Week 18 Pregnancy

Second Trimester

Last reviewed: July 2026

18 weeks pregnant at a glance

You are in the second trimester.
Your baby is roughly the size of a bell pepper.
The anomaly scan is usually booked for between 18 and 21 weeks.
Every pregnancy is different, so don't worry if your experience varies slightly.

You are 18 weeks pregnant and in your second trimester. Your baby is about the size of a bell pepper. This week's key development: Halfway Almost There. NHS note: The anomaly scan is usually booked for between 18 and 21 weeks.

The Anomaly Scan Window

Between 18 and 21 weeks, you'll be offered the anomaly scan. It looks closely at your baby's bones, heart, brain, spinal cord, face, kidneys and abdomen.

This page is for general pregnancy planning and date guidance only. It is not medical advice, diagnosis, or treatment. Pregnancy dates are estimates and can change after a scan or advice from your midwife, GP, or maternity team. Always speak to a qualified healthcare professional if you have symptoms, concerns, or questions about your pregnancy.

Week 17

Week 19

Baby's Development

Your baby is about the size of a bell pepper.

Halfway Almost There — Your baby is yawning, hiccuping, and swallowing amniotic fluid — good practice for feeding after birth. If you're having a girl, her uterus and fallopian tubes are fully formed. If you're having a boy, his genitals are now visible on a scan.

Bell pepper

Approx. 14.2cm

Your Symptoms

Dizziness
Swollen feet
Leg cramps

Every pregnancy is different. You may experience all, some, or none of these symptoms — and that's completely normal. If anything concerns you, speak to your midwife.

NHS Appointments

The anomaly scan is usually booked for between 18 and 21 weeks.

Practical Advice for Week 18

Nutrition

Continue vitamin D daily.
Eat slowly and sit upright after meals to reduce heartburn.
Iron-rich foods remain important — your blood volume is still increasing.
Include protein with every meal — it helps you feel full and supports baby's growth.

Exercise

Keep moving — moderate exercise reduces the risk of gestational diabetes.
Ankle circles and foot exercises can help with swelling.
If dizziness occurs during exercise, stop, sit down, and drink water.
Consider a pregnancy support belt if back pain is becoming troublesome.

Wellbeing

Leg cramps can strike at night — stretching calves before bed helps.
Swollen feet are common — elevate them when resting.
Stand up slowly to avoid dizziness as your blood pressure adjusts.
If you're feeling emotionally flat, talk to someone — your midwife, partner, or a friend.

Preparation

The anomaly scan is usually booked between 18 and 21 weeks.
Write down any questions for your sonographer — they're happy to explain what they see.
Start thinking about what you need for the baby's arrival — keep a running list.
Research local NCT groups or bumps-and-babies groups for social support.

Tip of the Week

When standing up, do it slowly to avoid dizzy spells as your blood pressure adjusts.

Frequently Asked Questions for Week 18

How many months is 18 weeks pregnant?

At 18 weeks pregnant, you are roughly 4 months pregnant. Remember that pregnancy is typically measured in weeks rather than months for clinical accuracy.

What size is the baby at 18 weeks?

At 18 weeks, your baby is roughly the size of a bell pepper (about 14.2cm). Your baby is yawning, hiccuping, and swallowing amniotic fluid

What are the common symptoms at 18 weeks pregnant?

Common symptoms at this stage include dizziness, swollen feet, leg cramps. Remember that every pregnancy is unique, and it's normal to experience different symptoms.

Is 18 weeks in the second trimester?

Yes, 18 weeks falls within the second trimester.

Are there any NHS appointments at 18 weeks?

The anomaly scan is usually booked for between 18 and 21 weeks.