especially common after baby or a breastfeeding parent has been through a round of antibiotics, since they can kill the good bacteria that help keep bad bacteria at bay. Babies with thrush also may get diaper rash. If you’re concerned that your 9-week-old baby has thrush, consult your pediatrician. It usually goes away on its own after a few days, but it can also be treated with antifungal medicine for their tongue and for Mom’s nipple, if it’s affected. (In the meantime, sterilize baby’s bottle nipples and pacifiers.)

9-Week-Old Baby FAQs

How far can a 9-week-old baby see?

At this stage of development, a baby at 9 weeks old should be able to see at least 12 inches away. Previously, their eyes weren’t always able to work in unison and may have even seemed cross-eyed at times. But by now, baby’s eyes should have strengthened so that their eyes work well together, helping them to see things even more clearly. If their eyes still appear crossed, get stuck in a certain position or aren’t tracking objects, it’s worth mentioning to the pediatrician.

What temperature should baby’s bath be?

Around 100 degrees Fahrenheit is ideal. Knowing that babies get cold easily and have trouble regulating their temperature, it can be tempting to make the bath too warm—or those who fear burning their baby may make it too cold. Aim for warm but not hot, with just a few inches of water in the tub. Keep the air temperature in the room warm as well, so baby doesn’t catch a chill while you’re drying them off.

Timely 9-Week Topics

Car seat safety

You managed to install baby’s rear-facing car seat, but that’s only part of keeping baby safe in the car—it’s also critical to strap them in properly. You should thread the harness straps so that they’re at or below baby’s shoulders, and the five-point chest clip should be in line with baby’s armpits. The harness should also be snug; if you can pinch the straps at their shoulders, it’s too loose. Because a proper fit is so important, baby shouldn’t wear any overly bulky or puffy clothing under the harness, like winter jackets. If you were to be in a crash, the fluffy padding would flatten out from the force, leaving extra space under the harness for baby to slip around.

The ideal temperature for baby

It can be oddly stressful figuring out how to dress a baby so they aren’t too hot or cold, especially in summer and winter when temperatures are in the extremes. Experts suggest keeping baby’s room at a temperature of 68 to 72 degrees Fahrenheit. As far as dressing your 9-week-old baby, the general rule of thumb is to put them in one more layer than what you’re wearing. On a hot evening, a diaper and swaddle may be sufficient, whereas cooler nights may call for fleece footy pajamas. During summer days, go for a single layer of light fabrics, while in the winter, layers and a hat are your best bet.

Parent Tips

• Bring baby in tow. Here’s a truth that many parents don’t realize until their babies are mobile: Infants are super portable, and now is actually the easiest time to bring them places. At this age, you can still wrap baby in a carrier or put them in a stroller or car seat and head out. You aren’t yet beholden to a strict schedule, so if your 9-week-old baby naps on the go at odd times here and there, it’s not going to throw everything out of whack. Plus, they don’t need a ton of entertainment; looking at the new sights and hearing new sounds will be plenty to keep them engaged. So get out of the house to see family, meet a friend or go on a trip.
• Start a breast milk stash. If you’re breastfeeding and are preparing to go back to work in the coming weeks, it can be a good idea to start pumping and freezing milk so you can build up an extra supply. Try pumping in the morning after you nurse, since that’s when many moms produce the most. As long as you leave about an hour before baby’s next feed, you should have plenty of milk to go around. As for how much to stash, well, that’s really up to you. If you’re heading back to work, you may want about three to four days worth in the freezer.

Products You Need at 9 Weeks

• Breast pump. If you were planning to breastfeed, chances are you picked out a breast pump before the baby was even born—but if not, that’s okay. Or maybe you have one but decided you’d like to add a hands-free or portable option to your selection. There is certainly no shortage of options to choose from. Also be sure to check in with your health insurance provider, as they often cover the cost of certain pumps.
• Milk storage bags. If you’re getting into the swing of pumping, then you’re going to need milk storage bags to freeze your stash. There are a number of great options on the market with extras, like the ability to connect directly to a pump.
• Pumping bra. Another helpful item for pumping parents is a pumping bra that holds your flanges in place, so you can use your hands for something else while you express breast milk. It can be a total game-changer!

Weekly Activity for Your 9-Week-Old Baby

Want to entertain baby and strengthen their muscles at the same time? A simple and fun activity you can do with your 9-week-old baby is to bicycle their legs. Lay baby on their back on a comfortable surface, take one of their feet in each of your hands and move their legs around as if they were riding a bike. While doing this you can smile, sing and even explain what you’re doing out loud. You can vary your speed, though always keep it gentle and smooth. This will help them develop body awareness and strengthen those leg muscles, paving the way for later gross motor skills and mobility. Plus, as an added bonus, it’ll also help relieve any gas that’s stuck in baby’s belly.