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18 Weeks Pregnant: Your Baby May Begin to Hear

Medically reviewed by

Verena Brehm, Midwife Jul 29, 2026

Line illustration of a bell pepper: at 18 weeks pregnant your baby is about the size of a bell pepper, roughly 14cm crown to rump

Line drawing of an 18-week foetus with the ears standing out from the head and long slim limbs

Line drawing of a woman's torso at 18 weeks pregnant, showing the uterus risen to just below the navel with a clear bump

Your baby is the size of a

Bell pepper

~200 grams

~14 cm / ~5.5 in

Key Takeaways

At 18 weeks pregnant, your baby is about 14cm (140mm) from crown to rump and weighs about 200g, per Mayo Clinic. The ears start to stand out, the baby might begin to hear sounds, and the digestive system has started working.

This is when the detailed anatomy ultrasound window opens. The SOGC says this scan is 'usually offered in the second trimester, between 18 and 22 weeks of gestation' and 'looks at your baby's anatomy.'

Movements may be becoming more noticeable, but not for everyone yet. SOGC notes that those in a first pregnancy 'may not feel movement until 18-20 weeks,' and that 'by 24 weeks, almost all women will feel their baby's movements in a predictable way.'

Your Baby at 18 Weeks: Development & Growth

At 18 weeks pregnant, your baby is about 140 millimetres (roughly 14cm) long from crown to rump and weighs about 200 grams, according to Mayo Clinic. This week the ears start to stand out on the head, the baby might begin to hear sounds, and the digestive system has started working.

Your baby measures about 14cm this week — roughly the length of a bell pepper, and noticeably bigger than a few weeks ago. Mayo Clinic gives it as "about 5 1/2 inches (140 millimeters) long from crown to rump" and a weight of "7 ounces (200 grams)." Length is still measured crown to rump, because the legs stay curled at this stage.

The headline change this week is hearing. Mayo Clinic explains that at 18 weeks "your baby's ears start to stand out on the head" and "your baby also might begin to hear sounds." The structures that will one day catch your voice are taking shape.

The gut is coming online, too. Mayo Clinic notes that by this week "the digestive system has started working" — quiet practice for the job it will do in earnest after birth. Small systems, switching on one by one.

Just before now, your baby was busy in other ways. Mayo Clinic notes that around week 17 "your baby is becoming more active, rolling and flipping," and that toenails start developing. All of that motion is happening whether or not you can feel it yet.

Your Body at 18 Weeks: Symptoms & Changes

At 18 weeks pregnant, many mothers are in the steadier stretch of the second trimester, though the common discomforts of pregnancy can still come and go. SOGC lists tender breasts, constipation, backaches, headaches, mood swings and leg cramps among them. This is also the week the anatomy ultrasound window opens, and when some mothers notice the first movements. Every pregnancy is different.

The big event this week is often the anatomy scan. SOGC's routine ultrasound guidance describes this as the ultrasound "usually offered in the second trimester, between 18 and 22 weeks of gestation," adding that "as the name suggests, this type of ultrasound looks at your baby's anatomy." It is a thorough, reassuring look.

What does it check? SOGC explains that images "will be captured to view the development of your baby's brain, face, heart, spine, chest, major organs, feet, and hands," along with the placenta and the fluid around the baby. If your baby's sex is visible and you want to know, SOGC notes "you have the right to request this information."

Movement is the other theme of week 18 — and it is deeply individual. SOGC notes that some women feel movement "as early as 13-16 weeks," while those in a first pregnancy "may not feel movement until 18-20 weeks." If you have felt nothing definite yet, that is squarely normal.

Symptoms haven't necessarily disappeared. SOGC lists tender or swollen breasts, constipation, gas and bloating, backaches, headaches, mood swings and leg cramps among the common discomforts of pregnancy. Any of these can still be part of your week.

Your shape is shifting to carry all of this. SOGC explains that weight gain "isn't just the baby" — "your placenta, increased blood volume, larger breasts, and fat stores to support breastfeeding, also contribute." A rounding middle is your body doing exactly what it should.

What to Do at 18 Weeks Pregnant

NUTRITION AT 18 WEEKS PREGNANT

Keep the second-trimester increase modest. SOGC states: "In the second trimester you need about 340 extra calories per day," noting this "generally equates to 2 or 3 additional servings from any of Canada’s Food Guide’s food groups" — for example a piece of toast and a cup of milk. Quality matters more than quantity.
Stay on top of iron. SOGC advises increasing "your daily iron intake to 27mg daily during the final six+ months of pregnancy to support an increase in red blood cells and fetal tissues" — and notes that, "like most women, you may need a good supplement to meet this need."
Mind your choline. SOGC notes that "choline intake above 450mg a day is linked to improved fetal stress responses and a reduced risk of neural tube defects," and adds that "this vitamin may not be found in your prenatal daily vitamin" — so it is worth checking your label.
Include folate-rich foods and foods fortified with folic acid. Note that folate-rich foods don’t replace supplements. The Public Health Agency of Canada lists corn, oranges, beans, lentils and dark green vegetables like peas, spinach, broccoli and brussels sprouts as sources of folate — while stressing that "dietary sources on their own are not enough" to protect against neural tube defects.

WHAT SUPPLEMENTS TO TAKE AT 18 WEEKS PREGNANT

Keep taking 400mcg of folic acid daily. The Public Health Agency of Canada states that "a daily multivitamin with 400 mcg (0.4 mg) of folic acid is recommended for anyone who could become pregnant," and advises: "Continue taking folic acid throughout your pregnancy and while breastfeeding."
Don’t raise your folic acid dose on your own. The Public Health Agency of Canada advises: "You should not increase your dose of folic acid beyond 1 mg per day without talking to your health care provider."
Use a prenatal that covers iron. SOGC notes that, like most women, "you may need a good supplement" to reach 27mg of iron a day — the second and third trimesters are when this matters most.

LIFESTYLE TIPS AT 18 WEEKS PREGNANT

Keep moving — aim for at least 150 minutes a week. SOGC advises that "pregnant women should accumulate at least 150 minutes of moderate intensity physical activity each week," spread across "at least 3 days a week, and up to 7 days a week." Walking, swimming and stationary cycling are all good options, but reduce your activity if you’re experiencing physical discomfort.
Build in pelvic floor exercises. SOGC notes that "pelvic floor muscle training (e.g., Kegel exercises) can be performed every day to reduce the risk of urinary incontinence." Easy to fold into a daily routine.
Keep caffeine to 300mg a day. Health Canada recommends a maximum daily caffeine intake of 300 mg for people who are pregnant. Health Canada puts one 8oz (237ml) cup of brewed coffee at about 135mg — so roughly two cups is the ceiling, and that total includes tea, cola and chocolate.
Start noticing your baby’s pattern. SOGC notes that "your perception of your baby’s movements is one of the strongest indicators of your baby’s wellbeing." You may not feel a clear pattern yet at 18 weeks, but this is a good time to start paying attention. Now is also a lovely moment to talk to the baby, sing, or play music, as they are starting to hear.

When to Contact Your Doctor or Midwife

Most of week 18 is milestones, not alarms. But some symptoms should always be checked. Contact your doctor, midwife or other health care provider if you experience:

Any vaginal bleeding. SOGC advises: "It's important for you to take any vaginal bleeding seriously. Contact your health care provider as soon as you notice any bleeding." It notes that about one-third of pregnancies have some bleeding before the 20th week, and about half of these continue without further issues — but it should always be assessed.
Signs of infection, or heavy bleeding. SOGC advises that if you have "signs of infection like fever or heavy bleeding, you should see your care provider right away." If bleeding is heavy or you feel very unwell, seek emergency medical care immediately.
Any concern about your baby's movements. SOGC advises that "if you ever have concerns regarding your baby's movement pattern, you should have the baby assessed as soon as possible," and that mothers "should always trust their intuition." Not feeling regular movement yet at 18 weeks is normal — but a change from your baby's usual pattern, once you have one, is worth acting on.
Persistent low mood or disruptive mood swings. SOGC advises that "depression or disruptive mood swings are not normal and it is important to seek help for these more serious concerns."
Severe abdominal pain, a severe or persistent headache, or any symptom that frightens you. Sudden, severe pain warrants urgent assessment — seek emergency medical care immediately if it is intense or you feel faint. For anything that simply worries you, your health care provider is there for exactly that.

Frequently Asked Questions

How big is my baby at 18 weeks pregnant?

At 18 weeks pregnant, your baby is about 140 millimetres — roughly 14cm — from crown to rump and weighs about 200 grams, according to Mayo Clinic. Mayo Clinic describes it as "about 5 1/2 inches (140 millimeters) long from crown to rump" weighing "7 ounces (200 grams)." Length is measured crown to rump at this stage because the legs are still curled.

Can my baby hear me at 18 weeks pregnant?

Hearing is just starting. Mayo Clinic notes that at 18 weeks "your baby’s ears start to stand out on the head" and "your baby also might begin to hear sounds." It is the beginning of the process, not a finished sense — but the structures that will one day catch your voice are forming now.

When is the anatomy scan in Canada?

The Society of Obstetricians and Gynaecologists of Canada (SOGC) describes the anatomy ultrasound as "usually offered in the second trimester, between 18 and 22 weeks of gestation." SOGC recommends that all women have two ultrasounds: a "dating" ultrasound at 11-14 weeks and an "anatomic" ultrasound in this second-trimester window. It "looks at your baby’s anatomy," from the brain and heart to the spine, hands and feet.

Should I feel my baby move at 18 weeks pregnant?

Maybe, maybe not — both are normal. SOGC notes that some women feel movement "as early as 13-16 weeks," while those in a first pregnancy "may not feel movement until 18-20 weeks." By 24 weeks, SOGC says, "almost all women will feel their baby’s movements in a predictable way." If you have concerns about movement, SOGC advises having the baby assessed as soon as possible.

How much caffeine is safe at 18 weeks pregnant?

Health Canada recommends a maximum daily caffeine intake of 300 mg for people who are pregnant. Health Canada puts one 8oz (237ml) cup of brewed coffee at about 135mg, so roughly two cups a day is the ceiling — and that total should include tea, cola and chocolate, which also contain caffeine.

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