you're 18 weeks pregnant.
last revised · baby is about 14.2 cm (5.6") · 190 g (6.7 oz)
At 18 weeks pregnant, your baby is about 14.2 cm and 190 g — The baby is twisting, stretching, and yawning.
about the size of a…
The baby is twisting, stretching, and yawning. The reproductive system is fully formed and detectable on ultrasound.
this week's highlights
- Yawning and stretching
- Reproductive system formed
- Myelin coats nerves
- Ear bones harden
how your baby looks
Limbs are graceful and elongated. Skin is still wrinkly because there's no fat yet, but eyebrows and head hair are filling in.
body in focus
- head
- Ear bones harden — hearing is improving fast.
- body
- Myelin sheaths begin coating nerves to speed signals.
- hands
- Tiny hands can grip and pat at the umbilical cord.
- feet
- Kicks are stronger and increasingly noticeable.
what's happening in your body
Many feel quickening now — distinct little flutters or kicks. Round-ligament twinges and lower-back ache are common as the bump grows.
symptoms at 18 weeks
- Distinct movements
- Flutters are graduating into recognisable pokes and rolls for many people this week. Movements are still irregular — a quiet day at this stage is not yet something to track.
- Dizziness when lying flat
- The uterus is now heavy enough that lying on your back can compress a major vein and make you light-headed. Roll onto your side and it passes within moments — and take it as your cue to favour side-lying.
- Lower back ache
- The bump's forward pull is now real, and back ache becomes one of the most common mid-pregnancy complaints. Heat, posture work and pregnancy-safe massage all earn their keep.
- Leg cramps at night
- Sharp calf cramps that wake you are common from mid-pregnancy. Stretch the calf hard (toes toward your shin) to break the cramp, and stretch before bed to prevent it.
- Increased vaginal discharge
- Discharge keeps increasing as pregnancy progresses — thin and milky is normal. Any bleeding, or fluid that seems watery and continuous, needs a same-day call to your midwife.
- Faster-growing bump
- The uterus now reaches roughly halfway to your navel and growth becomes visible week to week. Strangers may begin to notice — with all the commentary that entails.
gentle tips
- Note the first kick you feel — a memorable moment.
- Drink water before standing up — dizziness is common.
- Get your blood pressure checked at your next visit.
- Pelvic-floor exercises help support the growing uterus.
- Discuss any unusual swelling or headaches with your provider.
your week 18 checklist
- Attend the anomaly scan if scheduled this week — allow plenty of time, it is a long appointment
- Formally notify your employer in writing if required for maternity leave (deadlines are typically around week 25)
- Book antenatal classes now if you have not — the 30-to-36-week courses fill up
- Start a kick-awareness habit: notice when the baby tends to be active, without formal counting yet
what to expect next
The anatomy scan is usually scheduled now or just after. You may also start feeling stronger kicks each day.
common questions at week 18
How big is the baby at 18 weeks?
At 18 weeks, the baby measures about 14.2 cm and weighs approximately 190 g (14.2 cm (5.6") · 190 g (6.7 oz)).
What is developing at 18 weeks?
Limbs are graceful and elongated. Ear bones harden — hearing is improving fast. Key milestones this week include: Yawning and stretching; Reproductive system formed; Myelin coats nerves; Ear bones harden.
What symptoms are common at 18 weeks pregnant?
Many feel quickening now — distinct little flutters or kicks. Round-ligament twinges and lower-back ache are common as the bump grows.
What should I do at 18 weeks pregnant?
The anatomy scan is usually scheduled now or just after. Note the first kick you feel — a memorable moment. Drink water before standing up — dizziness is common. Get your blood pressure checked at your next visit.
What does the 20-week anomaly scan look for?
The sonographer examines the baby's anatomy in detail — brain, face, spine, heart, stomach, kidneys, bladder, arms, legs, hands and feet — plus the placenta's position and the amniotic fluid level. It screens for 11 specific conditions, including spina bifida and serious heart defects. Most scans are entirely reassuring, and it is usually when you can find out the sex if you wish.
Should I be feeling kicks every day at 18 weeks?
Not yet — at 18 weeks movements are still inconsistent, and gaps of a day or more are common and normal. The baby is small enough to move without you feeling it, especially with an anterior placenta. A regular daily pattern typically establishes between 24 and 28 weeks, which is when movement awareness starts to matter clinically.
What is a low-lying placenta and should I worry?
At the anomaly scan, some placentas are found sitting low in the uterus, near or over the cervix. In the large majority of cases, the placenta effectively moves up as the uterus grows, and a follow-up scan around 32 weeks confirms it has cleared. Only if it remains over the cervix (placenta praevia) does it change birth planning — your team will explain exactly what it means for you.
helpful tools
- Belly Timeline
Document your bump week by week with photos.
- Kick Counter
Track fetal movement — kicks usually begin around week 18–22.
- Milestones
Week-by-week milestones tied to your due date.
Medically aligned with guidance from WHO, NHS and ACOG. How we write.