Week 20

Days 134 to 140 · 19 weeks 0 days to 19 weeks 6 days old · about 4 months This week many babies measure about 64 cm (25.2 in) and weigh about 6.9 kg (15.3 lb). Babies vary widely, so the real measure is whether your baby keeps to their own curve on the growth chart. Your baby is grabbing more accurately and exploring everything with their mouth, which makes small objects a new concern. Many babies also discover their feet around now, a source of endless fascination. For you, the newness of the early weeks has faded, and comparisons with other babies, or feelings you did not expect at this stage, may creep in. This week covers choking hazards, vitamin D, comparing babies, getting out and meeting people, mood later in the first year, and when to expect the first tooth.

Day 134 · 19 weeks 0 days old

Everything goes in the mouth, so check what is within reach

Now that your baby can reach and grab with purpose, anything within range will be picked up and taken straight to the mouth. That is how babies explore, and it means small objects have become a real choking risk. A simple guide: if something fits through the tube of a toilet paper roll, about 4 cm (1.5 in) across, it is small enough to choke a baby. Coins, buttons, beads, pen lids, bottle caps, jewellery and the small parts of older children's toys are common culprits. Uninflated or popped balloons are especially dangerous.

Two items deserve special mention. Button batteries, the flat round ones in remotes, scales, car keys and musical cards, can burn through a baby's esophagus within hours if swallowed. Small, strong magnets can do serious damage inside the gut if more than one is swallowed.

You do not need to babyproof the whole home yet; that comes in week 28, when your baby starts to move. For now, get down on the floor where your baby plays and look around at their eye level.

Get help right away if your baby is choking and cannot cry, cough or breathe, call your local emergency number, or if you think they have swallowed a button battery or magnet, even if they seem fine.

Try this: Sweep the floor and low surfaces where your baby plays today, and put a small box by the door for every tiny object you find.

Day 135 · 19 weeks 1 day old

A quick check on vitamin D

Vitamin D helps your baby build strong bones and teeth. Babies get very little from sunlight, especially since young babies should be kept out of direct sun, and breast milk, though ideal in almost every other way, contains only small amounts of it.

That is why breastfed babies, whether fully or partly breastfed, are advised to have a daily vitamin D supplement of 400 IU (10 micrograms) from birth. In many places this continues until at least the first birthday, and sometimes beyond, depending on local guidance and your baby's diet. Babies with darker skin, and those who live far from the equator, are at higher risk of low vitamin D, so the daily drops matter for them too.

Infant formula already has vitamin D added. A baby who drinks most of their milk as formula may not need extra, but if your baby is combination fed, ask your baby's doctor, nurse or pharmacist whether to keep giving drops. Four months in, it is easy for a daily habit to slip. Drops can be given on the nipple just before a feed, on a clean finger, or with a small syringe or dropper, following the instructions on the product.

Try this: Pair your baby's vitamin D drops with something you do every single day, such as the first feed after waking, and keep the bottle where you will see it.

Day 136 · 19 weeks 2 days old

The trouble with comparing babies

At a baby group, in a family chat or online, it can seem as if every other baby is rolling, sleeping through or laughing more than yours. Comparing is almost impossible to avoid. It can also chip away at your confidence. Remember how wide the normal ranges are. Rolling can come anywhere from about 3 to 7 months. Some babies coo constantly while others watch quietly and take it all in. A baby who focuses on movement may be slower to babble for a while, and the reverse. Babies born early follow their corrected age, so a baby born a month early may simply be a month behind a friend's baby on paper.

What you see from other parents is also edited. Posts show the good nap, not the three hours of crying before it. People often share their baby's latest skill but rarely their own worries.

The comparison that actually matters is your baby against their own past self. Are they doing more than a month ago? Are they growing along their curve, feeding, interested in faces and sounds? If yes, they are on their own good path. If something does worry you, raise it with your baby's doctor or nurse rather than carrying it alone.

Try this: Write down three new things your baby has started doing since they were 3 months old, and read the list when comparisons start to bite.

Day 137 · 19 weeks 3 days old

Your baby has found their feet

Lying on their back, your baby lifts both legs, spots a foot, and grabs it. Soon the toes are in the mouth. This often happens between about 4 and 6 months, and it is a small milestone with a lot behind it.

To reach their feet, your baby needs strong tummy muscles to lift the legs, the flexibility to bring them up, and the coordination to aim their hands at a moving target. It is also part of building a map of their own body. They are learning that these wriggling things belong to them, can be felt from both sides, and move when they decide to move them.

Foot play strengthens the core muscles that will help with rolling and, later, sitting. You may notice your baby rocking from side to side while holding their feet, which can tip them over into a roll.

Bare feet are best for this, so when your home is warm enough, let your baby play without socks during floor time. Brightly patterned socks or soft rattles on the ankles can also draw their attention to their feet.

Try this: At the next diaper change, gently bring your baby's feet towards their hands and name them as they touch: "Here are your toes."

Day 138 · 19 weeks 4 days old

When hard feelings show up later

Many people think of postpartum depression and anxiety as something that starts in the first weeks. As you read in week 4, it can begin then, but it can also appear months later, at any point in the first year. Returning to work, weaning, ongoing lack of sleep, money stress or a difficult relationship can all play a part, and sometimes there is no clear trigger at all. Later-onset depression is easy to miss, because by now you may expect to have "settled in". You might feel irritable or flat rather than sad, snap at the people you love, feel little pleasure in things, or carry constant worry, a racing mind or intrusive, frightening thoughts. Some people feel numb towards their baby and are ashamed to say so.

None of this means you are a bad parent, and it is not something you should simply push through. Talking therapies, peer support and, when needed, medicines that can be used while breastfeeding all help. Partners can be affected too.

Call your care provider if you have felt low, anxious or unlike yourself for two weeks or more, or if daily life feels hard to manage. Get help right away if you have thoughts of harming yourself or your baby: call your local emergency number or a crisis line.

Try this: Ask yourself honestly, "How have I felt most days this past fortnight?", and if the answer worries you, book an appointment today.

Day 139 · 19 weeks 5 days old

Getting out and meeting other people

Four-month-olds are often more fun to take out than newborns. They stay awake longer, take an interest in new faces and settings, and may nap on the move. It is a good time to widen your world a little.

Many communities offer free or low-cost activities for parents and babies: library story times, baby song or rhyme groups, parent drop-ins at community centres, breastfeeding support groups, stroller walking groups and baby swimming or music classes. Your public health nurse or health visitor, local library or community notice board are good places to ask. These outings are not really about your baby learning something. At this age, babies learn just as well at home. They are about you: adult conversation, a reason to get dressed, and people who understand exactly what your days are like. Friendships made now often last for years.

If groups feel daunting, start small. Arrange a walk with one other parent, or go to a group with a friend. It is fine to leave early if your baby needs a feed or a nap. Everyone there has done the same.

Try this: Look up one parent and baby activity near you this week and put it in your calendar, even if you only stay for twenty minutes.

Day 140 · 19 weeks 6 days old

When to expect the first tooth

The first tooth usually appears at around 6 months, but the normal range is wide. Some babies cut a tooth at 4 months, a few are born with one, and others have a gummy smile until after their first birthday. All of this is normal, and the timing often runs in families.

The two lower front teeth, the bottom central incisors, usually come first. The four upper front teeth tend to follow over the next few months. By the first birthday many babies have somewhere between a few and eight teeth, and the full set of 20 baby teeth is usually in by around 2 and a half to 3 years.

You may be able to feel a tooth before you see it, as a small hard ridge under the gum, or see a pale bump or a slightly swollen, reddish patch. Teeth can take days or weeks to break through.

Do not worry if friends' babies are teething and yours is not. Late teeth are rarely a sign of a problem. If your baby has no teeth at all by about 18 months, mention it to your baby's doctor or a dentist.

Try this: With a clean finger, gently run along your baby's lower gums and feel for any small ridges or bumps that might be the first tooth on its way.