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18 Weeks Pregnant your baby, your body and the tests due

Every week brings something new. See how big your baby is, what you might be feeling, and which checks are coming up, all in one calm place.

Your date stays in this browser. It is never sent to us.

A doctor showing a smiling pregnant woman her baby on the ultrasound screen
Week 18They can hear you now

Second trimester

Week 18 They can hear you now

About the size of a bell pepper14.2 cm190 g

  • Your baby

    Your baby can hear sounds, and may startle at a loud noise.

  • You

    Feeling dizzy when you stand up quickly is common, so get up slowly.

  • This week

    Your anatomy scan is due between 18 and 21 weeks.

Your checks

Every check is a chance to see your baby

The usual pattern of care, week by week. Bring your questions to each one; nothing is too small to ask.

  1. Checks the pregnancy is in the womb and finds the heartbeat. After IVF your clinic usually books it.

  2. Your history, blood pressure, a urine test, and blood tests for your blood group, iron and infections.

  3. Confirms your due date and, with a blood test, screens for conditions such as Down syndrome.

  4. Your screening results, your blood pressure and a urine test.

  5. A detailed look at your baby's head, spine, heart, kidneys and limbs, and where the placenta lies.

  6. Checks for diabetes in pregnancy, especially if you are at higher risk.

  7. Iron is checked again, and anti-D is given if your blood group is rhesus negative.

  8. Your bump is measured, and some clinics scan to check growth and the placenta.

  9. Head down or bottom first, and your plans for the birth.

  10. A membrane sweep may be offered, and induction is discussed.

Weeks 18 to 21

Anatomy scan

A detailed look at your baby's head, spine, heart, kidneys and limbs, and where the placenta lies.

Trust your instincts

If something feels wrong, call your doctor straight away

You know your body best. Do not wait for your next appointment, and in an emergency call your local emergency number.

  • 01

    Bleeding

    Any bleeding from the vagina, especially if it is heavy or comes with pain.

  • 02

    Tummy pain

    Severe or constant pain in your tummy, or pain that does not go away when you rest.

  • 03

    Headache and swelling

    A severe headache, blurred vision, or sudden swelling of your face, hands or feet.

  • 04

    Fluid leaking

    A trickle or gush of fluid from the vagina before 37 weeks.

  • 05

    Fewer movements

    Your baby moving less than usual, or a change in their pattern, from about 24 weeks.

  • 06

    Fever or vomiting

    A high temperature, or being sick so often you cannot keep fluids down.

A pregnant woman smiling as she makes a fresh salad at home
6small habits that look after you both

Every day

Small things that make a big difference

  • Folic acid to week 13

    Folic acid and vitamin D

    Folic acid, 400 micrograms a day, and vitamin D. Your doctor may advise a higher dose.

  • All pregnancy

    Food to leave out

    Unpasteurised milk and cheese, raw or undercooked meat, fish and eggs, and fish high in mercury.

  • All pregnancy

    No alcohol, no smoking

    No amount of alcohol is known to be safe in pregnancy, and help to stop smoking is free in many countries.

  • 150 minutes a week

    Keep moving

    Walking, swimming or pregnancy yoga, if your doctor is happy that you do. Keep caffeine under 200 mg a day.

  • From 28 weeks

    Sleep on your side

    Going to sleep on your side, not your back, is safer for your baby in the last months.

  • Ask your doctor

    Your vaccines

    Whooping cough and flu vaccines protect you, and your baby in their first weeks. Ask when they are due where you live.

An expecting couple smiling and holding up their baby's scan picture

However this week feels, you are not doing it alone.

Pregnant after fertility treatment, or simply full of questions? Talk to a specialist about your scans, your tests and the care you need next.

Questions

The questions every parent asks

01How are the weeks of pregnancy counted?

From the first day of your last period, not from conception. So at 4 weeks pregnant you conceived about two weeks ago, and a pregnancy lasts about 40 weeks, or 280 days.

02When does each trimester start?

The first trimester runs to the end of week 13, the second from week 14 to the end of week 27, and the third from week 28 until your baby is born.

03How accurate is my due date?

It is an estimate. Only about one baby in twenty is born on the due date itself; most arrive between 37 and 42 weeks. Your dating scan at 11 to 14 weeks gives the most reliable date.

04What if my baby is smaller or bigger than these sizes?

The sizes here are averages, and healthy babies vary. Your doctor follows your own baby's growth at your checks and scans, and will tell you if anything needs a closer look.

05When will I feel my baby move?

Usually between 16 and 24 weeks, often later in a first pregnancy. Once you feel a regular pattern, call your maternity unit the same day if the movements slow down or change.

06How do I count my weeks after IVF?

Use the due date from your clinic. It is set from your transfer date and the age of the embryo, and counts weeks the same way as a natural pregnancy, so the tracker works just the same.

07When should I start antenatal care?

As soon as you know you are pregnant. Your first appointment is usually between 8 and 10 weeks, and an early scan may come sooner after fertility treatment.

08Does the tracker keep my date?

Only in your own browser, on this device, so the tracker opens on your week next time. It is never sent to us. Reset forgets it.

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