Week 18
Your baby is about 13 cm (5 in) from crown to rump and weighs roughly 140 g (5 oz), around the size of a bell pepper. Babies vary, and small differences now are normal. The tiny bones of the middle ear are hardening, and the parts of the brain that handle hearing are developing, so sound is starting to reach your baby. Your own appetite may be growing, and night-time leg cramps can begin. The big event on the horizon is the anatomy scan, which many people have between now and 22 weeks. This week explains what it checks, helps you decide about learning the sex, and looks at staying active as your bump grows.
Day 120 · 17 weeks 0 days
Your baby is beginning to hear
The ear has been forming since the early weeks, and now the pieces are coming together. The three tiny bones of the middle ear, the smallest bones in the body, are hardening. The inner ear, shaped like a snail shell, is taking its final form, and the nerves that link it to the brain are growing. Around this time, your baby may begin to pick up sounds. At first these are mostly low, muffled noises from inside your body: your heartbeat, the whoosh of blood through the placenta, your stomach and bowel at work. Your voice travels through your body as well as through the air, so it is one of the clearest sounds in there.
Outside noises are softened by your belly wall and the fluid, a bit like hearing through water. Reliable responses to sound, such as a change in heart rate or a startle, come a little later, usually from about 24 to 26 weeks.
You do not need to do anything special to help your baby's hearing develop. Ordinary life, with its conversations, music and household sounds, is plenty. Very loud, constant noise at work is worth raising with your employer, for your sake as much as your baby's.
Try this: Notice the sounds around you today, and remember that your own voice is the one your baby hears most.
Day 121 · 17 weeks 1 day
Leg cramps often strike at night
You are drifting off when your calf suddenly knots up, hard and painful. Leg cramps are common in the second and third trimesters, and they tend to happen at night. The exact cause is not clear. Tired muscles, changes in circulation and the pressure of your growing uterus may all play a part. When a cramp hits, straighten your leg and gently pull your toes back toward your shin. Standing on a cold floor, walking around, or massaging the muscle can help it let go.
To make cramps less likely, keep moving during the day. Walking and swimming help. Stretch your calves before bed: stand facing a wall, step one foot back and press the heel down until you feel a stretch, then switch sides. Drink enough fluids, and avoid sitting or standing in one position for too long. Do not take supplements for cramps without checking with your care provider first.
Most cramps are harmless. A blood clot in the leg, though rare, can feel similar and is more likely in pregnancy.
Call your care provider if pain in one leg does not go away, or the leg is swollen, red, warm or tender to touch. Get help right away if leg pain comes with chest pain or sudden shortness of breath.
Try this: Do a 30-second calf stretch on each leg before bed tonight.
Day 122 · 17 weeks 2 days
What the anatomy scan looks at
The mid-pregnancy anatomy scan is usually done between about 18 and 22 weeks. It takes around 30 to 45 minutes, sometimes longer if your baby is in an awkward position. A sonographer moves a probe over your belly with gel and takes careful measurements and images.
The scan works through your baby from head to toe. It looks at the shape of the head and the brain, the face and lips, the spine, and the heart with its four chambers and main blood vessels. It checks the stomach, kidneys and bladder, the wall of the belly where the cord joins, and the arms, legs, hands and feet. It also measures growth, and looks at the placenta, the amount of amniotic fluid, and sometimes the cervix.
The sonographer may be quiet while concentrating. That is normal and does not mean something is wrong. In some places they can tell you results straight away. In others, a doctor reviews the images first.
Most scans are reassuring. It is worth knowing, though, that ultrasound cannot find every condition, and some things only show up later or after birth. You will read about what happens if something needs a closer look next week.
Try this: Write down two or three questions to ask at your scan, and bring them with you.
Day 123 · 17 weeks 3 days
To know or not to know the sex
At the anatomy scan, the sonographer can often see whether your baby has a penis or a vulva. If you had a cell-free DNA blood test earlier, you may already have the option to learn the sex chromosomes from that result. Whether you want to find out is entirely up to you.
Some people love knowing. It helps them feel connected, picture the baby and plan. Others want the surprise at birth, or feel the sex matters less than meeting the person. Partners do not always agree, and that is worth talking through before the scan, not in the room.
If you want to know, say so at the start. Ultrasound is very accurate at this stage but not perfect, especially if your baby is curled up or the view is blocked, so hold off on anything permanent. If you do not want to know, tell the sonographer at the start too, and ask them to warn you before showing any revealing views. Ask that it not be written on any notes you take home, or ask for it in a sealed envelope if you want to choose later. Some people feel a twinge of disappointment at the news. That feeling is common, usually passes, and says nothing about how much you will love your child.
Try this: Talk with your partner or support person about whether you each want to know, and agree on a plan before the scan.
Day 124 · 17 weeks 4 days
Keep moving as your shape changes
Staying active through the middle months has real benefits. It can ease back pain and constipation, help you sleep, lift your mood, and support healthy weight gain. The general aim is about 150 minutes of moderate activity spread across the week, such as 30 minutes on five days. If you were less active before pregnancy, start small and build up.
Moderate means you can still talk but not sing. Walking, swimming, water aerobics, stationary cycling and prenatal yoga or Pilates are good choices. Strength training with lighter weights is fine for most people. As your bump grows, a few adjustments help. Your balance shifts, so avoid activities with a high risk of falling, such as skiing or horse riding, and skip contact sports. Avoid scuba diving altogether. As you read in week 17, lying flat on your back can make you light-headed, so do floor exercises on your side or propped up. Drink water, and avoid exercising in great heat. Call your care provider if, during or after exercise, you have vaginal bleeding, fluid leaking, regular painful tightenings, chest pain, dizziness that does not settle, a severe headache, or calf pain or swelling. If you have a medical condition or a pregnancy complication, ask your care provider which activities suit you.
Try this: Plan three 30-minute walks into your calendar this week.
Day 125 · 17 weeks 5 days
Snacks that pull their weight
Around now, many people notice their appetite picking up. As you read in week 12, the extra energy you need in the second trimester is modest: about one healthy snack a day, not a second dinner. So the question is what that snack should be.
Make it bring more than calories. Protein and fibre keep you full longer, and iron and calcium are in high demand now. Good pairings include whole grain toast with peanut butter, yogurt with fruit and nuts, hummus with cut vegetables, a boiled egg with an apple, or cheese with whole grain crackers.
Snacks can also solve problems. Something small every few hours keeps your energy steady, eases heartburn by keeping meals smaller, and helps if you feel woozy between meals. Hunger can arrive suddenly now, so keep a few non-perishable options in your bag or at work.
If you are carrying twins or more, started pregnancy underweight, or have a condition that affects what you eat, your needs may be different. A registered dietitian can help.
Your appetite may also swing from day to day. That is normal. Over a week, your body is usually good at telling you what it needs.
Try this: Prepare one grab-and-go snack today so it is ready when hunger hits.
Day 126 · 17 weeks 6 days
Going to the scan together
The anatomy scan is often the first time you see your baby looking like a baby on screen: a profile, a hand, a foot, a beating heart. For many people it is an emotional moment. For some, it also brings nerves, because the scan is looking for problems as well as checking growth.
It helps to plan the day. Leave enough time to get there without rushing. Wear clothes that let you uncover your belly easily. Eat beforehand, since a long scan on an empty stomach can make you feel faint. Check whether you need a full bladder.
Think about who you want with you. Having someone there can be a comfort if the scan is long or if you hear something unexpected. Some clinics limit visitors, so check ahead.
Afterward, give yourselves a little time. Go for a walk or have a meal together. If the scan was reassuring, enjoy it. If there are questions or follow-up tests, you will have someone to talk it through with. For your partner: On scan day, take care of the logistics: the route, the parking, the time off. Then focus on being present, and if the news is uncertain, stay close and listen.