Week 17

Days 113 to 119 · 16 weeks 0 days to 16 weeks 6 days old · about 4 months By now your baby measures about 62 cm (24.5 in) and weighs roughly 6.6 kg (14.5 lb). Babies vary widely, and what matters is a steady path along their own growth curve. Many babies are close to 4 months old and full of new skills: rolling or nearly rolling, reaching and grabbing with intent, laughing and watching everything around them. For you, life may be shifting towards a new routine with work, childcare or simply more time out of the house. This week looks at baby gear and rolling, distractible feeding, when to keep a sick baby home, sharing nights after a return to work, feeding while you are apart, mirror play and getting ready for the 4-month check.

Day 113 · 16 weeks 0 days old

Baby gear and a baby on the move

Once your baby starts to roll, wriggle and push off with their feet, the equipment that kept them safely in one place starts to need more care. Many injuries at this age happen when gear is used in the wrong place or without its straps, not because it is faulty.

Bouncers and baby seats can creep across a surface as your baby kicks, so always keep them on the floor and use the harness, even for a minute. Never put a car seat on a bed, sofa, table or shopping cart seat where it can tip. Strap your baby into the stroller every time.

Swings, bouncers, car seats and loungers are not safe places for sleep. If your baby falls asleep in one, move them to their crib or bassinet, flat on their back. Babies sleeping in a semi-upright position can slump forward, which can block the airway.

If your baby now rolls onto their tummy during sleep, keep putting them down on their back. Once they can roll both ways easily, it is fine to let them find their own position. Keep the crib bare: no bumpers, pillows, toys or loose blankets.

Check anything secondhand for recalls and missing parts, and follow the age and weight limits in the instructions.

Try this: Look up the model numbers of your baby's main pieces of gear and check them against your country's product recall list.

Day 114 · 16 weeks 1 day old

The distracted feeder

You settle in for a feed and, after a few sucks, your baby pops off to look at the door, the dog, the light or your face. They latch again, then stop to smile or grab your shirt. This is one of the most common feeding complaints at around 4 months, and it is a sign of healthy development.

Your baby's world has suddenly become far more interesting. Their vision is sharper, they recognize familiar people and sounds, and every noise is worth a look. Many also become very efficient at feeding by now and can take what they need in a few minutes.

To make feeds smoother, try a quiet, dimly lit room with fewer distractions for some daytime feeds. Feed when your baby is just waking and sleepy. Some parents find a nursing necklace or a toy to hold keeps busy hands occupied. Breastfeeding parents may notice that night feeds become more important, as babies make up for short daytime feeds.

Keep an eye on the overall pattern rather than single feeds. Plenty of wet diapers, regular bowel movements and steady weight gain mean your baby is getting enough.

Call your baby's doctor if your baby has far fewer wet diapers than usual, seems listless, is losing weight or refuses most feeds for more than a day. Try this: Choose one daytime feed and take it to a quiet room with the lights low and your phone left behind.

Day 115 · 16 weeks 2 days old

When to keep a sick baby home

Once your baby is in childcare, you will soon face the morning question: is my baby well enough to go? Most childcare providers have a written illness policy, and it is worth reading before your baby gets sick.

In general, babies are asked to stay home when they have a fever, vomiting or diarrhea, an unexplained rash, an eye infection with discharge, or when they are too unwell to take part in the day and need more care than the staff can give. Many places also ask that babies stay home for a set time after the fever has gone or after starting certain medicines. A runny nose on its own is often fine.

Keeping a sick baby home helps them rest and protects other children and staff. It also helps to have a backup plan before you need it. Think about who could step in if your baby cannot go: a partner, relative, friend or neighbour, or whether you can work from home or take leave.

Good handwashing, for everyone in the family and at childcare, is one of the best ways to cut down on the number of illnesses passing around. Keep up with your baby's vaccines, which protect against many serious infections. Try this: Read your provider's illness policy and write down two people you could call on a day your baby has to stay home.

Day 116 · 16 weeks 3 days old

Sharing the nights when you both work

The way you handled nights during leave may not work once one or both of you is back at work. Someone with an early start, a long commute or a job where mistakes matter needs enough sleep to function, and so does the person caring for the baby all day.

Talk it through openly rather than letting resentment build. Some families take turns, each covering every other night so one person gets a full night of rest. Others split the night into shifts, such as one person covering until 2 a.m. and the other after that, with earplugs or a separate room for the one off duty. A breastfeeding parent can still share the load: a partner can do diaper changes and resettling, or give a bottle of expressed milk or formula for one feed.

Weekends can be used to catch up, with each adult getting one morning to sleep in. Single parents may need to ask for help more directly: a relative who stays over one night a week, or a friend who takes the baby for a morning so you can nap.

Revisit the plan after a couple of weeks. What works at 4 months may need changing at 6.

For your partner: Offer to take a full night or a fixed shift this week, and protect your partner's sleep completely during that time.

Day 117 · 16 weeks 4 days old

Feeding your baby while you are apart

When your baby starts childcare, you will decide what they drink while you are away. Some families send expressed breast milk, some send formula and many combine the two. All of these can work well, and the best choice is the one that suits your baby, your body and your job.

If you are breastfeeding, many babies take more from the breast in the evening, overnight and on weekends, a pattern sometimes called reverse cycling. It helps keep your supply up. Ask your carer to avoid giving a large bottle in the hour before you collect your baby, so they are keen to feed when you arrive.

If your supply dips after returning to work, extra pumping sessions, feeding more often when you are together and drinking enough fluids can help. If it keeps falling, a lactation consultant, public health nurse or health visitor can look at your routine with you.

If you are moving from breastfeeding to formula for some or all feeds, doing it gradually over a week or two is easier on your breasts and your baby. Drop one feed every few days.

Call your care provider if you notice a hard, red, painful area on your breast with fever or flu-like symptoms, as this can be mastitis. Try this: Agree with your carer on what to do if your baby refuses a bottle or finishes the milk early, and write it on your baby's info sheet.

Day 118 · 16 weeks 5 days old

Who is that in the mirror?

Babies are fascinated by faces, and around now a mirror becomes one of the best toys in the house. Your baby will not yet understand that the face they see is their own; that usually comes in the second year. What they see is a cheerful baby who moves when they move and smiles when they smile. Mirror play is good for more than entertainment. It encourages your baby to focus, track movement and notice cause and effect. Placed in front of your baby during tummy time, a mirror gives them a strong reason to lift their head and push up for longer.

Use a shatterproof baby mirror, propped up securely or attached to a play mat, or sit together in front of a large mirror at home. Point to your baby's reflection and name what you see: "There is your nose. There are your hands." Make faces, wave and watch how your baby responds. Some babies coo and chat to their reflection; others stare quietly for long stretches. As with any play, follow your baby's lead and stop when they look away or start to fuss.

Try this: Place an unbreakable mirror in front of your baby at their next tummy time and see whether they stay up a little longer.

Day 119 · 16 weeks 6 days old

Getting ready for the 4-month check

In many places, babies have a checkup at around 4 months, often with a second round of vaccines. The check itself and what is usually given are covered next week. Today is a good day to prepare.

Gather your baby's health record or vaccine card, and check the date and time of the appointment. If your baby is in childcare, arrange the day so you are not rushing back afterwards, as some babies are sleepy or fussy after vaccines.

Make a list of questions. You might want to ask about sleep, feeding amounts, a cough that has hung around, a rash, when to think about solids or anything about development that has been on your mind. If your baby was born early, ask how they are doing for their corrected age. Writing questions down means you will not forget them in the moment.

Think about how you are doing too. Many baby checkups include questions about the parent's mood and sleep. Be honest. This is a chance to get support, not a test.

Try this: Start a note on your phone today called "questions for the 4-month check" and add to it whenever something comes to mind this week.